CMS COLLEGE OF SCIENCE AND COMMERCE

(Autonomous) Chinnavedampatti, Coimbatore - 641 049

An Autonomous Institution, Affiliated to Bharathiar University

Approved by AICTE, UGC

A+ Grade by NAAC (3.38 points)

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Website: www.cmscbe.com

SCHOOL OF BIOLOGICAL SCIENCES

HUMAN NUTRITION

STUDY MATERIAL

EXTRA DISCIPLINARY COURSE (EDC)

SBS, EDC Human Nutrition study material 2016-17

CONTENTS

UNIT TOPIC PAGE NO

FOOD – AN INTRODUCTION 3

INTRODUCTION TO FOOD GROUPS 4

WATER AND ITS PROPERTIES 8

I FUNCTIONS OF FOOD 14

FUNCTIONAL FOODS 17

FOOD HABITS CLASSIFICATION 20

SOURCES AND FUNCTIONS OF CARBOHYDRATES 23

II SOURCES AND FUNCTIONS OF FAT 30

SOURCES AND FUNCTIONS OF PROTEINS 41

ENERGY UNITS 44 ENERGY VALUE OF FOODS 45 RELATIONSHIP BETWEEN OXYGEN USED AND CALORIFIC VALUE 47

ENERGY BASAL METABOLISM 49

CALCULATING BASAL METABOLIC RATE 49 III FACTORS AFFECTING BASAL METABOLISM 52 TEMPERATURE REGULATION OF THE HUMAN BODY 52 TOTAL ENERGY REQUIREMENT 53 DAILY ENERGY REQUIREMENTS AND DAILY ENERGY 55 INTAKES BALANCED DIET FORMULATION 55

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MINERAL NUTRITION 59

IV VITAMINS 69 FOOD PIGMENTS AND FLAVORING AGENTS 83 NUTRITION AT VARIOUS STAGES OF GROWTH AND DEVELOPMENT 85

DIET FOR INFANTS V 88 DIET FOR PREGNANT AND LACTATING WOMEN 96 DIET FOR OLDER PERSONS 99

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SBS, EDC Human Nutrition study material 2016-17

FOOD – AN INTRODUCTION

Food has been a basic part of our existence. Life cannot exist without food. After air and water, food is the utmost important thing for survival. There is no other habit, practice or factor that influences the health of an individual, as much as the kind and amount of food consumed. Through, the centuries, food has also been used, as an expression of love, friendship and social acceptance.

Food refers to anything, which nourishes the body. It would include solids, semi-solids, and liquids which can be consumed and which help to sustain body and keep it healthy.

Food is a substance which after ingestion, digestion and absorption is capable being utilized by the body for its various functions

Ingestion means intake of food. It is intake of a substance which should be chewable, palatable and should enter the gastrointestinal tract.

After ingestion, food undergoes a process of digestion. Digestion is a process by which complex substance in food is broken down into simpler substance, which the body can take in and use. Some of this complex substance such as carbohydrates, protein and fats undergo some change during digestion.

The end products of digestion or the nutrients present in the small intestine can be used by the body only when they enter these blood stream. This process of movement of digested food or nutrients from the small intestinal wall to the blood stream is termed as absorption of food.

Food supplies nutrients to the body, which help us to maintain our nutritional status and health. For example, apple can be classified, as food, as it is capable, of being ingested, digested and finally supplies nutrients to the body after being absorbed. These materials help the body in carrying out the day today activities and thus maintain health.

The nutrients provided by food are carbohydrates, protein, fats, minerals, vitamins, and water and these performs various functions in the body for maintaining our health. Apart from performing this major function, food has another function also.

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UNIT I

INTRODUCTION TO FOOD GROUPS

The five major food groups are Proteins, Carbohydrates, Vitamins and minerals, Fibre and Fats. They form the major components of our diet. A healthy diet should contain a balanced amount of all these food groups.

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The following pyramid depicts how much of each food group should be in our diet.

Grains:

Whole grains and complex carbohydrates are an important source of energy, and make up the base of the food pyramid. Whole grains are the best for us to eat, which are made from whole-wheat flour, rather than white flour. They are not as processed, and therefore still contain many of their vital nutrients and fiber. It is recommended to eat 6-11 servings from this group each day. Examples include:

 Whole wheat bread  Brown rice  Muesli  Whole wheat pasta

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Fruits and Vegetables:

These nutrient-rich foods are all-natural because they come from the earth, and are loaded with many different nutrients, including fiber, Vitamin A, Vitamin C, iron, potassium, and folic acid. Eating a wide variety of fruits and vegetables helps to garner the greatest health benefits. It is recommended to eat 3-5 vegetable servings and 2-4 fruit servings per day. Some examples of low-fat fruits and vegetables are:

 Celery  Cucumber  Carrots  Peas  Apples  Oranges  Strawberries (high sugar)  Nectarines and peaches

Proteins:

Proteins help our body to build and retain muscle, as well as provide the energy needed each day. Protein-rich foods such as beans, lean meats, poultry, fish, and eggs also provide healthy doses of zinc and iron.

Some of the foods in this group can be high in cholesterol, which has to be kept in mind while making food choices. 2-3 servings of protein are recommended each day. Aside from meat, protein can be found in the following items:

 Nuts  Lentils  Cheese and other dairy products (often high in fat)  Tofu

Dairy:

Dairy products provide us with bone-building calcium, which is known to help prevent osteoporosis. While this is a very important food group to include in a balanced diet, it is important to remember that some dairy foods are high in fat, such as ice cream and cheese. It is recommended to eat 2-3 servings of dairy daily. Calcium can also be got from:

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 Seaweed (in sushi)  Almonds  Beans  Broccoli  Figs

Fats and sweets:

While technically not a food group, this category is here because most people can’t live without at least some of the tempting treats within! The foods in this group, which include butter, candy and desserts, oils, and sugars, provide very little nutritional benefit when consumed. Use these foods in moderation, and stick to healthy fats such as:

 Avocado  Nuts  Oily fish (tuna, salmon)  Olives

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WATER AND ITS PROPERTIES

Water can be safely considered as one of the most vital nutrient for the human body as it is essential for every cell. The human body can last weeks without food, but only days without water. The body is made up of 50 to 75 per cent water. Water forms the basis of blood, digestive juices, urine and perspiration, and is contained in lean muscle, fat and bones.

As the body can’t store water, we need fresh supplies every day to make up for losses from the lungs, skin, urine and faeces (poo). The amount we need depends on our body size, metabolism, the weather, the food we eat and our activity levels.

Water in our bodies

Some facts about our internal water supply include:

 Body water content is higher in men than in women and falls in both with age.  Most mature adults lose about 2.5 to 3 litres of water per day. Water loss may increase in hot weather and with prolonged exercise.  Elderly people lose about two litres per day.  An air traveller can lose approximately 1.5 litres of water during a three-hour flight.  Water loss needs to be replaced.

Importance of water

Water is needed for most body functions, including to:

 maintain the health and integrity of every cell in the body  keep the bloodstream liquid enough to flow through blood vessels  help eliminate the by-products of the body’s metabolism, excess electrolytes (for example, sodium and potassium), and urea, which is a waste product formed through the processing of dietary protein  regulate body temperature through sweating  moisten mucous membranes such as those of the lungs and mouth  lubricate and cushion joints  reduce the risk of cystitis by keeping the bladder clear of bacteria  aid digestion and prevent constipation  moisturise the skin to maintain its texture and appearance  carry nutrients and oxygen to cells

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 serves as a shock absorber inside the eyes, spinal cord and in the amniotic sac surrounding the fetus in pregnancy.

Water content in food

Most foods, even those that look hard and dry, contain water. The body can get approximately 20 per cent of its total water requirements from solid foods alone. The digestion process also produces water as a by-product and can provide around 10 per cent of the body’s water requirements. The rest must come from liquids.

Recommended daily fluid intake

Approximate adequate daily intakes of fluids (including plain water, milk and other drinks) in litres per day include:

 infants 0–6 months – 0.7 (from breastmilk or formula)  infants 7–12 months – 0.9 (from breastmilk, formula and other foods and drinks)  children 1–3 years – 1.0 (about 4 cups)  children 4–8 years – 1.2 (about 5 cups)  girls 9–13 years – 1.4 (about 5-6 cups)  boys 9–13 years – 1.6 (about 6 cups)  girls 14–18 years – 1.6 (about 6 cups)  boys 14–18 years – 1.9 (about 7-8 cups)  women – 2.1 (about 8 cups)  men – 2.6 (about 10 cups).

These adequate intakes include all fluids, but it is preferable that the majority of intake is from plain water (except for infants where fluid intake is met by breastmilk or infant formula). Sedentary

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SBS, EDC Human Nutrition study material 2016-17 people, people in cold environments, or people who eat a lot of high-water content foods (such as fruits and vegetables) may need less water.

Some people need higher fluid intake

People need to increase their fluid intake when they are:

 on a high-protein diet  on a high-fibre diet, as fluids help prevent constipation  pregnant or breastfeeding (the fluid need is 750-1,000 ml a day above basic needs)  vomiting or have diarrhoea  physically active  exposed to warm or hot conditions.

Risks of inadequate fluid intake

Not drinking enough water can increase the risk of kidney stones and, in women, urinary tract infections. It can also lower your physical and mental performance, and salivary gland function, and lead to dehydration.

Dehydration

Dehydration occurs when the water content of the body is too low. This is easily fixed by increasing fluid intake.

Symptoms of dehydration

 thirst  headaches  lethargy  mood changes and slow responses  dry nasal passages  dry or cracked lips  dark-coloured urine  weakness  tiredness  confusion and hallucinations.

If dehydration is not corrected by fluid intake, eventually urination stops, the kidneys fail and the body can’t remove toxic waste products. In extreme cases, dehydration may result in death.

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Causes of dehydration

There are several factors that can cause dehydration including:

 not drinking enough water  increased sweating due to hot weather, humidity, exercise or fever  insufficient signalling mechanisms in the elderly – sometimes, they do not feel thirsty even though they may be dehydrated  increased output of urine due to a hormone deficiency, diabetes, kidney disease or medications  diarrhoea or vomiting  recovering from burns.

Dehydration in the elderly

Elderly people are often at risk of dehydration due to:

 changes to kidney function, which declines with age  hormonal changes  not feeling thirsty (because the mechanisms in the body that trigger thirst do not work as well as we age)  medication (for example, diuretics and laxatives)  chronic illness  limited mobility.

Dehydration in babies and children

Children are susceptible to dehydration, particularly if they are ill. Vomiting, fever and diarrhoea can quickly dehydrate a baby. Dehydration can be a life-threatening condition in children. If you suspect dehydration, take the child immediately to the nearest hospital emergency department.

Some of the symptoms of dehydration in a child include:

 cold skin  lethargy  dry mouth  depressed fontanelle (the soft spot on top of a baby’s skull where the bones are yet to close)  a blue tinge to the skin as the circulation slows.

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Risks of excessive water intake

Drinking too much water can also damage the body and cause hyponatraemia (water intoxication). Hyponatraemia is rare in the general population. Hyponatraemia occurs when sodium in the blood drops to a dangerously low level. Sodium is needed in muscle contraction and for sending nerve impulses.

If large amounts of plain water are consumed in a short period of time, the kidneys cannot excrete enough fluid. Hyponatraemia can lead to headaches, blurred vision, cramps (and eventually convulsions), swelling of the brain, coma and possibly death.

For water to reach toxic levels, you would have to consume many litres in a short period of time. Hyponatraemia is most common in people with particular diseases or mental illnesses (for example, in some cases of schizophrenia), endurance athletes and in infants who are fed infant formula that is too diluted.

Water fluoridation

Tap water in many cities also contains fluoride, which is good for teeth and bones. Bottled water does not usually have good levels of fluoride. Water fluoridation helps prevent dental decay, and is a safe and effective way of allowing everybody access to the benefits of fluoride.

Water and sports performance

Fluid needs of athletes during training and competition vary greatly depending on many factors. For smaller athletes exercising in mild conditions, less fluid may be needed. Well-trained athletes competing at high intensities in warm conditions may prefer more fluid.

Fluid retention

Many people believe that drinking water causes fluid retention. In fact, the opposite is true. Drinking water helps the body rid itself of excess sodium, which results in less fluid retention. The body will retain fluid if there is too little water in the cells. If the body receives enough water on a regular basis, there will be no need for it to conserve water and this will reduce fluid retention.

Sources of fluid

Fluids include fresh water and all other liquids like milk, coffee, tea, soup, juice and even soft drinks. Fresh water is the best drink because it does not contain kilojoules and is best for hydrating

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SBS, EDC Human Nutrition study material 2016-17 the body. Milk (particularly low-fat varieties) is an important fluid, especially for children, and is about 90 per cent water. Tea can be an important source of fluid. Tea can help you meet your daily fluid recommendations, and is a source of antioxidants and polyphenols, which appear to protect against heart disease and cancer.

Fresh fruit is preferable to fruit juice because it has more fibre and nutrients, and less sugar. Avoid sugary and artificially sweetened drinks

The Australian Dietary Guidelines recommend that all Australians limit their intake of drinks containing added sugar, including sugar-sweetened soft drinks and cordials, fruit drinks, vitamin- style waters, flavoured mineral waters, energy and sports drinks.

Consumption of sugary drinks provides additional energy (kilojoules) to the diet, but no other essential nutrients. There is strong evidence of the association between the consumption of sugary dinks and excess weight gain in children and adults, as well as reduced bone strength and tooth decay. Artificially sweetened drinks add very little energy (kilojoules) to the diet and therefore do not contribute directly to weight gain. However, artificially sweetened drinks still maintain the ‘habit’ of drinking sweet drinks, may lead to decreased bone density (as people may drink less milk) and can contribute to tooth decay due to their acidity. Tips for increasing water intake

 Add a squeeze of lemon or lime juice to plain water to add variety.  Keep a bottle or glass of water handy on your desk or in your bag.  Add ice cubes made from fresh fruit to a glass of water.

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FUNCTIONS OF FOOD

The functions of food can be broadly classified into three main categories.

1. Physiological functions of food. 2. Psychological functions of food. 3. Social function of food.

1) Physiological functions of food: The physiological functions of food can be further sub-divided as follow: a. Energy giving. b. Body building. c. Regulatory and protecting functions of food. a) Energy giving: The body needs a constant supply of energy to carry out the involuntary processes of which we are not even aware, like, respiration, circulation of blood etc. which are essential for continuance of life. Energy is also required to carry out voluntary activities like professional, household and recreational activities, which every human being indulges in like, either jumping, walking, playing etc. Besides this, some amount of energy is also required to convert the ingested food into usable nutrients in the body and the heat released during this process helps to keep the body warm. Energy is mainly provided to our body through carbohydrates and fats in the food. Rich sources of carbohydrates are cereals, sugar, jiggery, potatoes, honey etc. Good Sources of fats include ghee, oil, nuts etc. A major part of our daily diet is constituted by these energy-rich food materials. b) Body Building: The foods we eat become a part of us. Thus one of the most important functions of food is that of building the body. A newborn baby weighing 2.7 - 3.2 Kg can grow to its potential adult size of 55 - 70 Kg., if the right kind and amount of food are eaten from birth to adulthood., In adult life, the food eaten each day helps to maintain the structure of the adult body, and to replace worn out cells of the body.

Building of new tissues is very important particularly for the growing children and pregnant women. There is also a continuous breakdown of old tissues and building up of new tissues going on in our body at all ages irrespective of the apparent growth, thus maintaining a need for body building nutrients.

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For the body building purposes, the major nutrients utilized are proteins and minerals. Proteins are mainly provided through milk and milk products, meat, fish, poultry, nuts, soybean, and pulses etc. c) Regulatory and Protective function: The third physiological function of food is to regulate the activities of the body. It includes regulation of such varied activities as beating of the heart, maintenance of body temperature, muscle contraction, control of water balance, clotting of blood, removal of waste products from the body etc. For any of these processes, one or the other nutrients is responsible. For example Vitamins of the B groups are an integral part of the enzymes and are responsible for metabolizing food and thus release energy. Vitamin K is an essential factor in clotting of blood.

Apart from regulating our body processes, food also protects us from various infections, diseases, and injuries. For example, Consumption of Vitamin A and Vitamin C rich food help in building resistance in the body to fight against invading organism.

The main nutrients which perform these functions include proteins, vitamins, minerals, water and roughage. Although these nutrients are required by the body in very small amounts, yet it is very important for them to be present in our daily diets. The major sources of these protective and regulatory nutrients are green leafy vegetable, milk, fresh fruits and vegetable, fish etc.

2) The Psychological Functions of food

The second major function of food is the psychological function. Food must also satisfy certain emotional needs. These include sense of security, love and attention. Everyone grows in a particular culture with its own unique food habits of that culture and caste.

