Caffeinated Beverage Consumption in Undergraduate Students at a Public Mid-Western University

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CAFFEINATED BEVERAGE CONSUMPTION IN UNDERGRADUATE STUDENTS AT A PUBLIC MID-WESTERN UNIVERSITY

A thesis submitted to the Kent State University College of Education, Health, and Human Services in partial fulfillment of the requirements for the degree of Masters of Science

Esha M. Parikh

May 2019

Thesis written by

Esha M. Parikh

B.S., Gujarat University, 2015

M.S., Kent State University, 2019

Approved by

______, Director, Master’s Thesis Committee Eun-Jeong (Angie) Ha

______, Member, Master’s Thesis Committee Natalie Caine-Bish

______, Member, Master’s Thesis Committee Jamie Matthews

Accepted by

______, Director, School of Health Sciences Ellen L. Glickman

______, Dean, College of Education, Health and Human Services James C. Hannon

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Parikh, Esha M., M.S., May 2019 Nutrition and Dietetics

Caffeinated beverage consumption in undergraduate students at a public mid-western university (172 pp.)

Director of Thesis: Eun-Jeong (Angie) Ha, PhD

This study is a comparative, non-experimental study with the purpose to study the pattern of consumption of caffeinated beverages in the U.S. undergraduate students

(n=233). The in-class demographic survey and three-day dietary log were collected from the students of the Science of Human Nutrition classes at a public-western university.

The caffeinated beverages and water data were collected from a dietary log for this study.

The dietary log were analyzed using ESHA software. The sugar data and the total caffeine (from all sources) was collected from the ESHA software diet analysis.

Descriptive statistics were used to analyze demographics, caffeinated beverages and caffeine content from the beverages and independent t-test were used to examine the sugar from beverages, added total sugar, caffeine from all sources and water intake in the consumers and non-consumers. The result showed that the 14% of energy in the diet was from the beverages, with coffee, soda and tea being the top three choices in the

population. 87.5% of the added total sugar in the consumers was from the caffeinated beverages suggesting the importance of the study.

ACKNOWLEDGEMENTS

First and foremost, I would like to thank my advisor, Dr. Ha, for her enormous support, guidance, encouragement, being patient and assisting me throughout whole process. I wouldn’t have been able to pass through this if it was not for her. I would also like to appreciate my committee members: Dr. Natalie Caine-Bish, Dr. Karen Lowry

Gordon and Jamie Matthews for their feedback, assistance and invaluable input to improve my research. In addition, I would like to thank Kristin Yeager for her guidance in my data analysis and giving me better understanding about statistics.

Last but not least, I would like to thank my family, especially my mom-dad, sister, my pup Mifi (for listening to me when I was frustrated), my friends; back from home and in Kent, for their support, tolerating my frustrations and being there throughout my Master’s. I am grateful for everyone who have been part of this and provided support.

TABLE OF CONTENTS

ACKNOWLEDGEMENTS ...... iv

LIST OF FIGURES ...... viii

LIST OF TABLES ...... ix

CHAPTER ...... 1

I. INTRODUCTION ...... 1 Statement of Problem ...... 3 Purpose Statement ...... 4 Hypotheses ...... 4 Operational Definitions ...... 5 II. REVIEW OF LITERATURE ...... 6 Caffeine ...... 6 Structure ...... 6 Half-life ...... 7 Absorption, Metabolism and Excretion ...... 8 Factors affecting Metabolic Rate ...... 10 Functions of Caffeine ...... 10 Sources of Caffeine ...... 12 Safe Limit for Caffeine Intake ...... 12 Caffeine Tolerance/ Withdrawal ...... 13 Caffeinated Beverages ...... 14 Tea ...... 14 Coffee ...... 19 Energy Drinks ...... 28 Sports Drink ...... 36 Soft Drinks ...... 40 Cocoa Drinks ...... 46 Caffeine and Health ...... 50

Cognitive Performance ...... 50 Sleep...... 51 Sports ...... 53 Neurodegenerative Diseases ...... 55 Bone Health ...... 57 Body Weight Management ...... 59 Heart Health ...... 60 Type 2 Diabetes Mellitus ...... 61 Liver Health ...... 62 Reproduction ...... 64 Dietary Habits of College Students ...... 65 III. METHODOLOGY ...... 68 Research Design ...... 68 Data Collection ...... 68 Procedure ...... 69 Data Analysis ...... 72 IV. JOURNAL ARTICLE ...... 73 Introduction ...... 73 Methodology ...... 75 Research Design ...... 75 Data Collection ...... 76 Procedure ...... 76 Data Analysis ...... 80 Results ...... 80 Discussion ...... 85 Characteristics of Study Population ...... 85 Top Choice of Caffeinated Beverages ...... 85 Caffeine Intake from Caffeinated Beverages ...... 89 Sugar Intake ...... 90 Water and Dehydration ...... 92 Limitation ...... 93

Conclusion ...... 94 APPENDICES ...... 95 APPENDIX A. DEMOGRAPHIC QUESTIONNAIRE...... 96 APPENDIX B. CAFFEINATED BEVERAGE INTAKE DATA SHEET ...... 101 REFERENCES ...... 103

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LIST OF FIGURES

Figure Page 1. Molecular Structure of Caffeine ...... 7

2. Caffeine Metabolism ...... 9

viii

LIST OF TABLES

Table Page

1. Caffeine content in coffee on the basis of brewing methods ...... 27

2. Caffeine content in the popular energy drinks ...... 34

3. Top 10 energy shot brands with highest amount of caffeine ...... 35

4. Caffeine content in top selling caffeinated sports drinks ...... 41

5. Top 10 best-selling soft drinks ...... 47

6. Soft drinks on the basis of caffeine content ...... 48

7. General characteristics of college students enrolled in the Science of Human Nutrition

Classes...... 81

8. Three-day average intake of caffeinated beverages (fl. oz) and caffeine (mg) from caffeinated beverages in college students (n=233) enrolled in the Science of Human

Nutrition classes ...... 82

9. Per capita fluid ounce (fl. oz) and caffeine intake (mg) over the three-day period in college students enrolled in the Science of Human Nutrition classes (n=233)...... 84

CHAPTER I

INTRODUCTION

Beverages contribute to hydration, electrolyte balance, provide antioxidants and flavonoids to body, and is a source of calcium and vitamin D. (Graham, 1992). Beverages are an important part of calories in the U.S. diet (Nielsen, Siega-Riz & Popkin, 2002) contributing to 21% of total kcal consumption (Nielsen & Popkin, 2004). Beverages include sugar-sweetened beverages, caffeinated beverages, water, milk, protein shakes, smoothies, and alcoholic drinks (“National Institute of Health”, n.d.)

Caffeinated beverages include tea, coffee, energy drinks, soft drinks, sports drink, and cocoa beverages. Coffee and tea are the most consumed caffeinated beverages by adults worldwide, and 85% of all adults are drinking at least one caffeine containing beverage daily (Frary, Johnson & Wang, 2005; Knight, Knight, Mitchell & Zepp, 2004;

Knight, Knight & Mitchell, 2006). Caffeinated beverages have caffeine as a main ingredient, along with some other compounds such as sugars and sweeteners, electrolytes, preservatives, and acids which also affects the health (“British soft drinks”, n.d.;

”Chaudhari & Roper, 2008).

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Caffeine affects human body systems including the nervous system, lipolysis process, the respiratory system, heart health, and cognitive function (Heckman, Weil &

De Mejia, 2010). Health impact varies depending on age, gender, medication, lifestyle, dietary habits, and the amount of caffeine consumed. Moderate caffeine is associated with cognitive function improvement such as increasing attention, memory, reaction time, wakefulness, and concentration (Lara, 2010). On the other hand, caffeine intake alters the natural circadian rhythms, thus affecting the sleep cycle decreasing sleep duration as well as sleep quality. High amounts of caffeine also can cause anxiety, headaches, nausea, restlessness, jitters, insomnia, heart palpitations and an increase in urinary output (Grosso, Godos, Galvano & Giovannucci, 2017). Consumption of caffeine over 400 mg/ day for adults and over 300 mg/day for children and pregnant women can be harmful causing caffeine toxicity (Morgan, Koren, & Bozzo, 2013).

Caffeinated beverages gained popularity in young population. Eighty-five percent of the college students reported consuming caffeinated beverages at least once in a day

(Mitchell, Knight, Hockenberry, Teplansky, & Hartman, 2014). For majority of them, coffee, tea and soda are the popular choices (Mahoney, Giles, Marriott, Judelson,

Glickman. Geiselman & Lieberman, 2018). The studies in the college students have shown that the caffeine consumption through soda has declined in the young adults, but has increases through coffee, energy drinks and diet soda or low- calorie soda

of more caffeinated beverages such as energy drinks, energy shots and sports drink and also recent studies showing new developments in the field of caffeine and health effects, it is important to study their intake in college students as this phase of life plays an important role in the development of long-term habits and lifestyle (Kvaavik, Anderson

& Klepp, 2005).

Statement of Problem

Caffeinated beverage consumption has been increased over the years in college students with introduction of new beverages such as energy drinks, energy shots, and caffeinated sports drinks. Most dietary caffeine is provided by beverages (Fulgoni III,

Keast & Lieberman, 2010). Ninety-eight percent of caffeine consumed comes from beverages, with coffee, tea, and soda being the predominant sources (Fulgoni III, Keast &

Lieberman, 2010). Acute high amount of caffeine can cause adverse effects and intoxication. The adverse effect can include nausea, jitters, headaches, sleep disorders, hyperactivity, agitation, whereas; chronic high intake of caffeine affects heart health, liver health, bone health, fertility in women (Heckman, Weil & DeMeija, 2010). Sugar

(generally in the form of high fructose corn syrup) is the another important component after caffeine in the caffeinated beverages (Johnson, Appel, Brands, Howard, Lefevre,

Lustig,….Wylie-Rosett, 2009). Added sugar from beverages provides empty kcal, without decrease in the kcal from other dietary sources, therefore being one of the leading causes of obesity (Malik, Popkin, Bray, Després & Hu, 2010). Twelve ounces of soda provide 40-50g sugar in form of HFCS, which is equivalent to 10 teaspoons of sugar

(Malik, Schulze & Hu, 2006)

Recently, new beverages such as energy drinks and energy shots have been introduced in the market. These products that contain higher amounts of caffeine compared to traditional caffeinated beverages including coffee, tea, and soda have gained popularity among this young population. With increasing concerns regarding high intake of caffeine as well as sugar from various caffeinated beverages, various studies have investigated caffeine beverage intake in US population. Very few studies, however, focused on the young adults who develop their own dietary habits and lifestyle during college years which will remain stable throughout their later adulthood. Also, the effects of caffeine s dose-dependent and not many individuals are aware about it and thus this increases the total caffeine intake in order to get benefits from it. But if consumed in higher amount, it can have adverse effects rather than being beneficial. Therefore, it is important to understand a pattern of caffeinated beverage intake in college students to help health professionals develop nutrition interventions for healthy beverage choices in this population.