The person begins to associate the food habits and foods commonly consumed by him, as it gives him a sense of security and satiety. The foods daily eaten by us, give us more mental satisfaction, even a nutritional balanced meal may not be satisfying to the individual, if food include is unfamiliar or distasteful to him/her.

In a friendly gathering, one may try unfamiliar foods and thus enlarge our food experiences. During the course of time and repeated experience, strange foods become familiar and new tastes are formed. These new taste are developed should again be satisfying to the mind. For example, a person accustomed to traditional Indian cusine, takes time to adjust to Chinese or western dishes, but feels mentally satisfied at the site of familiar foods.

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3) Social function of Food

Food and eating has significant social meaning. Share food with any other person implies social acceptance. When you share a meal with anyone else, you are expressing your acceptance of friendship and respect for that person. Earlier only persons enjoying equal status in society eat together. A person would never share a meal with someone inferior to him in social terms. Food is also a symbol of our social life. Food is a medium through which we express our happiness. For example, feasts are given at specific states of life, such as birth, mundane ceremony, birthday, marriage etc. Sweets are also distributed and exchanged to mark certain auspicious occasion like festivals. Food is the common link in a meeting, party or get-together that attracts people to come to such social gatherings. Refreshment served even at officials meeting creates a relaxed atmosphere, where people can exchange their views. The menu for such get-to-gather should bring the people together, rather than divide them. Foods help to strengthen mutual friendship.

For example, inviting friends and relatives over meals signify acquaintance and hospitality. Food also has a specific significance and meaning in the religious context. Certain food items such as fruits, sweets, and coconut are offered to the deity in temples. Often sweets are prepared at temples and gurudwaras and distributed to devote as a benediction or prasad.

Further, people of a given religious community share a common eating pattern. This is because religious texts and practices strongly recommend some foods while rejecting others. Food thus becomes an integral part of the social and religious life of people.

Thus it can be concluded that food performs various important functions from satisfying hunger to building mutual understanding and above all helps to maintain our health and adequate nutritional status.

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FUNCTIONAL FOODS

Food supplies the body with all the vital nutrients and energy it requires to keep running, allowing an individual to grow and thrive. Food is an important material in the body, and its consumption is necessary for survival. Food provides the body with energy in the form of calories, fuelling the cells in the same way that gasoline fuels a car. Any excess is stored in the form of fat in adipose cells, a throwback to prehistoric days when food was not so readily available. Food also provides pleasure, and it is commonly associated with social functions and positive emotions.

Food is important for life. To be healthy and active, we should certainly have enough food. But the foods we eat should also be safe and rich in all the nutrients our body needs. We should choose from a wide variety of foods and we should eat them regularly, throughout the day, every day of the year. Do not forget that we should also enjoy the food that we eat; it should look, smell and taste good. Without good nutrition, children and young people cannot develop their potential to the full, and adults will have difficulty in doing their best.

Food provides our bodies with what they need to:

 stay alive, be active, move and work;  build new cells and tissues for growth;  stay healthy and heal themselves;  prevent and fight infections.

Functional foods are similar to conventional foods that form part of a normal diet – the difference is that they have a demonstrated positive benefit to overall health as well as the potential to reduce the risk of chronic diseases.

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Food Function and Structure

We all eat food because it provides the fundamental types of materials required to keep our bodies functioning.

These materials can be categorised as:

 macronutrients – carbohydrates, proteins, fats and oils  micronutrients – vitamins and minerals  dietary fibre – cellulose, pectin and gums  dietary water – keeping the body hydrated  phytochemicals – biologically active compounds from fruits and vegetables.

It has been estimated that an average person consumes 25 tonnes of food within their lifetime, and most of that food sits in the macronutrient category.

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Macronutrients

Macronutrients are required in large amounts to provide the energy needed to maintain body functions and carry out the activities of daily life. There are three macronutrients – carbohydrates, proteins and fats.

Micronutrients

Micronutrients are substances such as vitamins and minerals that are necessary dietary components. Although needed in only small amounts, they are essential for health and wellbeing.

Dietary fibre

Dietary fibre is that portion of the food we eat that is resistant to digestion and absorption in the small intestine. Fibre is found in fruits, vegetables, nuts and grains and is an important ingredient of a healthy diet.

Water

Water is the most abundant and most frequently overlooked component of food. The water content of solid foods makes a considerable contribution to our total water intake.

Phytochemicals

Phytochemicals are biologically active compounds that are found in small amounts in fruits and vegetables. These compounds contribute to human health because they might help protect against degenerative diseases such as cancer.

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FOOD HABITS CLASSIFICATION

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Food habits

We are what we eat as the saying goes. But it may be the other way around. Who we are determines what we eat. More precisely, how we eat. While God has created each individual in his or her unique way, the human behaviour too follows distinct patterns.

To put in other words, the way we do things is part of our personality and that includes our eating habits too. According to sociologists, our lifestyle and eating habits may be pre-determined by our personality.

Here are seven broad classifications of food habits based on the personalities who get habituated to such food menu either by practice or force of circumstance:

1) Accidental diner:

They love to munch. They are often unconscious of their eating habits and do not discriminate between foods on the basis of nutritional quality, freshness, or calorie content. Meals are rarely planned ahead of time and shopping decisions are typically made spontaneously, based on convenience and accessibility. Excessive food consumption and bingeing can occur with feelings of boredom or frustration.

2) Irregular diner:

These people typically pay little attention to their nutritional needs. Eating is considered a mere necessity. Food is consumed like fuel in order to keep functioning. Quality and presentation are of minor importance. By the time they remember to eat, they are ravenous, eat quickly and often overindulge.

3) Habitual diner:

As the name indicates, habitual diners prefer all things in keeping with a certain routine. Many of their habits are acquired during adolescence or young adulthood, such as smoking, drinking or enjoying certain foods. If reminded that their behaviour could become detrimental to their health, they like to point out that it never caused them reason for concern in the past.

4) Social diner:

They easily adapt their habits to the people around them. Eating together is considered as an act of sharing, belonging, friendship or love. Preparing food for others is a way of expressing affection, nurturing and support. For them, dining out is at the core of romance. Gathering for a meal is part of

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SBS, EDC Human Nutrition study material 2016-17 every celebration. Unfortunately, by focusing primarily on others, social diners have a tendency to forget about themselves and neglect to take care of their own needs.

5) Tragic-romantic diner:

It is not uncommon for tragic-romantic diners to develop dysfunctional and sometimes even destructive eating patterns. The spectrum may range from morbid obesity to life-threatening anorexia. Many suffer from addiction to alcohol, nicotine or drugs. Although most of them are keenly aware of their situation, a deep sense of helplessness can keep them from making positive changes.

6) Reformed diner:

People sometimes become reformed diners during or in the aftermath of a health crisis. Coming face to face with their vulnerability, they want their normal lives back as quickly as possible. If that requires radical lifestyle changes, so be it. Once they discover the benefits and positive results become evident, they are hooked.

With the zest of a “born-again” believer, they follow strict diets, rigorous work-out schedules, read every publication on the subject and generously dish out free advice to everyone who is willing to listen.

7) Healthy diner:

In order to become a healthy diner, it is essential to understand the close relationship between one’s eating habits and one’s personality. While “health” is a relative and temporary state, the need to be healthy is not. Regardless of age, physical condition, medical history or genetic make-up, the quest for well-being is universal. This includes far more than the absence of disease or pain.

Whether someone tries to make lifestyle changes to get more energy, lose weight, prolong youth, cope with disabilities or overcome a chronic illness, the goal is always the same: Being well.

Becoming a healthy diner involves more than revision and (if necessary) modification of one’s eating habits. Having the right relationship to food is only one aspect of good health. Taking care of our intellectual, emotional and social needs is just as important as our physical well-being.

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UNIT II

SOURCES AND FUNCTIONS OF CARBOHYDRATES

Carbohydrates are the sugars, starches and fibres found in fruits, grains, vegetables and milk products. Though often maligned in trendy diets, carbohydrates one of the basic food groups is important to a healthy life. They contain compounds of carbon, hydrogen and oxygen in the ratio 1:2:1.

Carbohydrates are found in a wide array of both healthy and unhealthy foods like bread, beans, milk, popcorn, potatoes, cookies, spaghetti, soft drinks, corn, and cherry pie. They also come in a variety of forms. The most common and abundant forms are sugars, fibers, and starches.

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Foods high in carbohydrates are an important part of a healthy diet. Carbohydrates provide the body with glucose, which is converted to energy used to support bodily functions and physical activity. But carbohydrate quality is important; some types of carbohydrate-rich foods are better than others:

 The healthiest sources of carbohydrates—unprocessed or minimally processed whole grains, vegetables, fruits and beans—promote good health by delivering vitamins, minerals, fiber, and a host of important phytonutrients.  Unhealthier sources of carbohydrates include white bread, pastries, sodas, and other highly processed or refined foods. These items contain easily digested carbohydrates that may contribute to weight gain, interfere with weight loss, and promote diabetes and heart disease.

The Healthy Eating Plate recommends filling most of your plate with healthy carbohydrates – with vegetables (except potatoes) and fruits taking up about half of your plate, and whole grains filling up about one fourth of your plate.

What’s most important is the type of carbohydrate you choose to eat because some sources are healthier than others. The amount of carbohydrate in the diet – high or low – is less important than the type of carbohydrate in the diet. For example, healthy, whole grains such as whole wheat bread, rye, barley and quinoa are better choices than highly refined white bread or French fries. (1)

Many people are confused about carbohydrates, but keep in mind that it’s more important to eat carbohydrates from healthy foods than to follow a strict diet limiting or counting the number of grams of carbohydrates consumed.

Function of carbohydrates

Carbohydrates provide fuel for the central nervous system and energy for working muscles. They also prevent protein from being used as energy source and enable fat metabolism. Also, carbohydrates are important for brain function. They are an influence on "mood, memory, etc., as well as a quick energy source." In fact, the RDA of carbohydrates is based on the amount of carbs the brain needs to function.

Simple vs. complex carbohydrates

Carbohydrates are classified as simple or complex. The difference between the two forms is the chemical structure and how quickly the sugar is absorbed and digested. Generally speaking, simple carbohydrates are digested and absorbed more quickly and easily than complex carbohydrates.

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Simple carbohydrates contain just one or two sugars, such as fructose (found in fruits) and galactose (found in milk products). These single sugars are called monosaccharides. Carbohydrates with two sugars — such as sucrose (table sugar), lactose (from dairy) and maltose (found in beer and some vegetables) — are called disaccharides, according to the NIH.

Simple carbohydrates are also in candy, soda and syrups. However, these foods are made with processed and refined sugars and do not have vitamins, minerals or fiber. They are called "empty calories" and can lead to weight gain, according to the NIH.

Complex carbohydrates (polysaccharides) have three or more sugars. They are often referred to as starchy foods and include beans, peas, lentils, peanuts, potatoes, corn, parsnips, whole-grain breads and cereals.

All carbohydrates function as relatively quick energy sources, but simple carbohydrates cause bursts of energy much more quickly than complex carbohydrates because of the quicker rate at which they are digested and absorbed. Simple carbohydrates can lead to spikes in blood sugar levels and sugar highs, while complex carbohydrates provide more sustained energy.

Studies have shown that replacing saturated fats with simple carbohydrates, such as those in many processed foods, is associated with an increased risk of heart disease and type 2 diabetes.

Sugars, starches and fibers

In the body, carbohydrates break down into smaller units of sugar, such as glucose and fructose. The small intestine absorbs these smaller units, which then enter the bloodstream and travel to the liver. The liver converts all of these sugars into glucose, which is carried through the bloodstream accompanied by insulin and converted into energy for basic body functioning and physical activity.

If the glucose is not immediately needed for energy, the body can store up to 2,000 calories of it in the liver and skeletal muscles in the form of glycogen, according to Iowa State University. Once glycogen stores are full, carbohydrates are stored as fat. If you have insufficient carbohydrate intake or stores, the body will consume protein for fuel. This is problematic because the body needs protein to make muscles. Using protein instead of carbohydrates for fuel also puts stress on the kidneys, leading to the passage of painful by-products in the urine.

Fibre is essential to digestion. Fibres promote healthy bowel movements and decrease the risk of chronic diseases such as coronary heart disease and diabetes, according to the U.S. Department of Agriculture. However, unlike sugars and starches, fibres are not absorbed in the small intestine and

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SBS, EDC Human Nutrition study material 2016-17 are not converted to glucose. Instead, they pass into the large intestine relatively intact, where they are converted to hydrogen and carbon dioxide and fatty acids. The Institute of Medicine recommends that people consume 14 grams of fibre for every 1,000 calories. Sources of fibre include fruits, grains and vegetables, especially legumes.

Carbohydrates are also found naturally in some forms of dairy and both starchy and non- starchy vegetables. For example, non-starchy vegetables like lettuces, kale, green beans, celery, carrots and broccoli all contain carbs. Starchy vegetables like potatoes and corn also contain carbohydrates, but in larger amounts. According to the American Diabetes Association, non-starchy vegetables generally contain only about 5 grams of carbohydrates per cup of raw vegetables, and most of those carbohydrates come from fibre.

Good carbohydrates vs. bad carbohydrates

Carbohydrates are found in foods you know are good for you (vegetables) and ones you know are not (doughnuts). This has led to the idea that some carbohydrates are "good" and some are "bad." Carbohydrates commonly considered bad include pastries, sodas, highly processed foods, white rice, white bread and other white-flour foods. These are foods with simple carbohydrates. Bad carbohydrates rarely have any nutritional value.

Carbohydrates usually considered good are complex carbohydrates, such as whole grains, fruits, vegetables, beans and legumes. These are not only processed more slowly, but they also contain a bounty of other nutrients.

Here is a checklist for determining if a carbohydrate is "good" or "bad."

Good carbohydrates are:

 Low or moderate in calories  High in nutrients  Devoid of refined sugars and refined grains  High in naturally occurring fiber  Low in sodium  Low in saturated fat  Very low in, or devoid of, cholesterol and trans fats

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Whereas bad carbohydrates are:

 High in calories  Full of refined sugars, like corn syrup, white sugar, honey and fruit juices  High in refined grains like white flour  Low in many nutrients  Low in fiber  High in sodium  Sometimes high in saturated fat  Sometimes high in cholesterol and trans fats

Glycemic index

Recently, nutritionists have said that it's not the type of carbohydrate, but rather the carbohydrate's glycemic index, that's important. The glycemic index measures how quickly and how much a carbohydrate raises blood sugar.

High-glycemic foods like pastries raise blood sugar highly and rapidly; low-glycemic foods raise it gently and to a lesser degree. Some research has linked high-glycemic foods with diabetes, obesity, heart disease and certain cancers, according to Harvard Medical School. On the other hand, different research has suggested that following a low-glycemic diet may not actually be helpful.

Carbohydrate benefits

The right kind of carbohydrates can be incredibly good for you. Not only are they necessary for your health, but they carry a variety of added benefits.

Mental health

Carbohydrates may be important to mental health. A study published in 2009 in the journal JAMA Internal Medicine found that people on a high-fat, low-carb diet for a year had more anxiety, depression and anger than people on a low-fat, high-carbohydrates diet. Scientists suspect that carbohydrates help with the production of serotonin in the brain.

Carbohydrates may help memory, too. A 2008 study at Tufts University had overweight women cut carbohydrates entirely from their diets for one week. Then, they tested the women's cognitive skills, visual attention and spatial memory. The women on no-carbohydrates diets did worse than overweight women on low-calorie diets that contained a healthy amount of carbohydrates.

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Weight loss

Though carbohydrates are often blamed for weight gain, the right kind of carbohydrates can actually help you lose and maintain a healthy weight. This happens because many good carbohydrates, especially whole grains and vegetables with skin, contain fibre. It is difficult to get sufficient fibre on a low- carbohydrate diet. Dietary fibre helps you to feel full, and generally comes in relatively low-calorie foods.

A study published in the Journal of Nutrition in 2009 followed middle-age women for 20 months and found that participants who ate more fibre lost weight, while those who decreased their fibre intake gained weight. Another recent study linked fat loss with low-fat diets, not low- carbohydrate ones.

Good source of nutrients

Whole, unprocessed fruits and vegetables are well known for their nutrient content. Some are even considered superfoods because of it — and all of these leafy greens, bright sweet potatoes, juicy berries, tangy citruses and crunchy apples contain carbohydrates.

One important, plentiful source of good carbohydrates is whole grains. A large study published in 2010 in the Journal of the American Dietetic Association found that those eating the most whole grains had significantly higher amounts of fibre, energy and polyunsaturated fats, as well as all micronutrients (except vitamin B12 and sodium). An additional study, published in 2014 in the journal Critical Reviews in Food Science and Nutrition, found that whole grains contain antioxidants, which were previously thought to exist almost exclusively in fruits and vegetables.

Heart health

Fibre also helps to lower cholesterol. The digestive process requires bile acids, which are made partly with cholesterol. As your digestion improves, the liver pulls cholesterol from the blood to create more bile acid, thereby reducing the amount of LDL, the "bad" cholesterol.

A study in the American Journal of Clinical Nutrition looked at the effect of whole grains on patients taking cholesterol-lowering medications called statins. Those who ate more than 16 grams of whole grains daily had lower bad-cholesterol levels than those who took the statins without eating the whole grains.

Carbohydrate deficiency

Not getting enough carbohydrates can cause problems. Without sufficient fuel, the body gets no energy. Additionally, without sufficient glucose, the central nervous system suffers, which may

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SBS, EDC Human Nutrition study material 2016-17 cause dizziness or mental and physical weakness, according to Iowa State University. A deficiency of glucose, or low blood sugar, is called hypoglycemia.

If the body has insufficient carbohydrate intake or stores, it will consume protein for fuel. This is problematic because the body needs protein to make muscles. Using protein for fuel instead of carbohydrates also puts stress on the kidneys, leading to the passage of painful by-products in the urine.

People who don't consume enough carbohydrates may also suffer from insufficient fibre, which can cause digestive problems and constipation.

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SOURCES AND FUNCTIONS OF FAT

Dietary fats are important for several health related aspects and for optimal functioning of the human body. Dietary fats are not just a source of energy; they function as structural building blocks of the body, carry fat-soluble vitamins, are involved in vital physiological processes in the body, and are indispensable for a number of important biological functions including growth and development. Fats are a source of energy in the human diet, together with carbohydrates and proteins, the other two main macronutrients. Fat is the most concentrated source providing 9 kcal per 1 gram consumed, which is more than double the energy content of protein or carbohydrate (4 kcal per gram) and more than quadruple the energy content of fibre (2 kcal per gram). Fat can be stored in the body’s fat tissue, which releases fatty acids when energy is required.

The membranes around the cells in our body physically separate the inside from the outside of the cell, and control the movement of substances in and out of the cells. They are mainly made of phospholipids, triglycerides and cholesterol. Both length and saturation of the fatty acids from phospholipids and triglycerides affect the arrangement of the membrane and thereby its fluidity. Shorter chain fatty acids and unsaturated fatty acids are less stiff and less viscous, making the membranes more flexible. This influences a range of important biological functions such as the process of endocytosis in which a cell wraps itself around a particle to allow its uptake.

The brain is very rich in fat (60%) and has a unique fatty acid composition; docosahexaenoic acid (DHA) is the major brain fatty acid. The lipids of the retina also contain very high concentrations of DHA.

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Carrier of vitamins

In the diet, fat is a carrier for the fat-soluble vitamins A, D, E and K, and supports their absorption in the intestine. Consuming sufficient amounts of fatty foods that contain these vitamins is thus essential for adequate intake of these micronutrients.

Other biological functions

Our bodies cannot produce the polyunsaturated fatty acids (PUFA) linoleic acid (LA) and alpha linolenic acid (ALA). Without these essential fatty acids some vital functions would be compromised, thus they must be provided by the diet. LA and ALA can be converted to longer chain fatty acids and compounds with hormone-like or inflammatory properties (such as prostaglandins or leukotrienes, respectively). As such, essential fatty acids are involved in many physiological processes such as blood clotting, wound healing and inflammation. Although the body is able to convert LA and ALA into the long chain versions arachidonic acid (AA), eicosapentaenoic acid (EPA), and, to a lesser extent, to docosahexaenoic acid (DHA), this conversion seems limited. The longer chain fatty acids EPA and DHA are said to be “conditionally essential” and it is recommended to consume direct sources of these particular long chain fatty acids. The richest source of EPA and DHA is oily fish, including anchovy, salmon, tuna and mackerel.

Dietary recommendations for fats

Historically, dietary recommendations focussed on the prevention of nutrient deficiencies. These guidelines are meant to advise people on a healthy diet that ensures adequate intakes of all nutrients. More recently, with higher prevalence of obesity and chronic diseases, nutrition recommendations have shifted to address food overconsumption and prevention of chronic (metabolic) diseases.

Generally, dietary advice for bodyweight management includes controlling total calorie intake, and recommends increasing consumption of lean meat, low-fat dairy, fruit and vegetables, whole grain cereals and fish. For dietary fats, it has been suggested that changing the type of fats consumed (i.e. saturated fat replaced by unsaturated fat), or changing the type in combination with an overall reduction of fat are protective against cardiovascular events.

Total fat

Most authorities recommended intake for total dietary fat in adults ranges between 20-35%. This means that it is advised that 20-35% of the total daily energy intake should come from dietary sources of fats. Fat has many essential biological functions, so the total consumption should not be

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SBS, EDC Human Nutrition study material 2016-17 lower than 15-20%. Moreover, diets that are low in fat (≤20%E) may adversely affect blood lipids by lowering HDL and increasing triglycerides, and may lead to an inadequate intake of essential fatty acids. The upper limit for fat intake aims to ensure that people do not consume too many daily calories as fat, since it is the most energy-dense macronutrient.

Saturated fatty acids

The advice to keep saturated fatty acid (SFA) consumption below 10%E stems from its LDL cholesterol raising potential and effects on cardiovascular disease (CVD) risk. Some guidelines suggest keeping saturated fat intake as low as possible. There is a wide consensus that the most positive effects are seen when saturated fatty acids are replaced by PUFA.

Trans fatty acids

The recommendations for trans fatty acids (TFA) are mainly to keep the intake either as low as possible, or below 1%E.6 It has been convincingly shown that TFA adversely affect blood lipids and increase subsequent CVD risk. In contrast to 10-15 years ago, the vast majority of the food products analysed recently for TFA content in Western Europe, do not contain high levels of TFA, and do not pose a major health risk. Although in some Eastern European countries TFA levels were found to be significantly higher.

Monounsaturated fatty acids

The majority of dietary recommendations do not have specific advice for monounsaturated fatty acids (MUFA). The Food and Agricultural Organization (FAO) indicated that the MUFA recommendation can be obtained with the following calculation: total fat [%E] – SFA [%E] – PUFA [%E] – TFA [%E], with 15 -20%E as a result.

Polyunsaturated fatty acids

Not all (inter)national authorities have specific recommendations for total PUFA, but some do. Instead, they have set recommendations for the specific fatty acids, including the n-3 fatty acids ALA, EPA, DHA and EPA+DHA, and the n-6 fatty acids LA and in some cases also AA. These recommendations vary considerably among the different countries, organisations, and consumer age groups, and are expressed either in ‘%E’ or in ‘g/day’. The reason for these differences may be because some organisations have focussed on avoiding deficiencies while others have established the recommendations in order to prevent chronic diseases.

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Cholesterol

Most authoritative bodies do not provide a maximum amount for cholesterol consumption. When they do, the advice is to not exceed 300 mg/day.6 The most recent scientific publications point out that in healthy individuals, dietary cholesterol has little impact on blood cholesterol levels

Types of Fat

Unsaturated fats

Unsaturated fats, which are liquid at room temperature, are considered beneficial fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles. Unsaturated fats are predominantly found in foods from plants, such as vegetable oils, nuts, and seeds.

There are two types of “good” unsaturated fats:

1. Monounsaturated fats are found in high concentrations in:

 Olive, peanut, and canola oils  Avocados  Nuts such as almonds, hazelnuts, and pecans  Seeds such as pumpkin and sesame seeds

2. Polyunsaturated fats are found in high concentrations in

 Sunflower, corn, soybean, and flaxseed oils

 Walnuts

 Flax seeds

 Fish

 Canola oil – though higher in monounsaturated fat, it’s also a good source of polyunsaturated fat.

 Omega-3 fats are an important type of polyunsaturated fat. The body can’t make these, so they must come from food.

 An excellent way to get omega-3 fats is by eating fish 2-3 times a week.

 Good plant sources of omega-3 fats include flax seeds, walnuts, and canola or soybean oil.

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 Higher blood omega-3 fats are associated with lower risk of premature death among older adults, according to a study by HSPH faculty.

 Read more about omega-3 fats in our Ask the Expert with Dr. Frank Sacks.

 Most people don’t eat enough healthful unsaturated fats. The American Heart Association suggests that 8-10 percent of daily calories should come from polyunsaturated fats, and there is evidence that eating more polyunsaturated fat—up to 15 percent of daily calories—in place of saturated fat can lower heart disease risk.

 Dutch researchers conducted an analysis of 60 trials that examined the effects of carbohydrates and various fats on blood lipid levels. In trials in which polyunsaturated and monounsaturated fats were eaten in place of carbohydrates, these good fats decreased levels of harmful LDL and increased protective HDL.

 More recently, a randomized trial known as the Optimal Macronutrient Intake Trial for Heart Health (OmniHeart) showed that replacing a carbohydrate-rich diet with one rich in unsaturated fat, predominantly monounsaturated fats, lowers blood pressure, improves lipid levels, and reduces the estimated cardiovascular risk.

Saturated Fats

All foods containing fat have a mix of specific types of fats. Even healthy foods like chicken and nuts have small amounts of saturated fat, though much less than the amounts found in beef, cheese, and ice cream. Saturated fat is mainly found in animal foods, but a few plant foods are also high in saturated fats, such as coconut, coconut oil, palm oil, and palm kernel oil.

 The Dietary Guidelines for Americans recommends getting less than 10 percent of calories each day from saturated fat.

 The American Heart Association goes even further, recommending limiting saturated fat to no more than 7 percent of calories.

Cutting back on saturated fat will likely have no benefit, however, if people replace saturated fat with refined carbohydrates. Eating refined carbohydrates in place of saturated fat does lower “bad” LDL cholesterol, but it also lowers the “good” HDL cholesterol and increases triglycerides. The net effect is as bad for the heart as eating too much saturated fat.

In the United States, the biggest sources of saturated fat in the diet are

 Pizza and cheese

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 Whole and reduced fat milk, butter and dairy desserts

 Meat products (sausage, bacon, beef, hamburgers)

 Cookies and other grain-based desserts

 Mexican fast food dishes

Though decades of dietary advice suggested saturated fat was harmful, in recent years that idea has begun to evolve. Several studies suggest that eating diets high in saturated fat do not raise the risk of heart disease, with one report analyzing the findings of 21 studies that followed 350,000 people for up to 23 years.

Investigators looked at the relationship between saturated fat intake and coronary heart disease (CHD), stroke, and cardiovascular disease (CVD). Their controversial conclusion: “There is insufficient evidence from prospective epidemiologic studies to conclude that dietary saturated fat is associated with an increased risk of CHD, stroke, or CVD.”

A well-publicized 2014 study questioned the link between saturated fat and heart disease, but HSPH nutrition experts determined the paper to be seriously misleading. In order to set the record straight, Harvard School of Public Health convened a panel of nutrition experts and held a teach-in, “Saturated or not: Does type of fat matter?“

The overarching message is that cutting back on saturated fat can be good for health if people replace saturated fat with good fats, especially, polyunsaturated fats. Eating good fats in place of saturated fat lowers the “bad” LDL cholesterol, and it improves the ratio of total cholesterol to “good” HDL cholesterol, lowering the risk of heart disease.

Eating good fats in place of saturated fat can also help prevent insulin resistance, a precursor to diabetes. So while saturated fat may not be as harmful as once thought, evidence clearly shows that unsaturated fat remains the healthiest type of fat.

Trans Fats

Trans fatty acids, more commonly called trans fats, are made by heating liquid vegetable oils in the presence of hydrogen gas and a catalyst, a process called hydrogenation.

 Partially hydrogenating vegetable oils makes them more stable and less likely to become rancid. This process also converts the oil into a solid, which makes them function as margarine or shortening.

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 Partially hydrogenated oils can withstand repeated heating without breaking down, making them ideal for frying fast foods.  For these reasons, partially hydrogenated oils became a mainstay in restaurants and the food industry – for frying, baked goods, and processed snack foods and margarine.

Partially hydrogenated oil is not the only source of trans fats in our diets. Trans fats are also naturally found in beef fat and dairy fat in small amounts. Eliminating industrial-produced trans fats from the U.S. food supply could prevent between 6 and 19 percent of heart attacks and related deaths, or as much as 200,000 each year.

Trans fats are worse for cholesterol levels than saturated fats because they:

 Raise bad LDL and lower good HDL

 Create inflammation, a reaction related to immunity which has been implicated in heart disease, stroke, diabetes, and other chronic conditions

 Contribute to insulin resistance

 Can have harmful health effects even in small amounts, for each additional 2 percent of calories from trans-fat consumed daily, the risk of coronary heart disease increases by 23 percent.

Cholesterol

All animal cells contain cholesterol, a lipid that plays a role in the membrane’s fluidity and permeability. Cholesterol is also a precursor of vitamin D, adrenal and sex steroid hormones, and bile salts that emulsify and enhance absorption of fats in the intestine. The main dietary sources of cholesterol are cheese, eggs, beef, pork, poultry and (shell) fish.

Dietary cholesterol helps to maintain a stable pool of cholesterol, but cholesterol is also synthesised by the liver. The human body regulates its cholesterol status. When the cholesterol intake is very low (as in vegans who consume no animal products), both gut absorption and synthesis increase. When cholesterol intake is high, the body's synthesis is suppressed and excretion via bile salts is increased. The amount of cholesterol, which passes daily through the small intestine, which is the sum of dietary cholesterol and produced cholesterol, is between 1 and 2 g. The average cholesterol intake in Europe is 200-300 mg/day, meaning that the body’s production is significantly higher. The blood cholesterol level is the net result of the absorption in the gut and the synthesis in the liver, minus the excretion via the faeces (as cholesterol, bile salts and products resulting from bacterial transformation) and the use of cholesterol by cells.

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Importantly, for most people, eating foods that contain cholesterol has little effect on blood cholesterol levels. However, a small number of people (15-25% of the population) may be 'hyper- responders' to dietary cholesterol, and are advised to limit their cholesterol intake.

Cholesterol in the blood is carried by lipoproteins: LDL (low density lipoprotein) and HDL (high density lipoprotein).

Essential Fatty Acids (EFA)

The body can synthesize most of the fats it needs from the diet. However, two essential fatty acids, linoleic and alpha-linolenic, cannot be synthesized in the body and must be obtained from food. These basic fats, found in plant foods, are used to build specialized fats called omega-3 and omega-6 fatty acids.

Both omega-6 and omega-3 fatty acids are important structural components of cell membranes, serve as precursors to bioactive lipid mediators, and provide a source of energy. Long- chain omega-3 PUFA in particular exert anti-inflammatory effects and it is recommended to increase their presence in the diet.

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SOURCES AND FUNCTIONS OF PROTEINS

Proteins and Essential Amino Acids

Proteins are a group of large complex molecules that serve as structural components and regulate a large variety of bodily functions. The constituents of proteins are amino acids; there are 20 naturally occurring amino acids, which can be assembled in various combinations and numbers to make the thousands of different types of proteins. During digestion, proteins may be broken down into their component amino acids by enzymes in the digestive tract and transported in the bloodstream to the liver and body tissues.

Functions of Proteins

Essential Amino Acids

The necessary role of dietary proteins is to supply amino acids so that the body can construct human proteins. All 20 amino acids are necessary for protein synthesis, and cells in the human body have the ability to synthesize 11 amino acids from raw materials; the other nine cannot be made by the body. These nine are called the essential amino acids and must come from the diet. It is important to note that these essential amino acids cannot be stored by the body, and they must be present simultaneously in the diet. For this reason it is critical that the body receives all the essential amino acids in a single day. Persistent lack of these essential amino acids prevents synthesis of necessary proteins and results in protein-deficiency diseases.

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Essential and non-essential amino acids

Complete Proteins

Complete proteins contain all the essential amino acids and in the right proportions. Almost all proteins derived from animals are complete proteins whereas proteins derived from plants are usually incomplete, deficient in one or more essential amino acids. Although plant proteins are incomplete, the essential amino acid requirements can be met by combining complementary plant proteins. For example, the traditional diet of the native peoples of Mexico, beans and corn, contains complementary protein sources. The beans are low in methionine but adequate in tryptophan and lysine, but corn, which is poor in tryptophan and lysine, contains adequate amounts of methionine. Although we have an absolute requirement for the essential amino acids, the actual amount of protein required by humans is a small percentage of our nutrient needs. It is recommended that approximately 10% (a range from 8% to 10%) of our total caloric intake be provided by proteins. On the basis of this percentage, individuals on a 2,000-kilocalorie diet should have 50 grams of protein per day; those on a 1,600-kilocalorie diet, 40 grams of protein per day; and those on a 2,200- kilocalorie diet, 55 grams of protein.

The following daily protein intakes have been recommended for specific age groups:

 Infants under 1 year - 14 grams;  Children 1 to 4 years old - 16 grams;  Pregnant women - 60 grams and;  Nursing mothers - 65 grams.