Purpose Statement

The purpose of this study is to evaluate the consumption pattern of caffeinated beverages in the undergraduate students at a public mid-western university.

Hypotheses

1. Sugar intake will be higher in consumers than non-consumers.

2. Water consumption will be high in consumers than the non-consumers.

3. Total energy intake will be more in consumers than the non-consumer.

Operational Definitions

Undergraduate students: Individual within the age range of 18 to 25 years old are considered as college students.

Consumers: The students who are consuming any type of caffeinated beverages.

Non-consumers: The students who are not consuming any caffeinated beverages.

Total energy intake: Total energy content of foods and beverages consumed.

Expressed in kcals.

Consumption pattern: The trend of food and beverage intake in specific population.

Added sugar: The sugar and syrups added during the processing or preparation of the foods or beverages.

CHAPTER II

REVIEW OF LITERATURE

Caffeine

Caffeine is the most widely consumed psychoactive substance worldwide.

Caffeine can be found in coffee, tea, carbonated beverages, chocolate, medications including appetite suppressants for weight loss, diuretics, analgesics, and decongestants and it is the most popular drug that acts on the nervous system as a stimulant. The amount of caffeine in any food, beverages, or medications are not regulated. Approximately 85% of Americans consume caffeine every day (Barone & Roerts, 1996; Donovan & DeVane,

2001; Fray, Johnson & Wang, 2005; Fulgoni III, Keast & Lieberman, 2015).

Structure

Caffeine has the molecular formula C8H10N4O2 with various chemical names such as 1,3,7- trimethyxanthine, 1H-Purine-2,6-Dione, 3,7-dihydro-1,3,7-trimethyl, methyltheobromine, 1,3,7- Trimethyl-1-2, 6-dioxopurine and 7- Mehtyltheophylline and has the International Union of Pure and Applied Chemistry (IUPAC) name as 1,3,-7 trimethylpurine-2,6-Dione (“National Center for Biotechnology Information”, 2019;

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Weinberg & Bealer, 2001). Caffeine is a methylxanthine belonging to the chemical class xanthine. It has a molecular weight of 194.194 gram/ Mol, and in the pure form exists as dry powder. It is bitter in taste, odorless, and has boiling point of 178° C and melting point of 238° C. Caffeine is completely soluble in hot water and moderately soluble in water at normal temperature (Weinberg & Bealer, 2001). Figure 1 shows the molecular structure of caffeine.

Figure 1. Molecular Strucure of Caffeine

Adapted from Caffeine.svg. (2017, August 8). Wikimedia Commons, the free media repository. Retrieved 00:43, March 9, 2019 from https://commons.wikimedia.org/w/index.php?title=File:Caffeine.svg&oldid=25467

9985.

Half-life

The half-life of caffeine depends on the rate of metabolism, and rate of metabolism varies in every individual, so half-life can range from two to twelve hours in healthy adults (Benowitz, 1990). Tmax, the time in which maximum plasmic concentration is obtained, is 30-45 minutes during the fasting and it is delayed with food ingestion

(Bispo, Veloso, Pinheiro, DeOliveria, Reis & Andrade, 2002; Fredholm, Bättig, Holmén,

Nehlig & Zvartau, 1999; Nehlig, 1999). Half-life of caffeine is four to six hours on average, with shorter time in smokers and longer in individuals with chronic liver disease, pregnant women, and infants (Benowitz, 1990).

Absorption, Metabolism and Excretion

. Caffeine is 100% bioavailable because it is rapidly and completely absorbed from the intestinal tract (Benowitz, 1990). Caffeine is highly soluble in lipids, and it can cross the blood- brain barrier both by diffusion and by a saturable transport system rapidly (Axelord & Reisenthal, 1953; McCall, Millington & Wurtman, 1982). This increases metabolic rate, heart rate, serotonin secretion, epinephrine/ norepinephrine secretion, gastric secretion, smooth muscle relaxation, skin temperature, muscle contractibility, and urinary output. Caffeine is metabolized in the liver into more than 25 metabolites with a majority of three metabolites: paraxanthine, theobromine, and theophylline (Bonati, Latini, Galletti, Young, Tognoni & Garattini, 1982; Etherton &

Kocher, 1993). Paraxanthine represents 72%-80% of caffeine metabolism, theobromine represents 12% and theophylline represents 4%. Caffeine metabolism includes mainly five metabolic pathways. The first three metabolic pathways include breakdown of caffeine into paraxanthine, theophylline and theobromine through demethylation. The fourth pathway forms uracil metabolites by an oxidation process of caffeine metabolites and the fifth pathway consists of renal elimination of the remaining caffeine, which was not able to be degraded (Miners & Birkett, 1996; Lozano, García, Tafalla, & Albaladejo,

2007). It is shown by the research that approximately 90% of the caffeine from one cup

of coffee is cleared from the stomach within 20 minutes and peak plasma concentration is reached within approximately 1 to 1.5 hours (Nawrot, Jordon, Eastwood, Rotstein,

Higenholtz & Feely, 2003). Caffeine, mainly as paraxanthine, travels throughout the body tissues and secretions from breast milk, saliva, and semen (Chambers, 2009; Payne,

Schacter, Propper, Huang, Wamsley, Tucker, ... & Stickgold, 2009; Weinberg & Bealer,

2001).

Figure.2. Caffeine Metabolism

Adapted from Vuong, Q. V. (2014). Epidemiological evidence linking tea consumption to human health: a review. Critical reviews in food science and nutrition, 54(4), 523-536.

Factors affecting Metabolic Rate

Caffeine metabolism can be slowed by alcohol, Asian ethnicity, oral contraceptives, liver damage, high altitudes, pregnancy, and it can be increased by cigarettes, and Caucasian ethnicity (James, 1997; Weinberg & Bealer, 2001).

Functions of Caffeine

Caffeine plays an important role in the intracellular mobilization of calcium, inhibition of phosphodiesterases and antagonism at the level of adenosine receptors

(Benowitz, 1990).

Mobilization of Intracellular Calcium. A caffeine concentration of 1-2 mm lowers the threshold and extends the duration of the active period of muscle contraction by promoting translocation of calcium through the plasma membrane and sarcoplasmic reticulum; this was first discovered in skeletal muscle (Bianchi, 1961; Bianchi, 1968,

Bianchi, 1975; Nehlig, Daval & Debry, 1992). On the isolated cerebral endoplasmic reticulum, caffeine shows biphasic effect on calcium shifts. Low or moderate amounts of methylxanthine stimulate both the uptake and release of calcium by the endoplasmic reticulum (Mekhail-Ishak, Lavoie & Sharkawi, 1987, Trotta & Freire, 1980).

Inhibition of Phosphodiesterases. Phosphodiesterases are the enzymes, which breaksdown phosphodiester bond in c-AMP (cyclic adenosine monophosphate), which is the secondary messenger required for the various signaling processes at the cellular level.

It was observed that methylxanthine stops the enzymatic breakdown of c-AMP by inhibiting cyclic nucleotide phosphodiesterase (Beavo, Rogers, Crofford, Hardman,

Sutherland & Newman, 1970; Butcher & Sutherland, 1962). This inhibition occurs only with millimolar concentration of methylxanthines, which is usually never found in situ

(Cardinali, 1980; Wachtel, 1982; Weiss & Hait, 1977). Chronic intake of caffeine at the dose of 25 mg/kg/day does not increase intracellular concentration of c-AMP and thus does not decrease specific activity of the specific phosphodiesterases of cerebral cyclic nucleotides (Burg & Werner, 1975).

Effect on Nervous System. Adenosine, a locally released purine hormone, acts on different receptors (A1 and A2) that can increase or decrease cellular concentrations of c-AMP. The action of adenosine includes inhibition of neuronal release of acetylcholine, norepinephrine, dopamine, gamma amino butyric acid, and serotonin, thus produces sedation and has anticonvulsant activity (Fredholm et. al., 1999). Action of adenosine can be inhibited by caffeine at concentrations found in people consuming caffeine from dietary sources. Caffeine shows antagonist actions on adenosine receptors as it has the molecular structure similar to adenosine (Fisone, Borgkvist & Usiello, 2004) and thus stops the function of adenosine. A1 receptors are found in all parts of the brain with the highest concentration in the hippocampus, cerebral and cerebellar cortex and thalamic nuclei. A2 receptors are found in the dopamine rich areas of the brain (Fredholm et. al., 1999). When caffeine attaches to the adenosine receptors, it releases norepinephrine, dopamine, and serotonin in the brain and increases circulation o catecholamones responsible for reversal of the effects of adenosine. The sleep promoting effects of adenosine are inhibited, resulting in the neurons speeding uo instead of slowing down (Ferré, 2008; Fredholm et. al., 1999).