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Proteins can be assigned a numerical value that reflects how well they supply the essential amino acids. The protein in eggs has been assigned a biological value of 100, and all other foods are given values using egg protein as the reference standard. Another factor that needs to be considered is the digestibility of a particular protein. Some proteins cannot be broken down completely; that is, the amino acids are not fully released during digestion. This incomplete breakdown reduces the dietary value of the protein. For example, when digestibility is taken into account, even egg protein, which is considered as the perfect protein source, drops to a value of 94. High-quality proteins contain all the essential amino acids in the right proportions and are fully digestible, freeing their amino acids, which are then absorbed into the blood and transported to the body’s cells.

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UNIT III

ENERGY UNITS

Energy is not a nutrient but is required in the body for metabolic processes, physiological functions, muscular activity, heat production, growth and synthesis of new tissues. It is released from food components by oxidation. The main sources of energy are carbohydrates, proteins, fats and, to a lesser degree, alcohol.

The unit of energy is the kilojoule (kJ) or megajoule (1 MJ = 1,000 kJ) and 4.18 kilojoules are equal to 1 kilocalorie.

KILOCALORIES

The term is used to represent the amount of energy required to raise the temperature of a litre of water by one degree centigrade at sea level. The "calorie" we refer to in food is actually kilocalorie. One kilocalorie is the same as one Calorie (C). A kilocalorie is the amount of heat required to raise the temperature of 1 kilogram of water by one degree Celsius.

Although these units are part of the metric system, they have been superseded in the International System of Units by the joule. One small calorie is approximately 4.2 joules (so one large calorie is about 4.2 kilojoules). The factor used to convert calories to joules at a given temperature is numerically equivalent to the specific heat capacity of water expressed in joules per kelvin per gram or per kilogram. The precise conversion factor depends on the definition adopted. In spite of its non-official status, the large calorie is still widely used as a unit of food energy. The small calorie is also often used for measurements in chemistry, although the amounts involved are typically recorded in kilocalories.

MEGA JOULES

It’s a unit of energy, like the calorie. The megajoule (MJ) is equal to one million (106) joules, or about 240 Calories (Approximately) or approximately the kinetic energy of a one megagram (tonne) vehicle moving at 160 km/h. One kilowatt hour of electricity is 3.6 megajoules.

The Joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the energy transferred (or work done) to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N·m). It is also the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.

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ENERGY VALUE OF FOODS

Allowing for intestinal absorption and for the nitrogenous parts of protein that cannot be completely oxidised, the average amount of energy released ranges from approximately 16.7 kJ/g for carbohydrates or protein to 29.3 kJ/g for alcohol and 37.7 kJ/g for fats.

Humans need energy for basal metabolism which comprises a set of functions necessary for life such as cell metabolism, synthesis and metabolism of enzymes and hormones, transport of substances around the body, maintenance of body temperature and ongoing functioning of muscles including the heart, and brain function. The amount of energy needed for this purpose in a defined period of time is called the Basal Metabolic Rate (BMR). BMR represents about 45–70% of daily energy expenditure, depending on age, gender, body size and composition. Physical activity is the most variable determinant of energy need and is the second largest user of energy after BMR. Humans perform a number of physical activities including the obligatory demands of an individual’s economic, social and cultural environment (eg occupational, schoolwork, housework etc) or discretionary activity (eg energy expended for optional exercise or sport, or in additional social or cultural interactions).

Energy is also required to process food into nutrients resulting in increases in heat production and oxygen consumption often described by the terms 'dietary-induced thermogenesis', 'specific dynamic action of food' or 'thermic effect of feeding'. The metabolic response to food increases the BMR by about 10% over the day in people eating a mixed diet. Growth also requires energy for synthesis of tissues. In the first three months of life, growth uses about 35% of total energy needs. This falls to 5% at 12 months, less than 2% in the second year of life, 1–2% until mid-adolescence and zero by 20 years of age. Additional energy is also needed in pregnancy and lactation to cover the needs of the growing foetus, the placenta and expanding maternal tissues and additional maternal effort at rest and in physical activity, as well as the production of breast milk.

The best method of assessing energy needs is the doubly-labelled water technique. When this method is applied over a 24-hour period, it includes estimates of dietary-induced thermogenesis and the energy cost of tissue synthesis. For adults, this equates to daily energy requirements. The additional needs in infancy and childhood, in adolescence, pregnancy and lactation need to be estimated from growth velocity or weight gain equations, composition of weight gain and average volume and composition of breast milk. When direct data are not available, factorial estimates based on time allocated to habitually performed, activities and knowledge of the energy cost of these activities may be used.

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As energy requirements vary with age, gender, body size and activity, recommendations are needed for each age and gender group.

Recommendations for energy intake differ from those for nutrient intake in that:

 they are not increased to cover the needs of most members of the group or population, as this level of intake would lead to overweight or obesity in most people.  there are differences between the actual energy requirements needed to maintain current body size and level of physical activity and the desirable energy requirements needed to maintain body size and levels of physical activity consistent with good health. Desirable energy requirements may be lower than actual requirements for people who are overweight or obese. Desirable requirements may be higher than actual for inactive people. For people who are both overweight/obese and physically inactive, the difference between actual and desirable will depend on the balance between degree of overweight and level of inactivity.  they can be applied cautiously to individuals, using estimates of energy expenditure. However, predictive estimates are much less accurate for individuals than for groups, and variations in energy expenditure can be large, even between apparently similar individuals.  there is wide inter-individual variation in the behavioural, physiologic and metabolic components of energy needs. The average energy intake recommended for a defined group cannot be applied to other groups or individuals who differ from the defined group average in gender, age, body size, activity level and possibly other factors.

Two separate terms can therefore be used to express and determine Estimated Energy Requirements (EER):

 The Estimated Energy Requirement for Maintenance (EERM, or actual energy requirement) is the dietary energy intake that is predicted to maintain energy balance (plus extra needs for pregnancy, lactation and growth) in healthy individuals or groups of individuals at current levels of body size and level of physical activity.  The Desirable Estimated Energy Requirement (DEER, or energy reference value) is the dietary energy intake that is predicted to maintain energy balance (plus extra needs for pregnancy, lactation and growth) in healthy individuals or groups of individuals of a defined gender, age, weight, height and level of physical activity consistent with good health and/or development.

Use of, and distinction between, these two terms is necessary because of the various ways in which estimates of energy requirements are used and because of the risk of over-prescription of desirable energy intakes in people who do not follow recommendations for increased physical

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RELATIONSHIP BETWEEN OXYGEN USED AND CALORIFIC VALUE

Food energy is chemical energy that animals (including humans) derive from their food and molecular oxygen through the process of cellular respiration. (Cellular respiration involves either the process of joining oxygen from air with the molecules of food (aerobic respiration) or the process of reorganizing the atoms within the molecules (anaerobic respiration).

Using the International System of Units, researchers measure energy in joules (J) or in its multiples; the kilojoule (kJ) is most often used for food-related quantities. An older metric system unit of energy, still widely used in food-related contexts, is the calorie; more precisely, the "food calorie", "large calorie" or kilocalorie (kcal or Cal), equal to 4.184 kilojoules. (Contrast the "small calorie" (cal), equal to 1/1000 of a food calorie, that is often used in chemistry and in physics.) Within the European Union, both the kilocalorie ("kcal") and kilojoule ("kJ") appear on nutrition labels. In many countries, only one of the units is displayed; in the US and Canada labels spell out the unit as "calorie" or as "Calorie".

Fats and ethanol have the greatest amount of food energy per mass, 37 and 29 kJ/g (8.8 and 6.9 kcal/g), respectively. Proteins and most carbohydrates have about 17 kJ/g (4.1 kcal/g). The differing energy density of foods (fat, alcohols, carbohydrates and proteins) lies mainly in their varying proportions of carbon, hydrogen, and oxygen atoms: For food of elemental composition

CcHhOoNn, the heat of combustion underlying the food energy is 100 kcal/g (c + 0.3 h – 0.5 o)/(12 c + h + 16 o +14 n) to a good approximation (±3%). Carbohydrates that are not easily absorbed, such as fibre, or lactose in lactose-intolerant individuals, contribute less food energy. Polyols (including sugar alcohols) and organic acids contribute 10 kJ/g (2.4 kcal/g) and 13 kJ/g (3.1 kcal/g) respectively. The amount of water, fat, and fibre in foods determines those foods' energy density.

Theoretically, one could measure food energy in different ways, using (say) the Gibbs free energy of combustion, or the amount of ATP generated by metabolizing the food. However, the convention is to use the heat of the oxidation reaction, with the water substance produced being in the liquid phase. Conventional food energy is based on heats of combustion in a bomb calorimeter and corrections that take into consideration the efficiency of digestion and absorption and the production of urea and other substances in the urine.

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Each food item has a specific metabolizable energy intake (MEI). This value can be approximated by multiplying the total amount of energy associated with a food item by 85%, which is the typical amount of energy actually obtained by a human after respiration has been completed. In animal nutrition, where energy is a critical element of the economics of meat production, researchers may determine a specific metabolizable energy for each component (protein, fat, etc.) of each ingredient of the feed.

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Energy density Food component kJ/g kcal/g

Fat 37 9

Ethanol (drinking alcohol) 29 7

Proteins 17 4

Carbohydrates 17 4

Organic acids 13 3

Polyols (sugar alcohols, sweeteners) 10 2.4

Fibre 8 2

ENERGY BASAL METABOLISM

The minimum amount of energy required to maintain vital functions in an organism at complete rest, measured by the basal metabolic rate in a fasting individual.

Basal metabolism is the number of calories a body burns for energy even when sleeping. This energy is used to support life-sustaining jobs, from breathing and pumping blood to maintaining body temperature. The body also needs constant energy to make sure it has the right amount of fluids and essential substances for metabolism. For example, the nerves and muscles can’t work without a specific concentration of potassium and sodium. Monitoring and regulating these two minerals accounts for about 20 to 40 percent of the energy used when a person is at rest.

CALCULATING BASAL METABOLIC RATE (BMR)

The basal metabolic rate can be calculated by following a formula based on height, weight and age, but this only produces an estimate. To obtain the precise rate, we must consider all of our individual factors, use specialized equipment and obtain measurements under strict conditions, such as after a good night’s sleep and while fasting. The basal metabolic rate only accounts for about 70 percent of the calories used by the body. The total amount of energy a person burns is determined by the basal metabolic rate plus the level of physical activity and the calories burned when that individual digests food and absorb nutrients.

BMR is measured under very restrictive circumstances when a person is awake. An accurate BMR measurement requires that the person's sympathetic nervous system not be stimulated, a

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SBS, EDC Human Nutrition study material 2016-17 condition which requires complete rest. A more common measurement, which uses less strict criteria, is resting metabolic rate (RMR).

BMR is the minimal rate of energy expenditure per unit time by endothermic animals at rest. It is reported in energy units per unit time ranging from watt (Joule/second) to ml O2/min or Joule per hour per kg body mass J/(h.kg)). Proper measurement requires a strict set of criteria be met. These criteria include being in a physically and psychologically undisturbed state, in a thermally neutral environment, while in the post-absorptive state (i.e., not actively digesting food).

BMR estimation formulas

Several prediction equations exist. Historically, the most notable one was the Harris-Benedict equation, which was created in 1919.

In each of the formulas:

 P is total heat production at complete rest,  m is mass (kg),  h is height (cm), and  a is age (years)

The Original Harris-Benedict Equation:

For men,

For women,

The difference in BMR for men and women is mainly due to differences in body weight. For example, a 55-year-old woman weighing 130 lb (59 kg) and 5 feet 6 inches (168 cm) tall would have a BMR of 1272 kcal per day or 53 kcal/h (61.3 watts).and with the difference in BMR for men and women being mainly due to differences in body weight.

In 1984, the original Harris-Benedict equations were revised using new data. In comparisons with actual expenditure, the revised equations were found to be more accurate.

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The Revised Harris-Benedict Equation:

For men,

For women,

The Mifflin St Jeor Equation:

where s is +5 for males and −161 for females.

According to this formula, the woman in the example above has a BMR of 1204 kcal per day.

These formulas are based on body weight, which does not take into account the difference in metabolic activity between lean body mass and body fat. Other formulas exist which take into account lean body mass, two of which are the Katch-McArdle formula, and Cunningham formula. The Katch-McArdle formula is used to predict Resting Daily Energy Expenditure (RDEE). The Cunningham formula is commonly attributed as being used to predict RMR instead of BMR, however the formulas provided by Katch-McArdle and Cunningham are the same.

The Katch-McArdle Formula (Resting Daily Energy Expenditure):

where LBM is the lean body mass in kg.

According to this formula, if a woman has a body fat percentage of 30%, her RDEE would be 1263 kcal per day.

FACTORS AFFECTING BASAL METABOLISM

Several factors influence the basal metabolism. Some people have a higher metabolic rate thanks to their genes. Muscles burn three times more calories than fat even while a person is sleeping, so the proportion of muscle to fat changes the metabolic rate. Age makes a difference because the body loses muscle mass with aging, which slows down metabolism. When a person

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SBS, EDC Human Nutrition study material 2016-17 doesn’t consume enough calories to support the minimum energy needs, the metabolism slows down by up to 30 percent. A fever increases the body’s metabolic rate by 7 percent for every 0.5 degree Centigrade over normal body temperature. When the thyroid gland doesn’t produce the right amount of hormones, metabolic rate may drop by 30 to 40 percent.

TEMPERATURE REGULATION OF THE HUMAN BODY

The human body has the remarkable capacity for regulating its core temperature somewhere between 98°F and 100°F when the ambient temperature is between approximately 68°F and 130°F according to Guyton. This presumes a nude body and dry air.

The external heat transfer mechanisms are radiation, conduction and convection and evaporation of perspiration. The process is far more than the passive operation of these heat transfer mechanisms, however. The body takes a very active role in temperature regulation.

The temperature of the body is regulated by neural feedback mechanisms which operate primarily through the hypothalmus. The hypothalmus contains not only the control mechanisms, but also the key temperature sensors. Under control of these mechanisms, sweating begins almost precisely at a skin temperature of 37°C and increases rapidly as the skin temperature rises above this value. The heat production of the body under these conditions remains almost constant as the skin temperature rises. If the skin temperature drops below 37°C a variety of responses are initiated to conserve the heat in the body and to increase heat production. These include

 Vasoconstriction to decrease the flow of heat to the skin.  Cessation of sweating.  Shivering to increase heat production in the muscles.  Secretion of norepinephrine, epinephrine, and thyroxine to increase heat production  In lower animals, the erection of the hairs and fur to increase insulation.

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TOTAL ENERGY REQUIREMENT

Human energy requirements are estimated from measures of energy expenditure plus the additional energy needs for growth, pregnancy and lactation. Recommendations for dietary energy intake from food must satisfy these requirements for the attainment and maintenance of optimal health, physiological function and well-being. The latter (i.e. well-being) depends not only on health, but also on the ability to satisfy the demands imposed by society and the environment, as well as all the other energy-demanding activities that fulfil individual needs.

Energy balance is achieved when input (i.e. dietary energy intake) is equal to output (i.e. total energy expenditure), plus the energy cost of growth in childhood and pregnancy, or the energy cost to produce milk during lactation. When energy balance is maintained over a prolonged period, an individual is considered to be in a steady state. This can include short periods during which the day- to-day balance between intake and expenditure does not occur. An optimal steady state is achieved when energy intake compensates for total energy expenditure and allows for adequate growth in children, and pregnancy and lactation in women, without imposing metabolic, physiological or behavioural restrictions that limit the full expression of a person’s biological, social and economic potential.

Within certain limits, humans can adapt to transient or enduring changes in energy intake through possible physiological and behavioural responses related to energy expenditure and/or changes in growth. Energy balance is maintained, and a new steady state is then achieved. However, adjustments to low or high energy intakes may sometimes entail biological and behavioural penalties, such as reduced growth velocity, loss of lean body mass, excessive accumulation of body

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An adequate, healthy diet must satisfy human needs for energy and all essential nutrients. Furthermore, dietary energy needs and recommendations cannot be considered in isolation of other nutrients in the diet, as the lack of one will influence the others. Thus, the following definitions are based on the assumption that requirements for energy will be fulfilled through the consumption of a diet that satisfies all nutrient needs.

Energy requirement is the amount of food energy needed to balance energy expenditure in order to maintain body size, body composition and a level of necessary and desirable physical activity consistent with long-term good health. This includes the energy needed for the optimal growth and development of children, for the deposition of tissues during pregnancy, and for the secretion of milk during lactation consistent with the good health of mother and child.

The recommended level of dietary energy intake for a population group is the mean energy requirement of the healthy, well-nourished individuals who constitute that group.

Based on these definitions, a main objective for the assessment of energy requirements is the prescription of dietary energy intakes that are compatible with long-term good health. Therefore, the levels of energy intake recommended by this expert consultation are based on estimates of the requirements of healthy, well-nourished individuals. It is recognized that some populations have particular public health characteristics that are part of their usual, "normal" life. Foremost among these are population groups in many developing countries where there are numerous infants and children who suffer from mild to moderate degrees of malnutrition and who experience frequent episodes of infectious diseases, mostly diarrhoeal and respiratory infections. Special considerations are made in this report for such sub-populations.