Sources of Caffeine

Caffeine could be found in more than 60 plant species, some common sources of caffeine include kola nut (Cola acuminate), cacao bean (Theobromine cacao), Yerba mate

(Ilex paraguariensis), Guarana berries (Paullinia cupana), and the primary sources been roasting coffee beans (Coffee Arabica & Coffee Robusta) and tea leaves (Camelia sinensis) (Barone & Roberts, 1996). Caffeine is consumed mostly from beverages such as tea, coffee, soft drinks, energy drinks, sports drinks, juices and water. It has been reported that 250-350 mg tea has 3-6% caffeine, caffeine in coffee varies according to the brewing method and type of coffee seeds used; for example espresso has 72.7-136 mg/ fl.oz of caffeine whereas home brewed has 18.18-21 mg/ fl .oz caffeine. Soft drinks have caffeine amount limited to 71mg/ 8 oz. For energy drinks, caffeine varies according to the brand, generally ranging from 50 mg to 550 mg. In sports drinks, juices, and water caffeine is rarely used (Channel Check, 2008). It can also be found in cocoa, chocolate, dietary supplements and medicines (Spiller, 1998; Weinberg & Bealer, 2001).

Safe Limit for Caffeine Intake

Caffeine’s intake has been controversial over the years. Caffeine intake more than

500-600 mg can be harmful for the body. Research shows that it has negative effects such as tachycardia, anxiety, restlessness, and tremors due to intoxication (Ribeiro &

Sebastiao, 2010). However, there are studies showing that if caffeine intake is within safe limits, it causes no harm to the human body, and can be beneficial for sports performance, mental health, and in treating Parkinson’s disease (Blandini, Nappi,

Tassorelli & Martignoni, 2000; Clark 1997; Nawrot et. al., 2003; Trevitt, Kawa, Jalali &

Larsen, 2009). The moderate daily caffeine intake for the healthy adult population is considered to be ≤ 400 mg (equivalent to 6.5 mg/ kg bw/d for a 70 kg person). A child should consume ≤2. 5 mg/ kg bw/d and pregnant women should limit their intake of caffeine to ≤300 mg/d (equivalent to 5 mg/kg bw/d for a 70 kg person), as it could pass the placenta through blood, and can affect the health of fetus adversely). In the females, high caffeine intake can cause infertility (Nawrot et. al., 2003). Chronic high intake of caffeine can affect heart health, bone health fertility in women, heart health, and respiratory issues. (James, 1997; Schellack, 2012). The effect of caffeine in every individual depends on the rate of gastric evacuation, intestinal absorption, lifestyle habits, and body weight (Flory & Gilbert, 1943; Higden & Frei, 2006).

Caffeine Tolerance/ Withdrawal

Caffeine withdrawal occurs when intake of habitual caffeine in the individual is discontinued abruptly. Some symptoms of caffeine withdrawal includes impaired behavioaral and cognitive performance, decrease or increased blood pressure, decreased motor activity, increased herat rate, hand tremoe, increased diuresis, skin flushing, flu- like symptooms, nausea/ vomiting, constipation, muscle stiffness, joint pains, and abdominal pain (Sajadi-Ernazarova, & Hamilton, 2017) Caffeine tolerance develops very quickly after heavy doses. Four hundred mg of caffeine 3 times a day for 7 days can cause tolerance to sleep disruption and 300 mg of caffeine 3 times per day for 18 days builds tolerance to subjective effects of caffeine (Riberio & Sebastiao, 2010). The habitual caffeine users are more tolerant towards the short term effect of caffeine on cognitive performance. Cessation of daily caffeine intake can cause several symptoms

such as headache, tiredness/ fatigue, decreased alertness, decreased energy, difficulty concentrating, drowsiness, pain in the stomach, upper body, and joints (Juliano &

Griffiths, 2004; ). After discontinuation of caffeine for 12 to 24 hours, the peak is obtained at 48 hours, and usually lasts from one to five days. Meaning that this is the time required for the number of adenosine receptors in the brain to return to their normal levels (Fredholm et al., 1999, Riberio & Sebastio, 2010).

Caffeinated Beverages

Caffeinated Beverages are the beverages that have a caffeine source along with other ingredients such as water, milk, added sugar, and electrolytes. Such beverages include tea, coffee, energy drinks, soft drinks, sports drinks, and cocoa beverages.

Tea

There are two different types of teas: herbal teas and teas made from the leaves of

Camelli sinensis, an evergreen bush from both China and India (Khan & Mukhtar, 2013)

Tea, consumed by two-thirds of the world’s population, is the most popular beverage because of its attractive aroma, exceptional taste, health promoting, and pharmaceutical potential (Gramza-Michałowska, 2014; Khan & Mukhtar, 2013).

Types. Teas made from the leaves of Camelli sinensis are classified into different types of teas depending on the processing of the leaf harvested: black, green, oolong and white tea (Khan & Mukhtar, 2013; “United Sates Patent and Trademark Office”, 2017).

There is a three-step process involved in the production of tea: withering, fermentation, and drying. Fermentation is a major part of the process that determines a type of the tea

produced (Khan & Mukhtar, 2013). White tea is made from mostly growth buds that have undergone minimal fermentation. The growth buds used for white tea production are shielded from sunlight to prevent the formation of chlorophyll so that they are not converted to tea leaves and they can be sold as tea bags or loose tea (“United Stated

Patent and Trademark Office, 2017”). For production of green tea, the young tea leaves are withered, steamed or pan fried, dried and graded. The steaming process destroys the enzymes responsible for breaking down the color pigments in the leaves and allows the tea to maintain its green color during the subsequent rolling and drying processes. At this point, the leaves are commercially sold as green tea without the fermentation process.

Black tea is produced when they undergo the fermentation process before being dried.

Oolong tea is the semi-fermented tea because leaves are allowed to undergo only partial oxidation or fermentation (Khan & Mukhtar, 2013; Mukhtar & Ahmad, 2000). Herbal teas are any Camellia sinensis free product or beverage which is prepared by hot water infusion of plant material, usually leaves but also includes fruits, flowers, and possibly even bark or other parts. Herbal tea belongs to the group of tea substitutes (“United States

Patent and Trademark Office, 2017”). There is no caffeine found in herbal teas of linden and chamomile (Gramza-Michałowska, 2014).

Processing. Withering is a process to cause damage to the cell wall by rolling, tumbling or maceration of harvested leaves, which initiates oxidation, or fermentation

(Gebely, 2012). Fermentation is a process in which chemicals in the leaves are broken down by enzymes in the presence of yeast. The degree of fermentation determines chemical composition of tea (Heiss & heiss, 2007; Khan & Mukhtar, 2013). The longer

tea leaves are fermented, the darker the leaves become, the deeper the aroma that develops and there is an increase in caffeine content. During the fermentation, a series of chemical reactions occurs in which catechin, a major polyphenol in teas, is converted to theaflavins by polyphenol oxidase and peroxidase. (Heiss & Heiss, 2007). Theaflavins are then converted to thearubigins, compounds that are responsible for changing the leaf color from green to golden, coppery or chocolate brown (Heiss & Heiss, 2007).

Chlorophylls, a pigment that gives the green color to tea leaves, are converted to pheophytins and pheophorbides during fermentation enhancing the flavor of teas. Also, lipids, amino acids, carotenoids and sugars in teas degrade to produce the tea flavors and aroma (Gebely, 2012).

The last step is the drying, a step to stop the fermentation process. Drying deactivates enzymes (Gebely, 2012; Khan & Mukhtar, 2013) when the desired level of fermentation is achieved (Heiss & Heiss, 2007). The drying of leaves can be done through: pan frying, steaming, heating in tumblers, baking in ovens, sun drying, or microwaving.

Composition. Tea contains polyphenols, alkaloids (caffeine, theophylline and theobromine), amino acids, carbohydrates, proteins, some minerals, trace elements, chlorophyll, and volatile organic compounds that contribute to the odor of tea (Cabrera,

Giménez, & López, 2003). The polyphenols of fresh leaves are relatively simple and composed of four major catechins: epicatechin, epigallocatechin and their galloyl esters.

Out of all catechins, epigallocatechin is the most active compound (Reto, Figueira, Filipe,

& Almeida, 2007). Concentration of polyphenols in tea beverages depends on the type of

tea, the brew time, and the temperature. Polyphenols, known to have antioxidant properties and anti-cancerogenic properties, inhibits the growth of cancer cells and kills them without harming the healthy cells. It is also known to lower Low-Density

Lipoproteins (LDL) cholesterol level, inhibiting the abnormal formation of blood clots and thus reducing the cardiovascular diseases, reduction of platelet aggregation, lipid regulation, inhibition of smooth muscle cells, aide in rheumatoid arthritis, infection and impaired immune function, and helps in DNA repair (Katiyar & Elmets, 2001; Katiyar,

Elments & Katiyar, 2007). Green tea has more anti-oxidant activity than black tea or the oolong tea because the fermentation carried out to produce black tea and oolong tea breaks down the polyphenols.

Caffeine Content. A typical cup of green tea usually contains 250-350 mg of tea solids of which 30-42% are catechins and 3-6% caffeine (Khan & Mukhtar, 2013). The

85% fermentation process of tea increases the level of caffeine from 8.69 to 16.03 mg/

100 mg of dry leaf weight (Lin, Lin, Liang, Lin-Shiau & Juan, 1998). Black tea, more oxidized tea, has 4.8% of dry weight and non-fermented tea such as green tea has 3.8% of the dry weight of caffeine (Fernández, Pablos, Martin & González, 2002). Caffeine content in the black tea is approximately 64 to 112 mg/ 8 fl. oz, green tea has 24 to 39 mg/ 8 fl. oz, oolong tea has 29 to 53 mg/ 8 fl. Oz, and white tea contains 32 to 37 mg/ 8 fl. oz. (Cabrera, Artacho, & Giménez, 2006; Chin, Merves, Goldberger, Sampson-Cone,

& Cone, 2008). It was also shown by Hilal and Engelhardt (2007) that black tea has nearly two times higher the level of caffeine than green tea and 30% higher level than white tea.

Caffeine content also varies on the preparation method. Brewed hot tea has the highest amount of caffeine compared to instant tea. Iced and ready to drink teas have the least caffeine content (Cabrera, Giménez, & López, 2003). Teas were brewed for a second time under same conditions and it was found that the caffeine content was decreased by 50% and for the third time, there was further decrease of 50% of caffeine.

There was a 50% decrease in the caffeine content of the first time and the third time brewed further decreased the caffeine content by 50%. (Horžić, Komes, Belščak, Ganić,

Iveković, & Karlović, 2009).