DAILY ENERGY REQUIREMENTS AND DAILY ENERGY INTAKES

Energy requirements and recommended levels of intake are often referred to as daily requirements or recommended daily intakes. These terms are used as a matter of convention and convenience, indicating that the requirement represents an average of energy needs over a certain number of days, and that the recommended energy intake is the amount of energy that should be ingested as a daily average over a certain period of time. There is no implication that exactly this amount of energy must be consumed every day, nor that the requirement and recommended intake are constant, day after day. Neither is there any biological basis for defining the number of days over

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SBS, EDC Human Nutrition study material 2016-17 which the requirement or intake must be averaged. As a matter of convenience, taking into account that physical activity and eating habits may vary on some days of the week, periods of seven days are often used when estimating the average daily energy expenditure and recommended daily intake.

BALANCED DIET FORMULATION

Human nutrition refers to the provision of essential nutrients necessary to support human life and health. Generally, people can survive up to 40 days without food, a period largely depending on the amount of water consumed, stored body fat, muscle mass and genetic factors. Good nutrition is an important part of leading a healthy lifestyle. Combined with physical activity, your diet can help you to reach and maintain a healthy weight, reduce your risk of chronic diseases (like heart disease and cancer), and promote your overall health.

A balanced diet is one that gives your body the nutrition it needs to function properly. In order to get truly balanced nutrition, you should obtain the majority of your daily calories from fresh fruits and vegetables, whole grains, and lean proteins. There is good evidence that eating a healthy diet can reduce your risk of obesity and illnesses such as diabetes, heart disease, stroke, osteoporosis and some types of cancer. The food you eat contains several different types of nutrients, which are all required for the many vital processes in your body.

The eatwell plate shows that to have a healthy, balanced diet, people should try to eat: plenty of fruits and vegetables, plenty of starchy foods, such as bread, rice, potatoes and pasta, some meat, fish, eggs, beans and other non-dairy sources of protein.

Nutrition is a basic human need and a prerequisite to a healthy life. A proper diet is essential from the very early stages of life for proper growth, development and to remain active. Food consumption, which largely depends on production and distribution, determines the health and nutritional status of the population. The recommended dietary allowances (RDA) are nutrient-centred and technical in nature. Apart from supplying nutrients, foods provide a host of other components (non-nutrient phytochemicals) which have a positive impact on health. Since people consume food, it is essential to advocate nutrition in terms of foods, rather than nutrients. Emphasis has, therefore, been shifted from a nutrient orientation to the food-based approach for attaining optimal nutritional status. Dietary guidelines are a translation of scientific knowledge on nutrients into specific dietary advice. They represent the recommended dietary allowances of nutrients in terms of diets that should be consumed by the population. The guidelines promote the concept of nutritionally adequate diets and healthy lifestyles from the time of conception to old age.

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Formulation of dietary goals and specific guidelines would help in providing required guidance to people in ensuring nutritional adequacy. The dietary guidelines could be directly applied for general population or specific physiological or high risk groups to derive health benefits. They may also be used by medical and health personnel, nutritionists and dietitians. The guidelines are consistent with the goals set in national policies on Agriculture, Health and Nutrition. The dietary guidelines ought to be practical, dynamic and flexible, based on the prevailing situation. Their utility is influenced by the extent to which they reflect the social, economic, agricultural and other environmental conditions. The guidelines can be considered as an integral component of the country's comprehensive plan to reach the goals specified in the National Nutrition Policy.

The major food issues of concern are insufficient/ imbalanced intake of foods/nutrients. The common nutritional problems of public health importance in India are low birth weight, protein energy malnutrition in children, chronic energy deficiency in adults, micronutrient malnutrition and diet-related non-communicable diseases. However, diseases at the either end of the spectrum of malnutrition (under and over-nutrition) are important. Recent evidences indicate that undernutrition in utero may set the pace for diet-related chronic diseases in later life. Population explosion, demographic changes, rapid urbanization and alterations in traditional habits contribute to the development of certain unhealthy dietary practices and physical inactivity, resulting in diet-related chronic diseases.

The dietary guidelines emphasize promotion of health and prevention of disease, of all age groups with special focus on vulnerable segments of the population such as infants, children and adolescents, pregnant and lactating women and the elderly. Other related factors, which need consideration, are physical activity, health care, safe water supply and socio-economic development, all of which strongly influence nutrition and health.

A variety of foods, which are available and are within the reach of the common man, can be selected to formulate nutritionally adequate diets. While there are only four accepted basic food groups, in India, there are a variety of food preparations and culinary practices. Different cereals/millets are used as staple food, apart from a variety of cereal/millet/pulse combinations in different regions of India. The cooking oils and fat used are of several kinds.

DIETARY GOALS

1. Maintenance of a state of positive health and optimal performance in populations at large by maintaining ideal body weight. 2. Ensuring adequate nutritional status for pregnant women and lactating mothers.

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3. Improvement of birth weights and promotion of growth of infants, children and adolescents to achieve their full genetic potential. 4. Achievement of adequacy in all nutrients and prevention of deficiency diseases. 5. Prevention of chronic diet-related disorders. 6. Maintenance of the health of the elderly and increasing the life expectancy.

DIETARY GUIDELINES

Right nutritional behaviour and dietary choices are needed to achieve dietary goals. The following 15 dietary guidelines provide a broad framework for appropriate action:

1. Eat variety of foods to ensure a balanced diet. 2. Ensure provision of extra food and healthcare to pregnant and lactating women. 3. Promote exclusive breastfeeding for six months and encourage breastfeeding till two years or as long as one can. 4. Feed home based semi solid foods to the infant after six months. 5. Ensure adequate and appropriate diets for children and adolescents, both in health and sickness. 6. Eat plenty of vegetables and fruits. 7. Ensure moderate use of edible oils and animal foods and very less use of ghee/ butter/ vanaspati. 8. Avoid overeating to prevent overweight and obesity. 9. Exercise regularly and be physically active to maintain ideal body weight. 10. Restrict salt intake to minimum. 11. Ensure the use of safe and clean foods. 12. Adopt right pre-cooking processes and appropriate cooking methods. 13. Drink plenty of water and take beverages in moderation. 14. Minimize the use of processed foods rich in salt, sugar and fats. 15. Include micronutrient-rich foods in the diets of elderly people to enable them to be fit and active.

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UNIT IV

MINERAL NUTRITION

Essential minerals which are inorganic substances are classified as macro and micronutrients based on the amount needed by humans per day. Macro minerals are those which are vital to health and that are required in the diet by more than 100 mg per day and those required in the diet less than 20 mg per day are called micro minerals or trace minerals. The essential macro minerals are Calcium, Phosphorous, Magnesium, Sulphur, Potassium and Chloride. Important micro minerals of relevance in human nutrition are Iron, Zinc, Copper, Sodium, Cobalt, Fluoride, Manganese, Chromium, Iodine and Molybdenum.

MACRO MINERALS

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CALCIUM AND PHOSPHORUS

Calcium is an essential element required for several life processes. The requirements of Calcium and Phosphorous are considered together as their function and requirement are closely linked. Over 99% of the Calcium and Phosphorous is present in the bones and the remaining 1% in the body fluids.

The Calcium and Phosphorous are present in the ratio of 2:1 in our body. In the skeletal system Ca and P is present in the form of hydroxyapatite crystals. Hydroxyapatite is a compound made up of calcium and phosphate that is deposited into the bone matrix to give it strength and rigidity.

Functions

1. Bone formation: The major mineral ions of the bone are Calcium, Phosphorous and Magnesium. For proper calcification of bones, (deposition of minerals on the bone matrix) which occurs during the growing years, adequate supply of these minerals is essential. 2. Tooth formation: Calcium and Phosphorous together as a compound is essential for the formation of dentin and enamel. 3. Physiological Process: a. Calcium is essential for the clotting of blood as it is required for prothrombin activation. b. Calcium regulates the permeability of the capillary walls and ion transport across the cell membranes. c. It is essential for the contraction of the heart and skeletal muscle. d. Ca regulates the excitability of the nerve fibres. e. Ca acts as an activator for enzymes such as rennin and pancreatic lipase. 4. Phosphorous is essential for the storage and release of adenosine triphosphate (ATP) molecules. 5. Phosphates play an important role as buffers to prevent changes in acidity of the body fluids. 6. Phoshpolipids are major components of cell membrane and intra cellular organelles. 7. In the DNA and RNA phosphate is an essential part of the nucleic acids.

Food sources

Among cereals ragi contains large amounts of calcium. Bengal gram whole, gingelly seeds, cumin seeds, poppy seeds, agathi, amaranth, drumstick leaves are good sources of calcium. Milk and milk products are good sources of calcium and phosphorous. Only 20 – 30 % of the calcium in the

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Requirements

The recommended dietary allowances for Calcium, as suggested by the ICMR is given below

Age Group RDA for calcium (mg/day)

Infant 0 – 12 months 500

Children 1 – 9 years 400

Children 10 – 15 years 600

Adolescent 16 – 18 years 500

Adult 400

Pregnant women 1000

Lactating women 1000

Deficiency

Calcium related health problems occur due to inadequate intake, improper absorption or utilization of calcium.

1. Osteoporosis is a condition found primarily among middle aged and elderly woman, where the bone mass of the skeleton is diminished. It is a condition of multiple origin. It results due to the following reasons: (i) Prolonged dietary inadequacy (ii) Poor absorption and utilization of calcium (iii) Immobility (iv) Decreased levels of oestrogen in post-menopausal women. (v) Hyper parathyroidism (vi) Vitamin – D deficiency 2. Osteomalacia is a condition in which the quality but not the quantity of bone is reduced. 3. Tetany occurs when Calcium in the blood drops below the critical level. There is a change in the stimulation of nerve cells resulting in increased excitability of the nerve and uncontrolled contraction of the muscle tissue. Hence Calcium and Phosphorous ratio in the diet should be maintained at 1:1 for proper utilization of Calcium in the body.

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MICROMINERALS

Micro minerals are also known as trace elements. The micro minerals are Iron, Iodine, Zinc, Copper, Fluoride, Selenium, Chromium, Manganese, cobalt and Molybdenum. However, only the deficiency of few of these elements is observed in humans. Iron and Iodine deficiencies are wide spread while deficiencies of Cu, Zn, Cr and Se have been reported in recent years.

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IRON

The total body iron is 4g in adults. Iron exists in a complex form in our body. It is present as

a) Iron porphyrin compounds – hemoglobin in RBC, myoglobin in muscle. b) Enzymes – (eg) peroxidases, succinase dehydrogenase and cytochrome oxidase. c) Transport and storage forms – (eg) transferrin and ferritin.

Functions

The chief functions of iron in the body are:

1. Iron forms a part of the protein – haemoglobin which carries oxygen to different parts of the body. 2. It forms a part of the myoglobin in muscles which makes oxygen available for muscle contraction. 3. Iron is necessary for the utilization of energy as part of the cells metabolic machinery. 4. As part of enzymes iron catalyses many important reactions in the body. Examples are a. Conversion of beta carotene to active form of Vitamin A b. Synthesis of carnitine, purines, collagen and neurotransmiters. c. Detoxification of drugs in the liver.

Food Sources

The iron present in food can be as haem and non-haem iron depending upon the source from which it is obtained. Heme iron is obtained from animal tissues, non-heme iron is obtained from plant foods. Sources of non-heme iron are ragi, green leafy vegetables, dried fruits and jaggery. Liver, fish, poultry, meat, eggs dates are good sources of heme iron. Heme iron is absorbed and utilized better than the non-heme iron. Iron absorption from Indian diets is only 3 percent as it is mainly cereal based diet.

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Requirement

Iron requirements for various age groups according to the ICMR guidelines are listed below

Age Group RDA for Iron (mg/day)

Birth – 1 year 1

1 – 5 year 15 – 20

6 – 12 years 15 – 20

13 – 18 years

 Boys 25  Girls 35

Adult

 Man 20  Woman 30

Pregnant women 40

Lactating women 30

Deficiency

Dietary iron deficiency leads to nutritional anaemia. Nutritional anaemia is defined as the condition that results from the inability of the erythropoetic tissue to maintain a normal haemoglobin concentration. Anaemia occurs when the haemoglobin level falls below 12 g/dl in adult man and woman. During pregnancy haemoglobin level below 11 g/dl is termed anaemia. Nutritional anaemia is the common form of anaemia affecting women in reproductive years, infants and children which is mainly due to poor intake and absorption. Iron deficiency anaemia is wide spread in our country, with the prevalence varying from 45% in men and 70% in women and children. The major cause of anemia in India is because of Iron and folic acid deficiency.

Nutritional anemia is manifested as:

1. Reduced Haemoglobin level (less than 12 g/dl) 2. Defects in the structure, function of the epithelial tissues 3. Paleness of skin and the inside of the lower eyelid is pale pink

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5. Finger nails becoming thin and flat and eventually (spoon shaped nails) koilonychia develops. 6. Progressive untreated anaemia results in cardiovascular and respiratory changes leading to cardiac failure. The general symptoms include lassitude, fatigue, breathlessness on exertion, palpitations, dizziness, sleeplessness, dimness of vision, and increased susceptibility to infection.

IODINE

Iodine is an essential constituent of the thyroid hormone produced by the thyroid glands. It occurs as free iodide ions or as protein bound iodine in our body. About 15 – 23 mg of iodine is present in the adult human body. The body store of iodine is predominantly present in thyroid gland and also in salivary gland, mammary glands gastric glands and in kidneys to a certain extent.

Function

Iodine is essential for the synthesis of the thyroid hormones T3 and T4.

Sources

Richest source of iodine are sea foods like sea fishes and common salt from sea water. Iodine content of vegetables, fruits and cereals depends upon the iodine content of the soil in which they grow. The soil of mountainous regions contains less iodine.

Requirement

The ICMR recommended dietary allowance for Iodine is 150 μg/day.

Deficiency

Iodine deficiency in the diet causes enlargement of the thyroid gland called as “goitre”. Goitre occurs in people staying in hilly regions where the iodine content of water and soil is comparatively less. In India goitre is common in hilly districts of Himalaya. Goitre can be treated by administration of iodine. If treatment is given in early stages goitre can be corrected. Severe iodine deficiency in children leads to hypothyroidism resulting in retarded physical and mental growth. This condition is known as cretinism. Goitrogens are substances present in foods which cause goitre. These substances react with iodine present in the food making it unavailable for absorption. Foods like cabbage, cauliflower, raddish contain goitrogens.

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ZINC

Zinc is primarily intracellular substance. Its total quantity in the body is 2.3g. Largest stores of Zinc are present in the bones. Zinc forms a constituent of the blood and is an important element performing a range of function in the body as it is a cofactor for a number of enzymes.

Functions

1. Zinc is a constituent of enzymes such as carbonic anhydrase, alkaline phosphatase, and lactic dehydrogenase. 2. It is a constituent of the hormone insulin 3. It plays a major role in the synthesis of DNA and proteins.

Sources

Meat, unprocessed cereals and legumes are good sources. Fruits and vegetables are poor sources.

Requirements

The daily requirement of Zinc in adults is 15.5 mg/day as recommended by the ICMR expert group.

Apart from iron, iodine and zinc; Copper, selenium and fluorine are also essential trace elements. Copper is an essential element in iron absorption. Selenium is an essential element along with Vitamin E for maintaining integrity of the liver cells. Fluorine is required in minimum amounts to prevent dental caries and excessive consumption leads to mottling of teeth.

Other trace nutrients known to be essential in tiny amounts include nickel, silicon, vanadium, and cobalt.

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VITAMINS

Vitamins are organic substances present in small amounts in food they are required for carrying out vital functions of the body. They are involved in the utilization of the major nutrients like proteins, fats and carbohydrates. Though needed in small amounts, they are essential for health and well-being of the body. When these Vitamins were discovered on the basis of their function and before their chemical nature were elucidated, they were designated as A, B, C, and D or in terms of their major functions like, anti-neuritic, anti-richitic Vitamins. Vitamins are classified based on their solubility as fat soluble and water soluble vitamins.

CLASSIFICATION OF VITAMINS

Vitamins

Fat soluble Water soluble

A, D, E, and K Vitamin B1, B2, B6, B12 (Niacin), Nicotinic Acid, Folic Acid and Vitamin- C

Water soluble vitamins are not accumulated in the body, but are readily excreted while fat soluble vitamins are stored in the body. For this reason excessive intake of fat soluble vitamins, especially Vitamin A and D can prove toxic. Excessive intake leads to the condition called hypervitaminosis.