There are other various essential factors which affect the chemical composition of tea leaves and their infusion such as tea cultivar, species of tea shrub or tree, season of collecting, leaves age, climate, geochemical composition of the soil and cultivating method, environmental pollution, drying conditions and technological production processes (Fernández et al., 2002; Wang, Kim, & Lee, 2000). Tea leaf maturity also affects the caffeine content. It was shown by Owuor and Chavanji that there is a difference of 20-40% caffeine concentration based on the tea leaves age. Caffeine has always been higher in young leaves than the older ones (Owuor & Chavanji, 1986). Tea forms (leaves or bags) also affect the caffeine extraction at a significant level. Caffeine extraction from tea leaf shows stability, but the extraction from tea bags varies due to the tea bag’s paper quality affecting beverage quality (Yao, Liu, Jiang, Caffin, D’Arcy,

Singanusong, ... & Xu, 2006). Also, the temperature of water affects the caffeine extraction. Hot water is more effective than the cold water (Lin, Liu, & Mau, 2008). Tea

contains more caffeine than coffee, but a 30 % decrease per cup occurs because of the brewing process (Barone, & Roberts, 1996).

Consumption Data. Tea is the second most consumed beverage worldwide after water being the first one. According to the statistical data, Turkey has the highest number of tea consumers in the world. In the United States, the per capita consumption of tea amounted to approximately 8.26 gallons in 2015 (“statisa”, n.d). The survey, conducted in 2017, in the United States, showed that 31% of consumers had two to three cups of tea

(7 oz) per day on average (“statisa”, n.d). Overall market in the US is growing with one percent increase in total tea imports. The ready to drink tea market has increased by 3-4% and amounts to approximately 45.7% of the tea market in 2017 (Goggi, n.d). Iced tea is the preferred choice in the U.S., and it accounts for approximately 85% of the tea consumed. In terms of varieties, 84% of the tea consumed was black tea, 15% was green tea and the remaining portions accounts for oolong, white and dark tea (Bailey, 2015).

According to a survey by pollster YouGov, tea is equally popular as coffee among 18 to

29 years old with 42% opting for tea and 42% for coffee and remaining percentage belonging to other beverages.

Coffee

Coffee is a beverage made from roasted seeds, commonly called coffee beans, which comes from a plant of the genus Coffea (“United States Patent and Trademark”,

2017).

Types. Coffee plant is an evergreen shrub which belongs to Rubiaceae family and grows in the tropical and sub-tropical regions worldwide. Out of all the species under genus Coffea, there are two species that are used in the production of the beverage

Coffee: C. Arabica (Arabic coffee) and C. Canephora (Robusta coffee). Among all the species, C. Arabica is the most important commercial species contributing to almost 70% of the market worldwide. (“International Coffee Organization”, 2011; “United States

Patent and Trademark, 2017”). There are various differences between Arabic and

Robusta coffee, including their ideal growing climates, physical aspects, chemical composition, and characteristics of the brew made with the ground roasted seeds (Farah,

2012). Robusta coffee is more robust, stronger, more pests resistant, disease resistant, and less demanding with regard to climate and also, they are high in anti-oxidant and caffeine than Arabica. Arabica gives more superior cup quality and aroma compared to Robusta coffee (“International Coffee Organization”, 2011). The coffee plant takes approximately four years for green coffee berries (green coffee beans or coffee cherries) to ripen. After harvested, coffee beans go through a multiple step process before they are used to make coffee (“National Coffee Association”, n.d).

Harvesting. Harvesting of the coffee beans can be done in three ways: picking, stripping or mechanical harvest. In the picking method the ripe fruit or cherries are hand- picked, making it a tedious process, but this gives a better quality of coffee beans with regard to both taste and health. Manual stripping of the twigs collects the immature, ripe and overripe seeds along with leaves. Mechanical harvesting is the method in which

either the trees are shaken or branches are stripped is done by using the apparatus similar to flexible comb (Farah, 2012).

Processing. There are various steps involved in the processing of coffee beans.

The dry Method is an old-aged method and generally used where the water resources are limited. In this method, the coffee beans are sun-dried till the moisture content is approximately 10% -12% (Toci, Farah & Trugo, 2006). The wet method is more sophisticated and gives a higher quality brew (Flament, Gautschi, Winter, Willhalm &

Stoll, 1968). In this method, the pulp is removed, then the beans are transported to large water-filled fermentation tanks and kept in those tanks for anywhere from 12 to 48 hours

(“National Coffee Association”, n.d). In this fermentation tank, enzymes are added which removes the parchment skin, increasind acidity, and decreasing the pH down to 4.5

(Flament et al., 1968). After beans are dried and milled, coffee beans are roasted which gives characteristic aroma and flavor of coffee (Farah, 2012; “National Coffee

Association”, n.d). During this roasting process, the caffeine is lost by 30% (Arion,

Canfield, Ramos, Schindler, Burger, Hemmerle… &Herling, 1997; Svilaas, Sakhi,

Andersen, Svilaas, Ström, Jacobs,... & Blomhoff, 2004). Next step is the grinding of the coffee beans. It has been noted that the coffee powder loses 60% of its aroma in the first

15 minutes of grinding (Derossi, Ricci, Caporizzi, Fiore, & Severini, 2018). How long the grounds will be in contact with water determines the ideal grade of grind; the finer the grind, the more quickly the coffee should be prepared, and because of this reason, coffee ground for espresso is much finer than coffee brewed in a drip system. (“National Coffee

Association”, n.d).

Brewing Methods. Brewing, the last step to have coffee as a beverage, is a process in which the water is in contact with the coffee grounds. The amount of time the water and ground has been in contact is an important flavor factor and influences the caffeine content also (Bell, Wetzel, & Grand, 1996; “National Coffee Association”, n.d).

The most common brewing methods worldwide are simple percolation, boiled coffee, electric coffee maker, espresso machine, Italian coffee maker, and French press. All these methods affects the aroma, flavor, and caffeine content because they have different water to ground ratio, different or no pressure applied, and temperature of the water differs. In the simple percolation, medium-ground coffee is evenly spread on a paper, cloth or nylon filter set on a support, and hot water is poured over the coffee in a circular motion toward the center of the filter (Farah, 2012). Turkish coffee or the boiled coffee is the most ancient preparation method of coffee brew. The roasted beans or finely ground beans boil in the water and poured directly into the cup when the mixture starts boiling. (Galeazzi,

2009; Küçükkömürler, & Özgen, 2009). Electric coffee maker or Drip filter or American coffee brew is prepared by using automatic machine which has a tank filled with water heated at 92°C- 96°C and a container in which using a single-use paper filter, the roasted coffee powder is placed and it takes approximately 10 -12 minutes to prepare the coffee

(Farah, 2012). Espresso can be defined as a brew obtained by percolation of hot water under pressure through a compacted cake of roasted ground coffee, where the energy of the water pressure is spent within the cake. It is prepared by placing coarse- or medium- ground coffee and water in their respective compartments. Water is supposed to be boiled to 90°C- 95°C and have a pressure of about 9 atmospheric pressures applied for a short

extraction time of 30±5 seconds (Petracco, 2001; Derossi et al., 2018). In the preparation of Italian coffee or Moka or Mocha, kettle with a pressure valve is used to boil the water which percolates though the medium-ground coffee under pressure (Galeazzi, 2009;

Navarini, Nobile, Pinto, Scheri, & Suggi-Liverani, 2009). French Coffee also known as the European coffee is prepared by using a French press, the coarse roasted coffee powder is soaked in hot water for two to five minutes and then it passes through wire- mesh filter towards the bottom of the tank and then it is poured into the cup (Galeazzi,

2009).

Composition. The composition of green coffee beans is affected by intrinsic factors such as genetic aspects and physiologic aspect, such as maturation (Farah, 2012).

Extrinsic factors such as soil composition, climate, agricultural practices and storage conditions affects seed physiology, and chemical composition to a less extent (Farah &

Donangelo, 2006; Perrone, Neves, Brandao, Martinez, & Farah, 2009). Coffee bean is composed of non-volatile compounds such as water, carbohydrate, fiber, proteins, free amino acids, lipids, minerals, diterpenes, cholorogenic acids, trigonellic and caffeine and volatile compounds such as alcohols, esters, hydrocarbons, aldehydes, ketones, pyrazines, furans and Sulphur compounds (Clarke, 2003; Clifford, 2000; Farah & Donangelo, 2006;

Farah, de Paulis, Moreira, Trugo & Martin, 2006; Fischer, Reimann, Trovato &

Redgwell, 2001; Speer & Kölling- Speer, 2006; Toci & Farah, 2008).

Trigonelline. Alkaloid trigonelline in coffee beans contributes to the bitterness of the brew and is a precursor for the formation of various different classes of volatile compounds such as pyrroles and pyridines (Flament et al., 1968). Biologically,

trigonelline is known to inhibit the invasiveness of cancer cells, and regenerate dendrites, and axons showing that it may improve memory (Flament et al., 1968; Hirakawa,

Okauchi, Miura, Yagasaki, 2005; Tohda, Kuboyama & Komatsu, 2005).

Chlorogenic Acids. Chlorogenic acids are comprised of a major class of phenolic compounds: caffeoylquinic acids, dicaffeoylquinic acids, feruloylquinic acid, and less abundant p-coumaroylquininc acids and caffeoyl-ferulolyquinic acids. Chlorogenic acids give astringency, bitterness, and acidity to the coffee brew (Farah, Monteiro, Calado &

Trugo, 2006). They also have some pharmacological properties such as anti-viral activity against adenovirus and herpes virus (Chiang, Chiang, Chang, Ng & Lin, 2002). Robusta coffee has almost one and a half times higher concentration of chlorogenic acids than in

Arabica coffee (Farah, 2012).

Diterpenes. Cafestol, major type of diterpenes, is found mostly in the coffee oil

(Flament et al., 1968). Cafestol have shown anticarcinogenic and hepatoprotective properties in vitro (Cavin, Holzhaeuser, Scharf, Constable, Huber & Schilter, 2002; Lee,

Choi & Jeong, 2007; Wattenberg, 1983). Research, however, also shows that high amount of this compound elevates homocysteine and low-density lipoprotein levels in human plasma, thus increasing the risk of cardiovascular disease (Olthof, Hollman, Zock

& Katan; 2001). As they are poorly soluble in water, they are found more in the unfiltered coffee as they are trapped by paper filters.