FAT SOLUBLE VITAMINS

VITAMIN A

Vitamin A was the first fat soluble vitamin to be recognized. Three forms of Vitamin A are active in the body, retinol, retinal and retinoic acid. They are collectively called as retinoids. Beta carotene is the provitamin of Vitamin A. (Provitamins are substances that are chemically related to a vitamin but must be changed by the body into the active form of the vitamin). Vitamin A in the diet comes in two forms, Retenoids (preformed Vitamin A) and carotenoids. Vitamin A is present in vegetable foods which contain yellow pigment called carotenes. It was isolated from carrots hence called carotenoids which are provitamins of Vitamin A.

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Functions

1) A well understood function of retinol is in the visual process. The retina of the human eye contains two distinct photo receptors of which one is sensitive to light intensities. Vitamin A is essential for the formation of rhodopsin and normal functioning of the retina for clear vision in dim light. Lack of Vitamin A leads to impaired adaptation to darkness. 2) Participates in protein synthesis and cell differentiation and thereby maintaining the health of the epithelial tissues and skin. 3) Supports reproduction and growth 4) Vitamin A regulates the antibodies and cellular immune response. It is essential for maintaining the epithelial tissue which is the first line of defence against invading microorganism. 5) Beta carotene acts as an antioxidant capable of protecting the body against disease like cancer, cardiovascular diseases and cataract.

Sources

Vitamin A in the human diet exists as retinol or as retinal or as beta carotene which has to be converted to Vitamin A. Foods of animal origin contain retinol. Plant sources are rich in Beta carotene. Only one third of the dietary beta Carotene is absorbed. Beta Carotene from green leafy vegetables is well utilized than from carrots and papayas. Good sources of Vitamin A are sheep liver, butter, ghee, egg, milk, curds, liver oils of shark and halibut. Good sources of beta carotene are agathi, amaranth, drumstick leaves, green leafy vegetables, mango, papaya, carrot and jack fruit.

Requirements:

The ICMR recommended dietary allowance for retinol is given below.

Age Group Retinol (μg/day)

Man 600

Woman 600

Pregnant women 600

Lactating women 950

Infants 350

Children 400-600

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Effects of Deficiency

Deficiency of Vitamin A is manifested as nutritional blindness and increased susceptibility to infection. Nutritional blindness is an important public health problem among young children in India. Night blindness is an early symptom of Vitamin A deficiency. The individual cannot see in dim light. This can be corrected with adequate supply of Vitamin A. In the absence of adequate Vitamin A intake the outer lining of the eye ball loses its usual moist, white appearance and becomes dry and wrinkled called xerosis. This condition is followed by raised muddy dry triangular patches on the conjunctiva called the bitots spots.

Redness and inflammation of the eye and gradual loss of vision may follow. The central portion of the eye loses its transparency and becomes opaque and soft if not treated and leads to total blindness termed Xeropthalmia. Xeropthalmia encompasses all ocular manifestations of Vitamin A deficiency. Increased susceptibility to infection occurs because the mucous membrane lining becomes dry and rough which is easily invaded by the micro – organism.

Hypervitaminosis

Intake of large amount of Vitamin A for prolonged periods can lead to toxic symptoms which include irritability, headache, nausea and vomitting.

VITAMIN D

Vitamin D can be synthesized in the body in adequate amounts by simple exposure to sunlight, even for 5 minutes per day is sufficient. It is essential for bone growth and calcium metabolism. It also acts as a hormone in the body by facilitating calcium absorption and deposition in the bone.

Functions

1. Vitamin D helps in the absorption of calcium and phosphorous by increasing the synthesis of calcium binding protein. 2. Vitamin D helps to maintain the calcium and phosphorous levels in the body by stimulating, a. Absorption in the gastro intestinal tract. b. Retention by the kidney 3. Vitamin D helps in deposition of calcium in the bones. The bones grow denser and stronger.

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Food Sources

The Vitamin D content of food sources from animals varies with the diet, breed and exposure to sunlight of the animal. The good sources of Vitamin D are cod liver oil, shrimp, liver, butter, yolk, cheese, milk, spinach and cabbage.

Requirements

The expert group of ICMR has not recommended dietary intake of Vitamin D for Indians. Only in those cases where the Vitamin D requirement is not met due to inadequate exposure to sunlight the ICMR recommends 400 μg/day of Vitamin D .

Deficiency

Deficiency of Vitamin D leads to decreased absorption of calcium which is manifested as muscular tetany, rickets in children and osteomalacia in adults. Due to faulty calcification of bones the following derfomities is manifested in children which is called rickets. It is a disease in which there is weakness and abnormalities in bone formation. Rickets primarily affects children.

Manifestations:

a. faulty deposition of calcium on the bones. b. Bowing of legs c. Enlargement of ends of long bones d. Deformities of ribs – beading of ribs e. Delayed closing of frontanel f. Slow erruption of teeth. g. Malformed, decay – prone teeth

Osteomalacia in Adults

Osteomalacia is a condition where the quality of the bone is reduced. It occurs in women who are not exposed to sunshine and who have depleted mineral reserves resulting from successive pregnancies and prolonged lactation. Osteomalacia is associated with low phosphorous level but low blood calcium level is the most frequent cause. The following symptoms occur

1. softening of the bones 2. deformities of the limbs, spine, thorax and pelvis 3. demineralization of the bones 4. pain in pelvis, lower back and legs 5. frequent bone fractures.

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Hypervitaminosis

As in the case of Vitamin A intake of excessive amounts of Vitamin D leads to toxic symptoms which include irritability, nausea , vomiting and constipation.

VITAMIN E

Vitamin E is known as antisterility vitamin because it is required for normal reproduction in animals and men.

Functions

1. Vitamin E is the primary antioxidant in the body and serves to protect polyunsaturated fatty acids (PUFA) from oxidation in cells and maintain integrity of the cell membrane. It also prevents the oxidation of beta carotene and Vitamin A. Vitamin E helps to maintain cell membrane integrity and protect RBC against hemolysis. 2. Vitamin E reduces platelet aggregation 3. Vitamin E is essential for the iron metabolism and the maintenance of nervous tissues and immune function. 4. Vitamin E is been promoted as an anti-aging vitamin, because as cells age they accumulate lipid breakdown products. Vitamin E prevents this accumulation in maintaining cell health.

Food Sources

Vitamin E is widely distributed in foods. It is present in high concentration in vegetable oils and in cereal grains. Wheat gum, sunflower seeds, almonds, safflower oil, eggs, butter are good sources. Meat, fruits and vegetables contain small amounts. Sesame oil and mustard oil are good sources of Vitamin E.

Requirement

The requirement of Vitamin E is linked to that of essential fatty acids (linoleic and linolenic acids). The requirement of Vitamin E is 0.8 mg/g of essential fatty acid.

Deficiency

1. Prolonged intake of Vitamin E deficient diets produces uncoordinated movement, weakness and sensory disturbances. 2. It causes haemolytic anaemia in low birth weight infants 3. Defective functioning of the retina leading to permanent blindness in premature infants occurs.

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4. It leads to reproductive failure in humans 5. Vitamin E deficiency is associated with decreased ability of the lymphocytes.

VITAMIN K:

Vitamin K is recognized as the anti-hemorrhagic factor owing to its vital role in blood clotting mechanism.

Functions

Synthesis of blood clotting proteins: Vitamin K is essential for the activation of prothrombin. This gets converted to thrombin, which in turn activates fibrinogen to form fibrin. The process of blood clotting occurs as follows:

 Injured tissue releases thromboplastin, which catalyses prothrombin formation.  Vitamin K catalyses, conversion of prothrombin to thrombin.  This in turn causes conversion of fibrinogen to fibrin which forms the clot.

Food Sources:

Dark green leafy vegetables are good sources of vitamin K. Fruits, tubers, seeds, dairy and meat products contain Vitamin K.

Requirements

The ICMR committee considered that no recommendation is needed for this Vitamin, as the synthesis of Vitamin K occurs in the lower intestine by the colonic bacteria and present widely in foods.

Effects of Deficiency

Primary deficiency arises in infants resulting in delayed blood clotting and hemorrhage. This is because the new born babies have a sterile intestinal tract thus lack in the colonic bacterial colonies which produces Vitamin K. Vitamin K deficiency does not occur in adults.

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WATER SOLUBLE VITAMINS

VITAMIN C (ASCORBIC ACID)

The chemical name for Vitamin C is ascorbic acid. It was discovered in 1747 by the British physician Lind and demonstrated that citrus fruit juices prevented and cured scurvy.

Functions

1. Ascorbic Acid is essential for formation of cement substances and collagen which is found in blood vessels teeth and bones. 2. It helps in the biosynthesis of non-essential amino acids (eg) hydroxy proline, tyrosin. 3. It is required for absorption of iron as it reduces ferric to ferrous form which is easily absorbed. 4. Vitamin C is essential for the formation of collagen a major structural protein of connective tissues. 5. It is required for normal wound healing because it helps in the formation of connective tissue. 6. Vitamin C is required for carnitine synthesis which aids in the transport of fatty acids in the cell. 7. Vitamin C is essential for the synthesis of norepinephrine a neurotransmitter. 8. It activates hormones (eg) growth hormone, gastrin releasing peptide, calcitonin, gastrin oxytocin. 9. Drug detoxifying metabolic systems in the body require Vitamin C for its optimal activity. 10. Vitamin C is an excellent anti-oxidant. It combines with free radicals oxidizing them to harmless substances that can be excreted.

Food Sources

Amla, drumstick leaves, guava, cashew fruit, agathi, cabbage, bitter gourd, oranges, and tomatoes are good sources of ascorbic acid. Cereals and pulses are poor sources. Vitamin C content of pulses increases on germination.

Requirements

The recommended dietary allowance of ICMR for ascorbic acid is as given below.

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Age Group Requirement (mg/day)

Adult 40

Pregnant women 40

Lactation 80

Infants 25

Children 40

Effects of Deficiency

Prolonged deficiency of ascorbic acid produces a disease condition called as ‘ scurvy’ in both infants and adults.

Infantile scurvy:

There is loss of appetite, failure to gain weight, irritability, palor, defective growth of bones. Haemorrhage occurs under the skin. There is defective formation of teeth and gums are swollen. The ends of the ribs become prominent resulting in beaded appearance called scorbutic rosary.

Adult Scurvy:

1. General manifestation are fever, susceptibility to infection, and delayed wound healing. 2. Anaemia: Microcytic hypochromic anaemia develops due to failure of absorption of iron. 3. Gums become spongy and bleed easily. Gums become swollen and ulcerated. 4. The blood vessels become fragile and porous due to defective formation of collagen. Joints become swollen and tender. 5. Clinical symptoms appear when total body pool of ascorbic acid decreases. Skin becomes rough and dry. There are small petechial hemorrhages around hair follicles.

THIAMINE

Thiamine is known as Vitamin B1. Deficiency of thiamine leads to beri – beri. This condition is widely prevalent among population whose diet contains more of polished cereals.

Functions

1. Thiamine is converted to thiamine pyrophosphate (TPP), which is an important co enzyme in the carbohydrate metabolism. 2. It is involved in transmission of nerve impulses across the cells

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3. Thiamine as TPP is an essential cofactor for the conversion of amino acid tryptophan to niacin.

Sources

Yeast, whole wheat, millets, hand pounded rice, parboiled rice are good sources of thiamine. The bran contains most of the thiamine in the cereals. Gingelly seeds, groundnut, soya bean, cashew nuts, organ meats, pork, liver and eggs supply thiamine.

Requirements

Thiamine is involved in the carbohydrate metabolism. Its requirement is related to energy derived from carbohydrate. The ICMR expert group recommends an allowance of 0.5 mg per 1000 Kcal for adults and for infants 0.3 mg/1000 Kcal is suggested. The recommended dietary allowance per day is given below.

Age Group Requirement (mg/day)

Man

 Sedentary 1.2  Moderate 1.4

 Heavy work 1.6

Woman

 Sedentary 0.9  Moderate 1.1

 Heavy work 1.2

Pregnant woman +0.3

Lactation + 0.3 – + 0.2

Infants 55 mg/kg – 50 mg/kg

Children (1 – 9 years) 0.6 – 1.2

Boys (10 – 18 years) 1.1 – 1.3

Girls (10 – 18 years) 1.0

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Effects of Deficiency

Deficiency of thiamine is associated with low calorie intake. Severe deficiency of thiamine produces a disease known as beri – beri. It is manifested as a. Dry beri – beri: There is loss of appetite, tingling numbness and burning sensation in hands and feet. Calf muscles are tender. Knee and ankle jerks are sluggish. In later stages complete loss of sensation in hands and legs occur. It is characterized by foot and waist drop. Mental depression and confusion occurs. b. Wet beri – beri: In this case there is enlargement of heart and the cardiac output is high. Oedema or accumulation of fluid in legs, face and trunk is observed. palpitations are marked. c. Infantile beri – beri: It occurs in first few months of life if the diet of the mother is deficient in thiamine. Symptoms are restlessness, sleeplessness, constipation, enlargement of the heart and breathlessness.

RIBOFLAVIN

Riboflavin or Vitamin B2 is the yellow enzyme which is heat stable unlike other B Vitamins. Riboflavin in the combined with proteins form flavo-proteins or yellow enzymes. These enzymes are of two types, those containing FAD (Flavin di-nucleotide) and FMN (Flavin mono-nucleotide). These substances act as coenzymes in many biological reactions primarily in oxidation – reduction, and dehydrogenation reaction

i) Release of energy from glucose, fatty acids and amino acids. ii) Conversion of vitamin B6 and folate to active coenzymes.

They are also essential for the formation of red blood cells and also required for the synthesis of glycogen.

Food Sources

Rich sources are liver, dried yeast, egg, milk , meat, fish, whole cereals, legumes, and green leafy vegetables.

Requirements

Riboflavin requirement is related to energy intake – 0.6 mg/1000Kcal. The ICMR recommends the following requirement per day as given below.

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Age Group Requirement (mg/day)

Man

 Sedentary 1.4  Moderate 1.6

 Heavy work 1.9

Woman

 Sedentary 1.1  Moderate 1.3

 Heavy work 1.5

Pregnant woman +0.2

Lactation + 0.3

Infants 65 mg/kg – 60 mg/kg

Children (1 – 9 years) 0.7 – 1.2

Boys (10 – 18 years) 1.3 – 1.6

Girls (10 – 18 years) 1.2

Effects of Deficiency

Riboflavin deficiency is prevalent mainly among the low income groups particularly the vulnerable group and the elderly adults. Riboflavin deficiency is characterized by

1. Soreness and burning of the mouth and tongue. 2. Lesions at the angles of the mouth called Angular Stomatitis. 3. The inflammation of the tongue called glossitis 4. Dry chapped appearance of the lip with ulcers termed cheilosis. 5. The skin becomes dry and results in seborehoeic dermatitis. 6. Photophobia, lacrimation, burning sensation of the eyes and visual fatigue. 7. Decreased motor co-ordination 8. Normocytic anaemia

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NIACIN

Niacin or Nicotinamide (amide form) is required by all the cells of our body. Like thiamine and riboflavin it plays a vital role in the release of energy from carbohydrates, protein, fat and alcohol.

Functions

1. Nicotinamide is essential for tissue metabolism. The active forms of nicotinanide are NAD – Nicotinamide adenine dinucleotide and NADP - Nicotinamide adenine dinucleotide phosphate. 2. NAD and NADP are involved as coenzymes in large number of reversible oxidation reduction reactions. 3. Nicotinic acid enhances stomach secretion 4. NAD is involved in catabolic reactions and NADP is involved in anabolic reaction in our body.

Food Sources

Dried yeast, liver, rice polishing, peanut, whole cereals, legumes, meat, and fish are good sources. Tryptophan present in dietary protein is converted to niacin in humans. 60 mg of tryptophan yields 1 mg of niacin.

Requirements:

ICMR recommended dietary allowance of Niacin per day is given below.

Age Group Requirement (mg/day)

Man 16 – 21

Woman 12 – 16

Pregnant woman +2

Lactation +4

Infants 710 mg/kg – 650 mg/kg

Children (1 – 9 years) 8 – 13

Boys (10 – 18 years) 15 – 17

Girls (10 – 18 years) 13 – 14

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Effects of Deficiency

Deficiency of nicotinic acid causes a disease known as pellagra. It is characterized by three D's; Dermatitis, Diarrhoea and Dementia.

1. Dermatitis – Name pellagra comes from pelle-skin and agra-rough. Marked changes occur in the skin especially in the skin exposed to sun and friction areas like elbows, surfaces of arms, knees. Lesions are symmetrically distributed, in the affected parts. At first there is reddening, thickening and pigmentation of the skin. Later on there is exfoliation leading to ultimately parchment of skin – butterfly like appearance. 2. Diarrhoea – Diarrhoea enhances the deficiency state. There are structural and absorptive defects in the small intestine. Tongue appears raw, and mucous membrane of the tongue is inflammed. 3. Dementia – There is irritability, depression, poor concentration and loss of memory. Delirium is a common mental disturbance.