Other components present in coffee affects the aroma, flavor and freshness of the coffee beans and they include: water (8.5% - 12%), carbohydrate (more than 50% of the

dry weight), some minerals and small amount of lipids (Farah, 2012). Sucrose contributes to flavor, quality of coffee, and contributes up to 9% of dry weight in Arabica coffee and approximately half of it in Robusta (Farah, 2012). Major minerals found in coffee beans are potassium (40%), phosphorous (4%) and magnesium and there are other approximately 30 different other elements (Clarke, 2003; Costa, Toci, Silveira, &

Herszkowicz, 2010). Arabica coffee beans have twice of lipid content than Robusta coffee beans (Stephanucci, Clinton & Hamel, 1979). Robusta coffee has around 10% of lipid content and Arabica coffee beans has approximately 15% of lipid content and out of total lipid fraction, coffee contains mainly of triacylglycerols (75%) (Fischer, Reimann,

Trovato & Redgwell, 2001; Wilson, Petracco, & Illy, 1997). Fatty acids in coffee beans play role in keeping the coffee fresh by avoiding staleness caused by oxidation of triacylglycerols (Toci, Neto, Torres, Calado & Farah, 2009).

Because of pyrolysis, caramelization and Maillard reactions which occurs during the roasting process, various compounds are destroyed and many new compounds are formed. The final composition of roasted coffee depends on the raw material, roasting degree, roaster type and the time, temperature, and airflow speed in the roasting chamber

(Farah, 2012). The moisture content of roasted coffee beans is much lower than that of green coffee (Trugo & Macrae, 1984). Maillard reaction produces melanoidins which are responsible for the brown color of roasted coffee and show antioxidant, anti-bacterial, and metal- chelating properties (Bekedam, Loots, Schols, Van Boekel & Smit, 2008;

Daglia, Cuzzoni & Dacarro, 1994; Daglia, Papetti, Gregotti, Berté & Gazzani, 2000;

Nicoli, Anese, Manzocco & Lerici, 1997). Chlorogenic acids are thermal instable and

undergoes many changes such as isomerization, epimerization, lactonization, degradation, and depending on the roasting degree, the total chlorogenic acid content is reduced to less than 1% of the original content (Farah, 2012). Caffeine is not significantly altered during coffee roasting, but small losses can occur due to sublimation (Farah,

2012). A lipid fraction of the coffee beans is relatively heat stable and thus not affected much by the roasting (Farah, 2012).

Caffeine Content. Caffeine is a major constituent of coffee beans with bitter characteristics and contributes 10% of the perceived bitterness of the coffee beverage

(Flament et al., 1968). Caffeine is a heat stable alkaloid found twice as much in Robusta than in Arabica coffee (Mussatto, Machado, Martins, & Teixeira, 2011). Studies have shown that the caffeine content can vary because of the brewing method primarily (as shown in Table 1).

Factors Affecting the Caffeine content. Caffeine contents in coffee vary depending on coffee beand varieties, roasting and grinding degrees, extraction time, roasted ground coffee/ water mass ratio, the extract volume as well as water temperature, the vapor pressure in case of espresso coffee, filtration, boiling process, the type of contact between water, and coffee ground (brewing method) affects the caffeine content

(Díaz-Rubio & Saura-Calixto, 2007; Farah, Perrone, Fernandes & Silanes, 2010;

Gntechwitz, Reichardt, Blaut, Steinhart & Bunzel, 2007; Ortiz, Ortiz, Veja & Posada,

2004). Also, the volume of the brew in a cup is variable exhibiting the wider variance mostly because of personal choice. For instance, coffee cup can vary from the “Ristretto

espresso coffee” of about 15-20 ml to the “American filtered coffee” of 125-400ml

(Bekedam et al., 2008; Olthof et al., 2001).

Table 1

Caffeine content in coffee on the basis of brewing methods

Brewing Method Caffeine Content (mg/ fl. oz)

Espresso 72.7-136

Turkish or Boiled 58.7

Italian 48.48

Home Brewed 18.18-21

Mocha 21.21-163.6

American or Filtered 12.12-42.42

French 6.06-15.15

Adapted from Caffeine Informer. (n.d). Caffeine Content of the Drinks. Retrieved from https://www.caffeineinformer.com/the-caffeine-database

Consumption Data. The coffee drinkers in America has increased from 57% in

2016 to 62% in 2017. On the basis of age, there was increased from 31% in 2016 to 37% in 2017 in the age group 13 to 18 years old, in 19 to 24 years old, the increase was up by

2%, making it 50% of consumers in 2017, 25 to 39 year old showed growth by 3%, making it to 63%, individuals belonging to the of 40-59 year old, showed increase from

53% to 64% in 2017 and 60+ showed increase from 64% to 65% in 2017. The use of single-brew has been increased showing that 33% of American households now use single-cup brewer, which was 29% in 2016. One of the National Coffee Drinking Trends

(NCDT) report also shows that 59% of the coffee consumed were gourmet, majorly contributed by espresso-based drinks by 24%, 11% by cold brew, frozen blended with

14%, and remaining portion by other types of coffee (“National Coffee Assocaition”, n.d.). The survey done by statista also shows that the 44% of the Americans had two to three 7 fl. oz of coffee, 26% Americans had one cup or less 7 fl. oz of coffee and 16% had four to five cups of 7 fl. oz of coffee per day (“Statisa”, n.d).

Energy Drinks

Energy drinks are beverages with the combination of caffeine (the principal active ingredient), other plant-based stimulants (e.g. guarana, yerbamate), simple sugars (e.g.

Glucose, fructose), glucuronolactone (a naturally occurring glucose metabolite), amino acids (e.g. taurine, carnitine, creatine), herbs (e.g. ginkgo giloba, ginseng) and vitamins, which are marketed for improving energy, aid in weight loss, increase stamina, athletic performance, and concentration (Lee, 2011; McCarthy, 2011; O’Brien, McCoy, Rhodes,

Wagonen & Wolfson, 2008). Energy drinks are consumed by an individual to provide an extra boost in energy, promote wakefulness, maintain alertness, provide cognitive, and mood enhancement (Ishak, Ugochukwu, Bagot, Khalili, & Zaky, 2012). Energy shots are the drinks, which have caffeine content approximately five times greater than the caffeine content in 8 oz to 16 oz energy drinks (Cannon, Cooke, & McCarthy, 2001; “Federal

Institute of Risk Assessment, 2009; Reissig, Strain, & Griffiths, 2009).

Composition. Energy drinks mostly contain caffeine, taurine, l-carnitine, carbohydrate, glucuronolactone, vitamins, ginseng, guarana, yerba mate, and cocoa

(Seifert, Schaechter, Hershorin, & Lipshultz; 2011).

Taurine. Taurine is a sulfur containing amino acid and also the naturally found in abundance in the human body, mainly in the retina, skeletal, and cardiac muscle tissue

(Imagawa, Hirano, Utsuki, Horie, Naka, Matsumoto, & Imagawa, 2009; Timbrell,

Seabra, & Waterfield, 1995). Over the course of time, the content of the taurine in energy drinks has been reduced from 27% to 21% of total energy drink products. The reason behind this is quite unclear as it could be due to cost saving initiative or due to use of other ingredients. Taurine plays role in various physiological functions such as neuro modulation, cellular membrane stability, and modulation of intracellular calcium levels

(Brosnan & Brosnan, 2006; Huxtable, 1992, Timbrell, Seabra & Waterfield, 1995).

Taurine also enhances endurance performance, and helps in reduction of lactic acid buildup after exercise (Imagawa et al., 2009; Matsuzaki, Y., Miyazaki, Miyakawa,

Bouscarel, Ikegami, & Tanaka, 2002). The taurine analysis done on 80 different energy drinks has shown an average concentration of 753 mg of taurine/ 8 oz (Triebel, Sproll,

Reusch, Godelmann, & Lachenmeier, 2007). High intake of taurine has shown no adverse effect on the human body, however, research is still going on (Brøns, Spohr, Storgaard,

Dyerberg, & Vaag, 2004; Mantovani, & DeVivo, 1979; Sirdah, El‐Agouza, & Shahla,

2002; Zhang, Bi, Fang, Su, Da, Kuwamori, & Kagamimori, 2004).

Guarana. Guarana (Paullinia cupana), originated in the Amazon basin in Brazil

(da Silva Angelo, AMADO, YAMAGUISHI, LIRA, DO PERPÉTUO, ASTOFI-FILHO,

...& Porto, 2014). It is commonly known for fruit it produces, which has one to three dark seeds and seeds are the only edible part of the plant (Scholey & Haskell, 2008). Guarana has a significant amount of caffeine being equivalent to about 40 mg (Finnegan, 2003).

Along with caffeine, guarana plants also contain other alkaloids, high amounts of saponins, flavonoids, and tannins and they all show anti-oxidant activity (Espinola, Dias,

Mattei, & Carlini, 1997; Mattei, Dias, Espınola, Carlini, & Barros, 1998; Weckerle,

Stutz, & Baumann, 2003). Caffeine from guarana is released at a slower rate compared to pure caffeine, thus giving more subtle, and lengthier stimulatory effect. Due to this, the use of guarana has been increased in energy drinks in recent years (Scholey & Haskell,

2008). Guarana is related to improving cognitive performance, mental fatigue and induces lipid metabolism (Haskell, Kennedy, Wesnes, Milne, & Scholey, 2007; Kennedy,

Haskell, Robertson, Reay, Brewster-Maund, Luedemann,...&Scholey, 2008; Lima,

Carnevali, Eder, Rosa, Bacchi, & Seelaender, 2005; Scholey & Haskell, 2008).

Ginseng. Ginseng is an herb plant used widely in East Asian countries, including

China, Japan, and Korea as a remedy for various diseases and for promoting longevity

(Lee, Johnke, Allison, O'brien, & Dobbs Jr, 2005; Nam, Kim, Liu, Yang, Lim, Kwon, ...

& Park, 2005). Among all the species, Panax ginseng is most commercially used. The entire ginseng plant can be used for medicinal purposes; however, the root is the most important and dominated commercially, and they are harvested after fifth and sixth year of growth when their ginsenoside concentrations are at peak (Hu, 1976). Health benefits of ginseng include being an immune stimulant, and has anti-stress, anti-aging, antioxidant and anti-inflammatory properties (Lu, Yao, & Chen, 2009; Thompson Coon, &

Ernst, 2002). Some side effects of high doses of ginseng include hypertension, diarrhea and sleep disturbances (Thompson Coon & Ernst; 2002). However, there are studies showing that in comparison with other phyto-medicines, ginseng does not produce serious side effects or dangerous interactions with other drugs and is considered generally safe (Thompson Coon & Ernst, 2002; Nah, Kim, & Rhim, 2007).

Yerba mate. From Ilex paraguariensis plant, yerba mate is obtained (Heck, & De

Mejia, 2007). Yerba mate contains a variety of bioactive components such as polyphenols, xanthines, flavonoids, saponins, amino acids, minerals and vitamins, and has a high amount of caffeine, which is the primary reason for yerba mate to be incorporated into an energy drink. The caffeine concentration in 8 oz of yerba mate is equivalent to about 78 mg (Heck & De Mejia, 2007). Health benefits of yerba mate include anti-inflammatory, anti-diabetic, and anti-oxidant properties, it also plays a role in the management of obesity (Arçari, Bartchewsky, Santos, Oliveira, Funck, Pedrazzoli,

... & Carvalho, 2009; Bastos, Oliveira, Matsumoto, Carvalho, & Ribeiro, 2007; Heck &

De Mejia, 2007; Martins, Noso, Porto, Curiel, Gambero, Bastos, ... & Carvalho, 2010;

Pang, Choi, & Park, 2008). However, concerns have been raised regarding the association of yerba mate with the occurrence of certain types of cancer, but no conclusive evidence has been obtained (Heck & De Mejia, 2007).

B-vitamins. There are eight individual water- based vitamins, when grouped together they are known as B-complex and altogether plays important role in cellular processes. A regular energy drink can of 250 ml might contain 360% of the

Recommended Dietary Allowance (RDA) of vitamin- B6 (pyridoxine), 120% of vitamin

B12 (cyanocobalamin) and 120% of vitamin- B3 (niacin). In energy shots like 5-hour

Energy accounts for 8333% of RDA for vitamin – B12 (cyanocobalamin) and 2000% of

RDA for B6 (pyridoxine). Consumption of vitamin B complex increases mental alertness and improves mood (Heckman, Sherry, Mejia, & Gonzalez, 2010). Vitamin B2

(riboflavin) acts as a coenzyme in the metabolism of carbohydrates, vitamin B3 (niacin) plays an important role as a co-enzyme in energy metabolism, fat synthesis, and fat breakdown, vitamin B6 (pyridoxine) coenzymes aids in the utilization of carbohydrates, fat and proteins. Vitamin B12 (cyanocobalamin) assists in folate metabolism and in nerve function (Wardlaw, Allerhand, Doubal, Hernandez, Morris, Gow, ... & Deary, 2014)

Ginkgo Biloba Ginkgo Biloba is a plant product which helps with memory retention, concentration, circulation and acts as anti-depressants. The standard dose is 60 mg of Ginkgo Biloba but most energy drink does not have high or even standard dose of it. Side effects of Ginkgo Biloba include blood thinning, nausea, vomiting, diarrhea, headache, dizziness, heart palpitations and restlessness (“Energy Fiend”, 2009).

Milk Thistle. Milk thistle is used in few energy drinks and plays the role of liver detoxifying agents. It is used in energy drinks not for energy enhancing activity, but as a counter agent to mixing energy drinks with alcohol as milk thistle helps with hangovers and detoxing the liver from alcohol. But the study has also shown that milk thistle is not much of any benefit (Babu, Church, & Lewander, 2008).

Acai Berry. Acai berry is an ingredient of the Acai palm tree with origin in South

America and has a small amount of anti-oxidants, however, is mainly added for marketing purpose (“Energy Fiend, 2009”).

Caffeine Content. Different brands have varying caffeine content in energy drinks ranging from 50 mg to 550 mg per can or bottle (Reissig, Strain, & Griffiths,

2009). When drinks are packed as energy shots, the caffeine content could be approximately five times higher than in 8 oz of energy drinks (Cannon, Cooke, &

McCarthy, 2001; Reissig, Strain, & Griffiths, 2009; Federal Institute for Risk

Assessment, 2009). Popular energy drink brands include Red Bull, Monster, Rockstar,

NOS and AMP (Mitchell et al., 2015). The energy drink with highest amount of caffeine is redline energy drink with 316 mg caffeine/ 8 oz (“Caffeine Informer”, n.d).

5-hour Energy is most popular energy shot which contributes to almost 93% of the total energy shot market and has the caffeine content of 200 mg/ 2 oz. The energy shot with highest amount of caffeine content is shown in the table 3.

Additional amounts of caffeine can be added in energy drinks through additives such as Guarana, kola nut, Yerba mate and cocoa (Babu, Church, & Lewander, 2008;

Federal Institute for Risk Assessment, 2011; Heneman & Zidenberg-Cherr, 2011;

Reissig, Strain & Griffiths; 2009).

Factors affecting energy drink intake. The studies have shown that the common reasons for consumption of energy drink includes enhancing physical performance, overcoming fatigue, feeling energetic, to increase concentration, to remain

Table 2.

Caffeine content in the popular energy drinks

Energy Drink Caffeine Taurine Guarana Added Sugar

Brand Content (mg/ 8 oz ) (mg/ 8 oz) (g/ 8 oz)

(mg/ 8 oz)

Red Bull 77 1000 ND 27

Monster 86 1000 ND 25

Energy

Rockstar 80 ND ND 31

NOS 80 ND ND 27

AMP 74 7.5 156 30.6

Adapted from Caffeine Informer. (n.d). Caffeine Content of the Drinks. Retrieved from https://www.caffeineinformer.com/the-caffeine-database awake and for mixing with alcohol (Attila & Çakir, 2011; Ballistreri & Corradi-Webster,

2008; İşçioğlu, Ova, Duyar, & Köksal, 2010; Malinauskas, Aeby, Overton, Carpenter-

Aeby, & Barber-Heidal, 2007). By law, it does not require to enlist caffeine content from these active ingredients (Babu, Church & Lewander, 2008; Heneman & Zidenberg-Cherr,

2011). So because of this the actual caffeine in a single serving exceeds than the listed

amount of caffeine (Cannon, Cooke & McCarthy, 2001; Malinauskas, Aeby, Overton,

Carpenter-Aeby, & Barber-Heidal, 2007).

Table 3.

Top 10 energy shot brands with highest amount of caffeine

Energy Shot Brand Caffeine Content (mg/ fl. oz)

DynaPep 714.3

Tube shot energy drink 666.7

NRG Microshot 650.0

Liquid Caffeine 500.0

Energy Catalyst 434.8

Vital 4U Liquid Energy 310.0

Screamin Energy Max Vitamin 303.3

Kaffn8 Liquified Caffeine 300.0

Mix and Go 294.1

ALRI Hypershot 250.0

Adapted from Caffeine Informer. (n.d). Caffeine Content of the Drinks. Retrieved from https://www.caffeineinformer.com/the-caffeine-database

Consumption Data. The first energy drink was launched in the US in 1949, but it was after the launch of Red Bull in 1997, there was a drastic increase in market size of energy drinks. Initially athletes were the major consumers, however, as the market grew and expanded, the focus shifted from athletes to teenagers and young adults between 18 to 34 years old. The consumption of energy drink amounted to approximately 2.98 billion

US dollars in 2017 (“Statista”, n.d). Research has shown that females consume less energy drink than males. Half of the energy drink market consists of children (< 12 years old), adolescents (12-18 years old) and young adults (19-25 years old) (Babu, Church &

Leewander, 2008; Clauson, Shields, McQueen & Persad, 2008; Malinauskas, Aeby,

Overton, Carpenter-Aeby & Barber-Heidal, 2007). Males between the ages 18 and 34 year consume most energy drinks and one-third of teens between 12 to 17 years drink energy drink regularly (“National Center for Complementary and Integrative Health”, n.d). Also, the research has shown that young adults between the age 18 to 24 years old consumes 10.7 times more energy drink than the 60 and over age group (Park, Onufrak,

Blanck & Sherry, 2013). Other studies have also shown that 28% of 12 to 14 years old,

31% of 12 to 17 years old and 34% of 18 to 24 years old consumes energy drink regularly

(Oddy & O’Sullivan, 2009).

Sports Drink

The drinks that are consumed before or after exercise to prevent dehydration, supply carbohydrate, provide electrolytes and generally contains low amount of caffeine are termed as the sports drink (Coombes & Hamilton, 2000). The main goals of any sport drink are to provide: rapid gastric emptying rate, a body fluid balance, minerals that

typically last through sweat, and an adequate carbohydrate source to aid in energy supply and performance (Mitchell, Costill, Houmard, Flynn, Fink & Beltz, 1988; Seiple, Vivian,

Fox & Barteles, 1983).

Types. There are two main types of sports drink: carbohydrate-electrolyte sports drink and caffeinated sports drink (Coombes & Hamilton, 2000). On the basis of its goals, they can be classified as fluid replacers, carbohydrate loader, or nutrient supplements. Fluid replacing drinks are absorbed by the body as quickly as water and can be used in activities which is less than two hours. They can be consumed before, during, and after physical activity. Some of this drink contains glucose polymers which provide a faster gastric emptying rate and an energy source and because of this reason, they can fit into two categories- fluid replacing drink as well as carbohydrate loading drinks (Mitchell et. al., 1988). Carbohydrate loading drinks have carbohydrate loaders which produces more muscle glycogen for greater endurance and they can be used before and after ultra- endurance sports to increase muscle glycogen re-synthesis after exercise (Seiple et. al.,

1983). Nutrient supplement drinks are rich in vitamins and minerals and thus help to maintain a balanced diet. Athletes who want to lose weight can use these drinks to replace some of their food intake that is high in fat, and calories and in those who want to gain weight can take this drink with meals to increase caloric content. They can also be classified as isotonic, hypotonic or hypertonic on the basis of fluid, electrolyte and carbohydrate they have. Hypotonic sports drink have less amount of carbohydrate and more amount of salt and sugar than the human body and they are designed to rapidly replace the fluid lost during the exercise. Isotonic sports drink have similar amount of salt

and sugar as in the body fluid and they are designed to replace the fluid lost during exercise with increase in carbohydrate. Hypertonic sports drinks have a high amount of carbohydrate to provide maximum energy uptake (“British soft drinks”, n.d).