FOLIC ACID

Folic acid was first extracted from dark green leafy vegetables. It forms yellow crystals and is a conjugated substance made up of three acids namely pteroic, para amino benzoic acid and glutamic acid.

Functions

Folic acid coenzyme is essential in bringing about transferring single carbon units for many interconversions. A number of key compounds are formed by these reactions like

(i) Purines which are essential constituents of living cells. (ii) Thymine – this essential compound forms a key part of DNA. (iii) the formation of haem group of haemoglobin. (iv) The conversion of phenylalanine into tyrosin.

Food Sources

Green leafy vegetables, liver, kidney, gingelly seeds, and cluster beans are rich sources of folic acid.

Requirements

The recommended dietary allowances of Folic acid by ICMR are given below.

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Age Group Requirement (mg/day)

Man 100

Woman 100

Pregnant woman 400

Lactation 150

Infants 25

Children (1 – 9 years) 30 – 60

Boys and girls (10 – 70 – 100 18 years)

Deficiency

1. Simple folate deficiency results in the bone marrow producing immature cells (megaloblasts cells) and few matured red blood cells. This result in reduced oxygen-carrying capacity causing anaemia termed - Megaloblastic anaemia. 2. Folate deficiency during pregnancy causes neural tube disorders of the foetus. 3. Folate deficiency impairs the ability of the immune system to fight infection.

PYRIDOXINE (B6)

Pyridoxine is unique among the B complex Vitamins in that it functions primarily in protein metabolism. Pyridoxine denotes related substances such as Pyridoxine, Pyridoxal and Pyridoxamine are three forms in which it is present in our body.

Functions

Vitamin B6 in the form of pyridoxal phosphate functions as a co-enzyme in many biological reactions

1. Pyridoxine is essential for the process of a. Transamination: transfer of amino group from one amino acid to another. b. Deamination: Removal of the amino group c. Decarboxylation: Removal of the carboxyl group 2. Vitamin B6 is involved in several biochemical steps for the conversion of the amino acid tryptophan to niacin

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3. It aids in the formation of elastin, synthesis of messenger RNA and heme part of haemoglobin. 4. It aids in the conversion of linoleic acid to arachidonic acid. 5. In the carbohydrate metabolism it aids in the release of glycogen from liver and muscle.

Food sources

Meat, pulses and wheat are rich sources. Other Cereals are fair sources of this vitamin. Fruits and vegetables are poor sources. Cooking and processing of food causes loss of this vitamin.

Requirement

The ICMR recommended dietary allowance for pyridoxine is given in the following table.

Age Group Requirement (mg/day)

Adults 2.0

Pregnant woman 2.5

Lactation 2.5

Infants 0.1 – 0.4

Children (1 – 9 years) 0.9 – 1.6

Boys and girls (10 – 1.6 – 2.0 18 years)

Deficiency

Vitamin B6 deficiency leads to abnormalities in protein metabolism which is manifested as poor growth, convulsions, anaemia, decreased antibody formation and skin lesions. Severe deficiency leads to microcytic hypochromic anaemia. Symptoms such as weakness, nervousness, irritability, insomnia and difficulty in walking are predominant.

VITAMIN B12 (CYANOCOBALAMIN)

Until 1926, pernicious anaemia was a fatal disease of unknown origin with an unknown cure. In 1926 Minot and Murphy found that pernicious anaemia could be cured by feeding a patient at least 0.3 kg of raw liver per day. Also in 1926 Castle noted that patients with pernicious anaemia had a low level of gastric secretion. He suggested that the anti-pernicious anaemia factor had two components; an ‘extrinsic factor’ found in food and an ‘intrinsic factor’ found within normal gastric secretions. The extrinsic factor is now known as Vitamin B12 (Cobalamine).

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Functions

Vitamin B12 is necessary for normal growth and maintenance of healthy nervous tissue and normal blood formation. Vitamin B12 is involved in DNA synthesis and thus in cell replication. In the bone marrow the Vitamin B12 co-enzymes are essential for the formation of red blood cells. It facilitates the formation of folate co-enzymes needed for nucleic acid synthesis. Vitamin B12 is also required for the synthesis of myelin sheath that surrounds the nerve fibre.

Food sources

Vitamin B12 is present only in foods of animal origin. Liver sheep, shrimp, mutton, egg, and milk are good sources of Vitamin B12.Vitamin B12 are also synthesized by the colonic bacteria.

Requirements

The recommended dietary allowance prescribed by ICMR for B12 is given in the following table.

Age Group Requirement (mg/day)

Man 1.0

Woman 1.0

Pregnant woman 1.0

Lactation 1.5

Infants 0.2

Children 0.2 – 1.0

Deficiency

Pernicious anaemia is the major problem arising from an inadequate amount of vitamin B12. Pernicious anaemia is a condition characterized by very large, immature red blood cells with normal amounts of haemoglobin.

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FOOD PIGMENTS AND FLAVORING AGENTS

PLANT PIGMENTS

Chlorophyll: Chlorophyll is the green pigment of leafy vegetables and other green coloured vegetables

Carotenoids: Carotenoids are the yellow, orange, red fat soluble pigments distributed in nature. They are divided into three groups viz. carotenes present in carrot, green leafy vegetables and other fruits, lycopenes present in tomatoes and xanthophylls present in yellow fruits.

Pigments that contain the phenolic group include anthocyanin, anthoxanthin, leucoanthoxanthin, catechin, quinones and betalins. The first four groups are collectively known as “Flavanoids”.

Anthocyanin: They are a group of reddish water-soluble pigments occurring in many fruits and vegetables. Cherries, red apples, pomegranates have their colour appeal due to anthocyanins.

Anthoxanthins: They are colourless white to yellow pigments that give colour to cauliflower, onions, spinach or other leafy vegetables. In green leafy vegetables the colour is masked by chlorophyll.

Leucoanthoxanthins: They are colourless and contribute to the puckeriness or astringency of some foods, such as apple and olives. They also play an important role in the enzymatic browning of fruits.

Catechins: They are pigments that are involved in enzymatic browning.

Betalins: They are the red water soluble pigments found in beetroot and berries.

Quinone: The yellow pigment juglone is a quinone present in walnut.

Mangiferin: This is the yellow pigment belonging to the xanthone group. It is found in mangoes.

Tannins: They are complex mixtures of polymeric polyphenols. The appearance of tannins ranges from colourless to yellow or brown. Tannins contribute to the astringency of foods and also to enzymatic browning.

FLAVOUR COMPOUNDS

The flavour of fruits and vegetables are extremely important to their acceptance in the diet. The overall flavour impression is the result of the tastes perceived by the taste buds in the mouth and the aromatic compounds detected by the epithelium in the olfactory organ in the nose. In fruits and vegetables, this means that sugars, acids, salts and bitter quinine-like compounds are tasted while the

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All fruits and vegetables contain a small amount of salt, which is detected in the overall taste impressions contributing to flavour. The natural flavours of vegetables are due to mixtures of aldehydes, alcohol, ketones, organic acids and sulphur compounds. Some fruits and vegetables have an astringent taste attributed to phenolic compounds or tannins. Two types of vegetables viz., vegetables belonging to the Allium and Cruciferae families have strong flavours resulting from the presence of various sulphur containing compounds.

Allium is the genus that includes onions and garlic. Members of the family cruciferae, which include broccoli, cabbage, turnips and cauliflower, also contain prominent sulphur compounds. They are described as strong flavoured vegetables. Vegetables of the onion family are usually strong flavoured in the raw state and tend to lose some of the strong flavours when cooked in water.

Onions contain sulphur compounds that are acted upon by enzymes in the tissues when the vegetable is peeled or cut to eventually produce the volatile sulphur compounds that irritate the eyes and give biting and burning sensations on the tongue.

Vegetables of the cabbage family (cauliflower, cabbage, knolkhol) are relatively mild when raw but develop strong flavours when overcooked or improperly cooked. An amino acid s-methyl l-cysteine sulphoxide is also present in raw cabbage and appears to be a precursor of cooked cabbage flavour.

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UNIT V

NUTRITION AT VARIOUS STAGES OF GROWTH AND DEVELOPMENT

Health and nutrition are the most important contributory factors for human resource development in the country. India has been classified by the World Bank as a country with a lower middle income, with per capita GNP of US $ 996 – 3945. It ranks 160th in terms of human development among 209 countries. Among the Indian population, about 28% in the rural and 26% in the urban areas are estimated to be below the poverty line2, which is defined as the expenditure needed to obtain, on an average, 2400 Kcal per capita per day in the rural areas and 2100 Kcal in urban areas. Long-term malnutrition leads to stunting and wasting, non-communicable chronic diet related disorders, increased morbidity and mortality and reduced physical work output. It is a great economic loss to the country and undermines development.

Protein Energy Malnutrition (PEM), micronutrient deficiencies such as vitamin A deficiency (VAD), Iron Deficiency Anaemia (IDA), Iodine Deficiency Disorders (IDD) and Vitamin B- complex deficiencies are the nutrition problems frequently encountered, particularly among the rural poor and urban slum communities.

Undernutrition starts as early as during conception. Because of extensive maternal undernutrition (underweight, poor weight gain during pregnancy, nutritional anaemia and vitamin deficiencies), about 22% of the infants are born with low birth-weight (< 2500g), as compared to less than 10% in the developed countries. Both clinical and sub-clinical under-nutrition are widely prevalent even during early childhood and adolescence. Though the prevalence of florid forms of severe PEM like kwashiorkor and marasmus among preschool children is < 1%, national surveys indicate that about half of (48%) < 5 year children suffer from subclinical undernutrition such as underweight (43%) stunting and wasting (20%) which indicates that undernutrition is of long duration. The studies have shown that there is a steep increase in the prevalence of underweight with increase of age, from 27% at 6 months of age to a high of 45% at 24 months of age. This is attributable to faulty infant and young child feeding practices prevailing in the community.

Persistent undernutrition throughout the growing phase of childhood leads to short stature in adults. About 33% of adult men and 36% of the women have a Body Mass Index (BMI) [Weight in kg/ (Height in meter)] below 18.5, which indicates Chronic Energy Deficiency or CED. In the case of vitamin A deficiency, 0.8-1% of preschool children shows the signs of Bitot's spots and night blindness. Vitamin A deficiency also increases the risk of disease and death.

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Among children between the ages of 6 and 59 months, a majority (70%) are anemic. Nearly three fourth (75%) of women in India are anemic, with the prevalence of moderate to severe anemia being highest (50%) among pregnant women. It is estimated that nutritional anemia contributes to about 24% of maternal deaths every year and is one of the important causes of low birth weight. It adversely affects work output among adults and learning ability in children.

Iodine deficiency disorders (IDD) are very common among large sections of population in several parts of the country. About 167 million are estimated to be living in IDD endemic areas. Iodine deficiency causes goitre (enlargement of thyroid gland in the neck), neonatal hypothyroidism, cretinism among new born, mental retardation, delayed motor development, stunting, deaf-mutism and neuromuscular disorders. The most important consequence of iodine deficiency in mothers is cretinism in which the children suffer from mental and growth retardation right from the birth. About 90,000 still-births and neonatal deaths occur every year due to maternal iodine deficiency. Around 54 million persons are estimated to have goitre, 2.2 million have cretinism and 6.6 million suffer from mild psycho-motor handicaps.

India is passing through the phase of economic transition and while the problem of undernutrition continues to be a major problem, prevalence of over-nutrition is emerging as a significant problem, especially in the urban areas. The prevalence of overweight/obesity is higher among the women (10.9%) compared to men (7.8%) in rural areas. The prevalence of Diabetes Mellitus and Coronary Heart Disease (CHD) is also higher in urban areas as compared to their rural counterparts. The incidence rate of cancer is comparatively higher among women (123) compared to men (113 for 100,000).

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DIET FOR INFANTS

Feed home based semi-solid foods to the infant after six months because easy to cook home-made preparations are hygenic and healthy foods for the growing baby.

 Breast-milk alone is not adequate for the infant beyond 6 months of age.  Introduction of food supplements (semi-solid complementary foods) along with breast- feeding is necessary for infants after 6 months of age.  Provision of adequate and appropriate supplements to young children prevents malnutrition.  Hygienic practices should be observed while preparing and feeding the complementary food to the child; otherwise, it will lead to diarrhoea.

It is well accepted that breast milk is the best food for an infant. Fortunately, in India, most rural mothers are able to breast-feed their children for prolonged periods. In fact, this is a boon to Indian children as otherwise the prevalence of under-nutrition among them would have been much higher. However, often, children are solely breast-fed even beyond the age of one year in the belief that breast-milk alone is adequate for the child until he/she is able to pick up food and eat. This practice results in under-nutrition among young children. Working mothers, on the other hand are unable to breast-feed their children for longer periods, as they go to work outside.

Foods that are regularly fed to the infant, in addition to breast-milk, providing sufficient nutrients are known as supplementary or complementary foods. These could be liquids like milk or semi- solids like 'kheer' in the case of infants or solid preparations like rice etc., in the case of children over the age of one year. At birth, mother's milk alone is adequate for the infant. Requirements of all the nutrients progressively increase with the infant's growth. Simultaneously, the breastmilk secretion in the mother comes down with time. Thus, infants are deprived of adequate nutrients due to the dual factors of increased nutrient requirements and decreased availability of breast-milk. Usually, these changes occur at about 6 months of age. Hence, promotion of optimal growth in infants, calls for introduction of adequate food supplements in addition to continued breast feeding, from the age of

6 months onwards.

Can home-made recipes be nutritious supplements?

Low-cost food supplements can be prepared at home from commonly used ingredients such as cereals (wheat, rice, ragi, jowar, bajra, etc.); pulses (grams/dhals), nuts and oilseeds (groundnut, sesame, etc.), oils (groundnut oil, sesame oil etc.) and sugar and jaggery. Such supplements are

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What are the principles in preparing complementary food supplements?

Weaning foods based on cereal-pulse-nut and sugar/ jaggery combinations will provide good quality protein, adequate calories and other protective nutrients. Since infants cannot consume bulky complementary food, in sufficient quantities, energy-rich foods like fats and sugars should be included in such preparations.

Infants can also be fed green leafy vegetables (GLVs), which are rich, yet inexpensive, sources of vitamins and minerals. However, greens should be well cleaned before cooking lest the infants develop loose motions. Dietary fibre in green leafy vegetables can, by itself, promote the bowel movements leading to loose motions in infants. Since GLVs are rich in dietary fibre, it is advisable to initially feed only the juice of the GLVs after cooking them properly.

Infants should be introduced to different vegetables and fruits gradually. It should, however, be remembered that these dietary articles should be thoroughly cooked and mashed before feeding. In families which can afford egg yolk and meat soup can be introduced. At about one year of age, the child should share the family diet.

Amylase-Rich Foods (ARFs)

Flours of germinated cereals, which are rich in the enzyme alpha-amylase, constitute ARFs. Even small amounts of this type of foods liquefy and reduce the bulk of the cereal-based diet. Thus, ARFs help in increasing the energy density of weaning gruels and in reducing its bulk as well. Mothers can add ARF to increase the digestibility of the low-cost weaning foods prepared at home. Preparation of ARF is very simple and can be done by mothers at home.

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How to feed a young infant?

Infants cannot eat large quantities of food in one sitting at a given time. So, they should be fed small quantities at frequent intervals (3-4 times a day). Also, the food should be of semi-solid consistency for easy swallowing. When such semi-solid foods are offered initially, the infant tends to spit it out. This should not be mistaken as dislike for that food. The fact is that the young infant cannot achieve full coordination needed for the act of swallowing and hence, brings out the food by movements of its tongue. Physiological maturity of swallowing the semi-solid food develops when the food is regularly given every day.

What are the hygienic practices to be adopted?

It is important to ensure that hygienic practices are scrupulously followed. All the dietary ingredients should be thoroughly cleaned. Vegetables should be washed well to remove contaminants/ parasites/ pesticides before cutting. Vegetables should preferably be steam-cooked to reduce cooking losses. At the time of preparation and feeding of the recipes, mother should observe proper personal hygiene and the utensils used for cooking should be thoroughly washed or sterilized, wherever possible. A number of pre-cooked and ready-to-eat foods can be prepared for use as complementary foods. Such foods should be stored in clean bottles or tins. As feeding is likely to be time consuming, the cup or the plate from which the recipe is being fed to the infant should be kept covered to protect it from flies. Most often, diarrhoea is caused by unhygienic practices adopted by

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SBS, EDC Human Nutrition study material 2016-17 mothers. The weaning foods which are properly cleaned and well-cooked are safe even for young infants.

What should be done if breast-milk is not adequate?