Components. Sports drinks mainly include carbohydrates, electrolytes and often caffeine as its main ingredients.

Carbohydrate. When the concentration of carbohydrate is low, the type of carbohydrate used does not have a major influence. Generally, the concentration of carbohydrate in sports drinks is between 6% and 15% (Coombes & Hamilton, Seiple et. al., 1983). Carbohydrates such as sucrose, glucose, fructose and/or glucose polymers

(maltodextrins) are used in sports drink (Smith, 1922). Polymers are more preferable to use than simple carbohydrates because they pass through the stomach more rapidly

(Seiple et. al., 1983). Simple carbohydrates provide energy and maintain fluid balance in the range of 5% to 10% carbohydrate concentration (Applegate, 1980; Murray, 1987).

Glucose polymers containing drinks increase the carbohydrate content up to 15% and increases the gastric emptying rate and they also minimize the osmolality by decreasing the effect on osmo-receptors (Seiple et. al., 1983). Among all the carbohydrates, fructose is absorbed more slowly than other carbohydrates and thus does not stimulate as much absorption of fluid (Coleman, 1988). Fructose does not play any role in increasing the performance because it cannot be metabolized and released rapidly by the liver to provide adequate amounts of glucose to the working muscle. Fructose, if used in high concentration, is not beneficial in fluid replacing drinks, but if used in carbohydrate

loading drinks, it can be used prior to an event to give the body time produce more glycogen (Coleman, 1988).

Electrolytes. Electrolytes are important to maintain the fluid balance in the body, to avoid dehydration and other damages such as hyperkalemia and hyponatremia, which can occur due to imbalance in electrolytes. Electrolytes are lost in urine and sweat. They play an important role in athletes, especially to maintain the hydration in the body. Sports drink generally has sodium, chloride, magnesium, calcium, and potassium (“American

Beverage Association”, 2016). Sodium maintains proper body fluid volume, improves water, and glucose absorption in the body. Sodium also plays an important role in muscle contraction and in the conduction of nerve impulses. Deficiency of sodium can cause nausea, vomiting, headache, loss of appetite, muscular weakness, and leg and abdominal cramps. Chloride regulates electrical potentials across cell membranes (Maughan &

Murray, 2000). Potassium plays an important role in muscle contraction, nerve impulse conduction, and also aids in storage and transport of glycogen across the cell membrane

(Maughan & Murrray, 2000). Magnesium assists in the formation of adenosine triphosphate (ATP) and regulates neuromuscular transmission, muscle contraction, and protein synthesis. Calcium plays an important role in the development of bone and teeth, muscular contractions, transmission of nerve impulses, blood clotting, and glycogen metabolism (Maughan & Murrray, 2000).

Other. Sports drink contains other ingredients such as citric acid to enhance the flavor, lactic acid as acidity regulator, potassium sorbate to inhibit the growth of microorganisms in the beverage, sodium bisulphite to preserve flavor, color, and prevent

bacteria from growing, caffeine to give feeling of alertness, ascorbic acid to be used as preservative because of its anti-oxidant properties and different colors such as sunset yellow (Maughan & Murrray, 2000.

Caffeine content. In comparison to energy drinks, caffeine is rarely used in a sports drink. There are very few caffeinated sport drinks in the market. Caffeinated sports drink is used only if the use of sports drink is rare, and used over the time during physical activity. Caffeine slows down the breakdown of glycogen and thus glucose production slows down, and because of this it takes longer time for glucose to reach to the muscles and thus lowers down the energy required during the physical activity (Cureton, Warren,

Millard-Stafford, Wingo, Trilk, & Buyckx, 2007).

Consumption Data. The sales of sports drink amounted to 999.7 million in US market. Americans drank about 4.7 gallons of sports drink per capita in 2015 (“Statista”, n.d).

Soft Drinks

The carbonated non-alcoholic and non-carbonated, non -alcoholic drink with added sugar as a main ingredient along with flavorings and colorings is considered as soft drink (soda drink), and also as sugar-sweetened beverage.

Types. Soft drinks can be classified on different types and by their packaging. On the basis of different types, they can be regular, diet (no natural sugar, a small amount of artificial sweetener), low-calorie, flavored, caffeinated, and caffeine free. By packaging they can be classified as bottled (glass or plastic), cans and soda fountain (“coca-cola

company”, n.d; “history of soft drinks”, n.d). The different types of soft drinks include colas, flavored water, carbonated water, seltzer, sweet iced tea, fruit drinks, carbonated soft drinks, diet soft drinks, and fruit juice.

Table 4.

Caffeine content in top selling caffeinated sports drink

Sports Drink Brand Caffeine Content

Rebound fx NA

Nuun 2.50 mg/ fl. oz

NOS active sports drink 10.04 mg/ fl. Oz

Jolt 10 mg/ fl. Oz

Rrunn (capsule) 30 mg/ capsule

Adapted from Caffeine Informer. (n.d). Caffeine Content of the Drinks. Retrieved from https://www.caffeineinformer.com/the-caffeine-database

Components. The main components in the soft drink consist of water, sugars and sweeteners, acidity regulators, carbon dioxide, flavorings, colorings, and preservatives.

Water. Regular soft drinks contain 90% water, whereas diet soft drinks contain up to 99% water. Softened water is used to prevent taste of chlorine residues (Ashurst,

Hargitt & Palmer, 2017).

Sugar and Sweeteners. Soft drinks uses sugars as well as sweeteners, generally regular soft drink uses sugars and diet soft drinks uses sweeteners. Soft drinks that use sugars contains between 1% and 12% sugar (w/w). Glucose, sucrose, or fructose

(generally as high fructose corn syrup) is used as natural carbohydrate sweeteners in their various forms. The most common sweeteners used are sucrose and high fructose corn syrup. Natural carbohydrate sweeteners are: sucrose, trehalose, isomaltulose and tagatose

(Ashurt, Hargitt & Palmer, 2017). Sucrose preserves and enhances the flavor of drinks, also gives a satisfying sensation. Trehalose is a disaccharide, and its relative sweetness is around 45% that of sucrose, and it is characterized by high thermos stability, and a wide pH stability range (Mortensen, 2006). Isomaltulose is also a disaccharide of glucose and fructose and it is tooth-friendly disaccharide with slow energy release, low glycemic index, and mild sweetness (Hausmann, 2009). Tagatose has the structure similar to fructose and it is as sweet as sucrose, and also have flavor-enhancing properties (Ashurst,

Hargitt & Palmer, 2017). The artificial sweeteners used are aspartame, acesulfame K, sucralose, and saccharin, among which the most used sweetener is aspartame, followed by saccharin. Generally aspartame is used alone, but sometimes it is used with saccharin.

Aspartame is an artificial sweetener that consists of L-phenylalanine and L-aspartic acid and it is 200 times sweeter than sucrose and it does not leave an unpleasant aftertaste. It is also unstable to heat, looses its sweetness when exposed to high heat for long period of time and thus can be added at the end of the cooking cycle. The soft drinks label should indicate phenylalaine because it can be harmful to individuals with a certain genetic disease, phenylketonuria (Fitch & Keim, 2012; Kregiel, 2015). The Acceptable Daily

Intake (ADI) for aspartame is 50 mg/ kg of body weight. Aspartame has four calories per gram, but as it is 200 times sweeter than sucrose, it is used in a lesser amount, so adding almost no calories to beverages. Acesulfame K is 200 times sweeter than sucrose and calorie free and it is thermostable, pH stable, and freely soluble in water. It is just used as sweetener and it is neither metabolized nor stored in the body and thus to be used in food and beverages (Fitch & Keim, 2012; Kregiel, 2015). ADI (Acceptable Daily Intake) for acesulfame K is 15mg/ kg. Sucralose is a sweetener derived from sucrose and it is 600 times sweeter than sucrose but indigestible thus contribute no calories and they are easily soluble in water and acid solutions and they are also thermostable and thus can be used in cooking and baking (Fitch & Keim, 2012; Saulo, 2005). ADI for sucralose is 5mg/kg.

Saccharin is 300 times sweeter than sucrose, calorie-free and thermostable but has a bitter/ metallic after taste and therefore, it is not used much (Fitch & Keim, 2012;

Mortensen, 2006; Stratford & James, 2003). ADI for saccharin is 15 mg/ kg of body weight. Some less common sweeteners include thaumatin and stevioside. Thaumatin is isolated from the katemfe fruit and is the most powerful natural sweetener, 2000 times sweeter than sugar and used in food as a safe sweetener and flavor modifier. Stevioside sweetener is 200 times sweeter than sucrose and it is extracted from the stevia plant

(Ashurst, Hargitt & Palmer, 2017; Mortensen, 2006).

Acid. Acid added to soft drinks improves taste by balancing the sweetness.

Human saliva pH is 6.8 which makes it almost neutral and so because of this the taste receptors interact with acids in food and drink and perceive it as sourness (Chaudhari &

Roper, 2010). The most commonly used acid regulator is citric acid, along with

preserving soft drinks, it also enhances the activity of beneficial antioxidants and adding aroma. Malic acid is used mostly in combination with citric acid and is used for strong flavor enhancement. Succinic acid is generally used in instant beverages to be prepared at home. Phosphoric acid has a strong effect on pH and is used to give a specific taste profile to cola-type beverages. But its use is controversial because it has adverse health effects such as high level of phosphorous in the blood (hyperphosphatemia), which causes organ damage mainly to kidneys and thus impairs its function (Kreigel, 2015).