 If breast-feeding fails, the infant needs to be fed animal milk or commercial infant formula.  Milk should be boiled before being fed to the baby.  To start with, milk may be diluted with an equal volume of water.  Full strength milk may be started from 4 weeks of age.  Infants fed animal milk should receive supplements of iron and vitamin C.  About 120-180 ml of milk should be fed with one teaspoon of sugar per feed, 6-8 times over the day.  While reconstituting the infant formula, the instructions given on the label should be strictly followed.  The feeds should be prepared and given using a sterile cup, spoon, bottles and nipples taking utmost care.  Overfeeding should be avoided in artificially-fed infants to prevent obesity.  Low-cost home-made complementary foods should be preferred.

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DIET FOR CHILDREN AND ADOLESCENTS

Ensure adequate and appropriate diets for children and adolescents both in health and sickness

Rationale: Well-formulated balanced diets for children and adolescents help in their optimum growth and boosts their immunity

 A nutritionally adequate and balanced diet is essential for optimal growth and development.  Appropriate diet and physical activity during childhood is essential for optimum body composition, BMI and to reduce the risk of diet-related chronic diseases in later life and prevent vitamin deficiency.  Common infections and malnutrition contribute significantly to child morbidity and mortality.  A child needs to eat more during and after episodes of infections to maintain good nutritional status.

Why do children and adolescents require more food?

Childhood and adolescence are periods of continuous growth and development. An infant grows rapidly, doubling its birth weight by 5 months and tripling it by 1 year of age. During the second year, the child increases not only in height by 7-8 cm but also gains 4 times of its birth weight. During the pre-adolescent period the child grows, on an average, 6-7 cm in height and 1.5 to 3 kg in weight every year and simultaneously development and maturation of various tissues and organs take place.

Adolescent period (teenage) is spread almost over a decade. It is characterized by rapid increase in height and weight, hormonal changes, sexual maturation and wide swings in emotion. Adolescent growth spurt starts at about 10-12 years in girls and two years later in boys. The annual peak rates for height and weight are 9-10 cm and 8-10 kg. Development of critical bone mass is essential during this period as this forms the ground for maintaining mineral integrity of the bone in later life. The pattern and proportion of various body components like body water, muscle mass, bone and fat increase during the entire childhood and adolescence to reach adult values by about 18 years. Adolescent girls are at greater physiological stress than boys because of menstruation. Their nutritional needs are of particular importance as they have to prepare for motherhood. All these rapid anabolic changes require more nutrients per unit body weight.

Growing children and adolescents require more calcium. Though recommended dietary allowances for calcium are about 600-800 mg/day, it is desirable to give higher quantities of calcium

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SBS, EDC Human Nutrition study material 2016-17 for adolescents to achieve high peak bone mass. To achieve optimal peak bone mass, it is recommended to consume calcium rich foods like milk and milk products, fox tail millet (Ragi), til etc.

Young children below the age of 5 years should be given less bulky foods, rich in energy and protein such as legumes, pulses, nuts, edible oil/ghee, sugar, milk and eggs. Vegetables including green leafy vegetables and locally available seasonal fruits should be part of their daily menu. Snacks make a useful contribution to the nutrient requirements, particularly in older children and adolescents. Frequent changes in the menu are often liked by children.

Older children and adolescents should consume plenty of milk to fulfil the high calcium requirements. Cooking oils/ghee (25-50g) should be consumed. Overindulgence in fats may be avoided. Excessive salt intake should be avoided particularly by children having a family history of hypertension. Adolescence is the vulnerable stage for developing wrong food habits as well as bad habits like smoking, chewing tobacco or drinking alcohol. These should be avoided. In addition to consumption of a nutritious well balanced diet, appropriate lifestyle practices and involvement in physical activity such as games/sports should be encouraged among children and adolescents.

How do infections in children lead to malnutrition?

Common childhood infections like diarrhoea, measles and pneumonia occur in association with malnutrition and contribute to about 70% of mortality. Appropriate feeding during infection is essential, which demands a lot of patience from the mother. During periods of infection, children tend to eat less due to reduced appetite. Many children vomit frequently. Nutrients are also lost in urine and faeces. The unhealthy practice of restricting diet, including breast-feeding, by the mother during any sickness could further aggravate the problem. Hence, extra care is needed in feeding the child appropriately during and after illness to prevent subsequent nutritional deficiencies.

How should a child be fed during illness?

Breast-feeds are often well accepted and tolerated even by sick children and should be continued except in severe gastroenteritis associated with shock. For older children, consuming an adult diet, soft cooked food may be offered at frequent intervals. The quantity of the feeds may be increased, after the illness has subsided, till the original weight is regained.

What should be done during diarrhoea?

Diarrhoea is a common childhood disease which leads to dehydration and sometimes death. The child requires prompt correction of fluid and electrolyte loss using oral rehydration solution

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(ORS) along with appropriate/adequate feeding. ORS can be prepared by adding a pinch of salt (between thumb and index finger) and a teaspoon of sugar to a glass of potable water. Home-made fluids such as rice kanji or buttermilk with salt can also be used. During infections, children should frequently be given small quantities of fluids by mouth, including plain water.

During diarrhoea, feeding should be continued, though this goes against the popular practice. Breast-milk promotes sodium and water transport across the gut and, thus, prevents dehydration and weight loss, in addition to providing other nutrients. The diet of 1-2 year old children with diarrhoea should provide energy of about 1000 Kcal/day. Calorie-rich, semi-solid, soft diets may be prepared from a variety of cereals and pulses. Sprouted grains are easily digestible and provide good nutrition. Fat and sugar help in reducing the bulk of the diets and make them energy dense.

Milk may be mixed with cereal diet to avoid lactose malabsorption. If milk is not tolerated, it may be replaced by an equal volume of curd/yogurt/soymilk. Mashed vegetables may be incorporated in the diet. Feeding becomes easier after the infection subsides. About 6-8 feeds should be given during the day so that the extra food (120-140 Kcal/kg) may be consumed by the child without any difficulty.

How important is the problem of lactose intolerance?

Deficiency of the enzyme lactase leads to lactose intolerance. During acute or chronic diarrhoea, lactose intolerance is a mild and transient problem. This problem can be overcome by reducing the quantity of milk taken at a time or taking milk along with a cereal-pulse meal. There is no need to stop milk in acute diarrhoea. In chronic diarrhoea, some children may develop lactose intolerance. In such children, milk may be stopped temporarily. A diet based on cereals and pulses or chicken and egg white allows the gut to recover and milk can then be slowly introduced. Adequate feeding, during and after, diarrhoea prevents malnutrition.

Eat Calcium-Rich Foods

 Calcium is needed for growth and bone development.  Children require more calcium.  Calcium prevents osteoporosis (thinning of bones).  Milk, curds and nuts are rich sources of bio-available calcium (Ragi and GLV are also good dietary sources of calcium).  Regular exercise reduces calcium loss from bones.  Exposure to sunlight maintains vitamin D status which helps in calcium absorption.

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During Illness

 Never starve the child.  Feed energy-rich cereals-pulse diet with milk and mashed vegetables.  Feed small quantities at frequent intervals.  Continue breast-feeding as long as possible.  Give plenty of fluids during illness.  Use oral rehydration solution to prevent and correct dehydration during diarrhoea episodes.

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DIET FOR PREGNANT AND LACTATING WOMEN

Ensure provision of extra food and healthcare to pregnant and lactating women.

Rationale: Additional food and extra care are required during pregnancy and lactation

 Pregnancy is physiologically and nutritionally a highly demanding period. Extra food is required to meet the requirements of the fetus.  A woman prepares herself to meet the nutritional demands by increasing her own body fat deposits during pregnancy.  A lactating mother requires extra food to secrete adequate quantity/ quality of milk and to safe guard her own health.

Pregnancy is a demanding physiological state. In India, it is observed that diets of women from the low socioeconomic groups are essentially similar during pre-pregnant, pregnant and lactating periods. Consequently, there is widespread maternal malnutrition leading to high prevalence of low birth weight infants and very high maternal mortality. Additional foods are required to improve weight gain in pregnancy (10-12 Kg) and birth weight of infants (about 3 Kg).

The daily diet of a woman should contain an additional 350 calories, 0.5 g of protein during first trimester and 6.9 g during second trimester and 22.7 g during third trimester of pregnancy. Some micronutrients are specially required in extra amounts during these physiological periods. Folic acid, taken throughout the pregnancy, reduces the risk of congenital malformations and increases the birth weight. The mother as well as the growing foetus needs iron to meet the high demands of erythropoiesis (RBC formation). Calcium is essential, both during pregnancy and lactation, for proper formation of bones and teeth of the offspring, for secretion of breast-milk rich in calcium and to prevent osteoporosis in the mother. Similarly, iodine intake ensures proper mental health of the growing foetus and infant. Vitamin A is required during lactation to improve child and C need to be taken by the lactating mother.

How can the pregnant and lactating women meet these nutritional demands?

The pregnant/lactating woman should eat a wide variety of foods to make sure that her own nutritional needs as well as those of her growing foetus are met. There is no particular need to modify the usual dietary pattern. However, the quantity and frequency of usage of the different foods should be increased. She can derive maximum amount of energy (about 60%) from rice, wheat and millets. Cooking oil is a concentrated source of both energy and polyunsaturated fatty acids. Good quality protein is derived from milk, fish, meat, poultry and eggs. However, a proper combination of

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SBS, EDC Human Nutrition study material 2016-17 cereals, pulses and nuts also provides adequate proteins. Mineral and vitamin requirements are met by consuming a variety of seasonal vegetables particularly green leafy vegetables, milk and fresh fruits. Bioavailability of iron can be improved by using fermented and sprouted grams and foods rich in vitamin C such as citrus fruits. Milk is the best source of biologically available calcium. Though it is possible to meet the requirements for most of the nutrients through a balanced diet, pregnant/lactating women are advised to take daily supplements of iron, folic acid, vitamin B and calcium.

What additional care is required?

Adequate intake of a nutritious diet is reflected in optimal weight gain during pregnancy (10 kg) by the expectant woman. She should choose foods rich in fibre (around 25 g/1000 kcal) like whole grain cereals, pulses and vegetables, to avoid constipation. She should take plenty of fluids including 8-12 glasses of water per day. Salt intake should not be restricted even to prevent pregnancy-induced hypertension and pre-eclampsia. Excess intake of beverages containing caffeine like coffee and tea adversely affect foetal growth and hence, should be avoided.

In addition to satisfying these dietary requisites, a pregnant woman should undergo periodic health check-up for weight gain, blood pressure, anaemia and receive tetanus toxoid immunization. She requires enough physical exercise with adequate rest for 2-3 hrs during the day. Pregnant and lactating women should not indiscriminately take any drugs without medical advice, as some of them could be harmful to the foetus/baby. Smoking and tobacco chewing and consumption of alcohol should be avoided. Wrong food beliefs and taboos should be discouraged.

The most important food safety problem is microbial food borne illness and its prevention during pregnancy is one of the important public health measures. Avoiding contaminated foods is important protective measure against food borne illness.

Eat Folate-Rich Foods

 Folic acid is essential for the synthesis of haemoglobin.  Folic acid deficiency leads to macrocytic anaemia.  Pregnant women need more of folic acid.  Folic acid supplements increase birth weight and reduce congenital anomalies.  Green leafy vegetables, legumes, nuts and liver are good sources of folic acid.  500 mg (0.5mg) folic acid supplementation is advised pre-conceptionally and through-out pregnancy for women with history of congenital anomalies (neural tube defects, cleft palate).

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Eat Iron-Rich Foods

 Iron is needed for haemoglobin synthesis, mental function and to provide immunity against diseases.  Deficiency of iron leads to anaemia.  Iron deficiency is common particularly in women of reproductive age and children.  Iron deficiency during pregnancy increases maternal mortality and low birth weight infants.  In children, it increases susceptibility to infection and impairs learning ability.  Plant foods like green leafy vegetables, legumes and dry fruits contain iron.  Iron is also obtained through meat, fish and poultry products.  Iron bio-availability is poor from plant foods but is good from animal foods.  Vitamin C - rich fruits like gooseberries (Amla), guava and citrus improve iron absorption from plant foods.  Beverages like tea bind dietary iron and make it unavailable. Hence, they should be avoided before during or soon after a meal.  Commonly consumed plant based diets provide around 18mg of iron as against recommended intake of 35 mg per day. Therefore, supplementation of iron (100 mg elemental iron, 0.5 mg folic acid) is recommended for 100 days during pregnancy from 16th week onwards to meet the demands of pregnancy.

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DIET FOR OLDER PERSONS

Include micronutrient rich foods in the diets of elderly people to enable them to be fit and active

Rationale: Senior citizens need more of vitamins and minerals to remain healthy and active

 Body composition changes with advancing age, and these changes affect nutritional needs of the elderly.  Elderly or aged people require reduced amounts of calories, as their lean muscle mass and physical activity decrease with ageing.  Elderly are more prone to diseases due to lowered food intake, physical activity and resistance to infection.  Good /healthy food habits and regular comfortable level of physical activity are required to minimise the ill effects of ageing and to improve the quality of life.  Elderly need adequate amounts of protein, carbohydrates, fat, vitamins, minerals and dietary fibre.  Elderly need more calcium, iron, zinc, vitamin A and antioxidants to prevent age-related degenerative diseases and for healthy ageing.

Who is an elderly person?

According to WHO, individuals of 60 years and above constitute the elderly. In India, the elderly constitute about 7 percent of the total population (Census, 2001) and by 2016 and by they are likely to increase to 10 percent.

How are the elderly different?

Ageing affects almost all the systems of the body, and is associated with several physiological, metabolic and psychological changes. The changes include decline in physical activity, digestion, metabolism, bone mass and muscle mass. Failing eye-sight and impaired hearing may also occur. Low appetite as a result of loss of taste and smell perception, dental problems, atrophic changes in GIT, constipation and decreased physical activity could lead to overall decrease of food intake and poor absorption of nutrients. Inability to prepare food, economic dependency and other psycho-social problems adversely affects the health and nutritional status of the elderly. There is a decline in immune function with advancing age, which leads to decreased resistance to infectious diseases. The increased parathyroid hormone (PTH) secretion in the elderly leads to increased bone turn over i.e. osteoporosis. Similarly, elderly individuals are at increased risk of osteomalacia i.e. defective bone mineralization due to lack of exposure to sunlight and poor diet.

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How can the elderly lead an active life?

In general, majority of the health problems among the elderly are nutrition related. Consumption of nutritious foods rich in micronutrients including antioxidant vitamins & minerals and fibre, comfortable level of physical activity would enable the elderly to live active and meaningful healthy lives, without being a burden on society and their family members. Uncomplicated ageing can also be quite productive, say in the domestic sphere.

What are the common diseases among the elderly?

Resistance to disease declines in the elderly. The common ailments in the elderly are degenerative diseases such as arthritis (joint diseases), osteoporosis, osteomalacia, cataract, diabetes, cardiovascular (stroke, heart diseases) problems, neurological (Parkinson's, Alzheimer's) and psychiatric (dementia, depression, delirium) disorders and cancer. Besides these, the prevalence of respiratory, gastrointestinal tract (GIT) and urinary tract infections is common among the elderly.

What type of diet should the elderly eat?

As people grow older, they tend to become physiologically less active and therefore need fewer calories to maintain their weights. The daily intake of oil should not exceed 20 g. Use of ghee, butter, vanaspati and coconut oil should be avoided. They need foods rich in protein such as pulses, toned milk, egg-white etc. The elderly population is prone to various nutritional deficiencies. Therefore, the elderly need nutrient-rich foods rich in calcium, micro-nutrients and fibre. Apart from cereals and pulses, they need daily at least 200-300 ml of milk and milk products and 400 g of vegetables and fruits to provide fibre, micro-nutrients and antioxidants. Inclusion of these items in the diet improves the quality of the diet and bowel function. Flesh foods and eggs add to the quality of diet. The diet needs to be well cooked, soft and less salty and spicy. Small quantities of food should be consumed at more frequent intervals and adequate water should be consumed to avoid dehydration, hyponatraemia and constipation.

How can elderly remain fit and active?

Exercise is an integral part of maintaining healthy life. It helps to regulate body weight. The risk of degenerative diseases is considerably decreased by regular exercise. Exercise schedule should be decided in consultation with a physician.

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Tips for good health

 Exercise regularly.  Avoid smoking, chewing of tobacco and tobacco products (Khaini, Zarda, Paan masala) and consumption of alcohol.  Check regularly for blood sugar, lipids and blood pressure after the age of 30 years at least every 6 months.  Avoid self-medication.  Adopt stress management techniques (Yoga and Meditation).

Health benefits of iodized salt

 Iodine is required for formation of thyroid hormones.  Thyroid hormones are necessary for growth and development.  Iodine deficiency leads to goitre (enlargement of thyroid gland)  Lack of iodine in the water and diet is the main cause of iodine deficiency disorders.  Iodine deficiency during pregnancy results in still births, abortions and cretinism.  Use of iodized salt ensures adequate iodine intake.

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