Carbonation. Carbonation of soft drinks varies from 1.5 to 5 g/l. Carbonation makes drink acidic and this sharpens the flavor and taste and also helps in natural preservation of soft drinks (Korzeniewska, Filipkowska, Domeradzka, & Wlodkowski,

2005).

Flavorings and Colorings. Colorings are used for mainly three reasons: making the product more appealing, helping to correct for natural variations in color or changes occurring due to processing or storage and to contribute to maintain the qualities by which the drink is recognized. Flavorings are used in comparatively small amounts

(Gruenwald, 2009). Among the colorings, caramel color is the most used to give brown color to food and beverages worldwide. But it is reported that it contains carcinogenic agents termed as 4-methylimidazole (4-Mel), since FDA does not regulate its use, there is no transparency in mentioning the actual amount of caramel color used in any food or beverage (“consumerreports”, 2014).

Preservatives. Preservatives are used to improve the microbiological stability of soft drinks. The types of preservatives that can be used depends on the chemical and physical properties of both the preservative and the beverage and it also depends on the pH of the product, the presence of vitamins and the conditions of storage. Sorbates, benzoates and dimethyl decarbonate (DMDC) are safe to ingest preservatives and used in the soft drink (Kreigel, 2015), sorbates are effective against bacteria, yeasts, and molds.

Sorbates and benzoates are generally used in combination. Bensozates are used in carbonated, non-alcoholic, and juice beverages and they are readily soluble in water and works best at pH levels between 2 and 4.4 (Battey, Duffy & Schaffner, 2002). They are used to maintain the quality of beverages. Benzoates have carcinogenic effect, so they are rarely used in the soft drink industry now (“United States Environmental Agency

Protection”, 2012). DMDC is used generally in cold-sterilized soft drinks. They are very reactive and readily soluble in water based beverage. They have wide range of anti- microbial actions against yeasts, fungi, and bacteria. The maximum concentration of 250 mg/ L is recommended.

Caffeine Content. According to the Food and Drug Administration (FDA), the highest amount of caffeine in soft drink is 71 mg/ 8 oz and if it is more than that then it is considered as energy drink orsports drink. Table 5 shows the top 10 soft drinks in the market and table 6 focuses on the soft drink with highest amount of caffeine in the market.

Consumption Data. Soft drinks are the leading source of added sugars in US diet (Bray, Nielsen & Popkin, 2004). Energy intake from sugar-sweetened beverages has

increased by 135% in all age groups. It was seen that during 2011-2014, 62.9% of youth consumed at least one sugar- sweetened beverage. Higher percentage of consumption was seen in boys (64.5%) than girls (61.3%). It was seen that in 2015, 40.7 gallons of soft drink was consumed per capita in US.

Cocoa Drinks

Cocoa drinks are the beverages that are generally prepared by mixing cocoa powder with milk generally. Cocoa powder is obtained from the beans of plant

Theobroma cacao L., which belongs to Sterculiaceae family and it is a small, evergreen, four to eight meters tall tree with native to tropical region of America (Rusconi & Conti,

2010). Each seed contains 40-50% of fat as cocoa butter and polyphenols which makes up to 10% of the whole bean’s dry weight (Richelle, Tavazzi, Enslen & Offord, 1999;

Tomas-Barberán, Cienfuegos-Jovellanos, Marín, Muguerza, Gil-Izquierdo, Cerdá,... &

Pasamar, 2007).

Beans undergo the process of fermentation and drying, the walls of the pigment cells breakdown and the constituents of the beans are exposed. Fermentation of cacao beans is crucial for the development of chocolate flavor for the production of various chocolates as well as cocoa powder. Cocoa beans have a high concentration of polyphenols and this gives it extremely bitter flavor. Because of various manufacturing process such as fermentation and heating, the content of polyphenols can reduce to 10% in the final product. Polyphenol content can be affected by various sample origin, variety,

Table 5.

Top 10 best-selling soft drinks

Soft Drinks Caffeine (mg/ fl. oz)

Coca-cola 2.8

Diet coke 3.8

Pepsi-cola 3.2

Mountain dew 4.5

Dr. pepper 3.4

Sprite 0.0

Diet Pepsi 2.8

Diet Mountain Dew 4.5

Diet Dr Pepper 3.4

Fanta 0.0

Adapted from Caffeine Informer. (n.d). Caffeine Content of the Drinks. Retrieved from https://www.caffeineinformer.com/the-caffeine-database

Table 6.

Soft Drinks on the basis of caffeine content

Soft Drink Caffeine Content (mg/ fl. oz)

Jolt 10.00

Soda stream 10.00

Bawls Exxtra 9.4

Blink Energy Water 8.9

Flatt Cola 8.1

Afri Cola 7.4

Fritz Kola 7.4

Premium Cola 7.4

Hansen’s Diet Red 6.9

Bawls 6.4

Adapted from Caffeine Informer. (n.d). Caffeine Content of the Drinks. Retrieved from https://www.caffeineinformer.com/the-caffeine-database

degree of ripeness, climate, food processing (heating, fermentation) and food storage

(refrigeration practice). Three groups of polyphenols are present in the cocoa bean includes catechins, anthocyanins and proanthocyanidins. Because of fermentation, the polyphenols undergo various reactions such as epicatechin goes through oxidation and polymerization reactions to form complex tannins. The main catechin are epicatechins with up to 35% of polyphenol content. Dark chocolate with high cocoa content (>35%) has the richest polyphenol concentration within a group of cocoa derivatives. The concentration of theobromine in dry fat free cocoa is in the range of 2.4-3.2 grams/100g and caffeine between 0.3-1 grams/ 100g. Theobromine cacao is used to make chocolates and chocolate is the single most craved food (Spiller, 1998). Major sources include chocolate bars, hot cocoa mix, and chocolate milk (Weinberg & Bealer, 2001). Semisolid food prepared by grinding the cacao bean nibs and it is termed as chocolate liquor. Dark chocolate contains 15-50% of chocolate liquor, semisweet chocolate has at least 35% chocolate liquor and milk chocolate have 10-12% chocolate liquor. More the chocolate liquor, more the caffeine content in the product (Spiller, 1998).

The difference between cocoa and cacao occurs because of the processing ways.

Cacao is produced when the cacao beans are dried and fermented and heated at low temperatures. Heating them separates the fatty part of the bean from whole beans. Cacao is free from adding sugars, artificial sweeteners, and rich in anti-oxidants. To produce cocoa powder, the beans are harvested, fermented and the heated at higher temperatures and this results in slightly sweet flavor, and changes in the composition and they also have added sugars and sweeteners for marketing purpose.

In comparison to other caffeinated beverages, caffeine content of cocoa is much less accounting only for 6-10 mg/ 5 fl. oz. For cocoa beverages the caffeine in them also depends on the individual and how much cocoa do they add to their beverage. According to the USDA, 1 tbsp (5.4gram) of cocoa powder has 12 mg of caffeine. Hot cocoa; a beverage made by adding cocoa, sugar and/or chocolate syrup to hot milk has 5mg of caffeine/ 8 fl. oz. Hershey’s cocoa powder contains 8.4 mg of caffeine in 1 tbsp.

Caffeine and Health

Caffeine can be benficial or harmful, depending on the dose-dependent acute or chronic caffeine intake.

Cognitive Performance

For many years, caffeine has been used in various forms to enhance mental or cognitive functions (Snel & Lorist, 2011). Caffeine’s action is dose-dependent, low doses can improve cognitive performance such as attention, vigilance, and reaction time, reduces anxiety, whereas, high doses increases tension, symptoms of anxiety, nervousness, and jitteriness (Stafford, Rusted & Yeomans, 2007). There are various factors affecting caffeine’s effect on individual’s cognitive performance. Factors such as difficulty of task to be done (Diamond, 2005), difference in caffeine sensitivity (Renda,

Committeri, Zimarino, Di Nicola, Tatasciore, Ruggieri, ... & De Caterina, 2015), gender, body weight differences (Wood, Sage, Shuman, & Anagnostaras, 2014), motivational and emotional state of the individual (Diamond, Campbell, Park, Halonen, & Zoladz, 2007) and impulsivity, and sociability (Anderson, 1994). Research has shown that caffeine used

by individual to achieve a self-perceived, peak state of arousal, and eventually habitual intake of caffeine reaches to optimal level of cognitive performance (Yerkes-Dawson

Law) meaning that the caffeine in higher amounts will make no positive difference and will cause negative effects such as anxiety (Harvanko, Derbyshire, Schreiber & Grant,

2015). Caffeine affects the cognitive performance by affecting the nervous system by being the antagonist of adenosine receptors A1 and A2 and thus inhibiting its function.

This increases concentration of neurotransmitters in the Central Nervous System (CNS) and thus increases positive effects on vigilance, wakefulness, alertness, and memory

(Fredholm, 1995; Meeusen, Watson, Hasegawa, Roelands & Piacentini, 2006). Dosage of caffeine from 32 to 300 mg enhances cognitive performance and is beneficial than the higher doses of ≥ 400 mg (Lorist & Snel, 2008; McLellan, Caldwell & Lieberman, 2016;

Nehlig, 2010).

Sleep

Good sleep is required for overall good health in all age groups. It plays an important role in physical and mental health, accident prevention, and quality of life

(Wheaton, 2016; Danner & Phillips, 2008). Mammalian sleep cycle has two phases:

Quiet or Slow-wave sleep (SWS) and Rapid-Eye Movement (REM) or paradoxical sleep.

SWS has Electroencephalogram (EEG) with great coherence than EEG patterns of the awake state and REM has EEG which closely resembles desynchronized patterns of the awake state. During a good night sleep, adult human cycles between SWS and REM phases at ~90 minutes intervals, making total of four to six SWS-REM cycles (Steyn-

Ross, Steyn-Ross, Sleigh, Wilson, Gillies & Wright, 2005). Adenosine receptors are

found in the area of brain, which is involved in the regulation of sleep, arousal, and cognition (Riberio & Sebastiao, 2010). Landolt (2008b) has shown that the caffeine attenuates the buildup of sleep propensity associated with wakefulness and also attenuates EEG markers of non-REM (SWS) sleep homeostasis. Sleep disturbances by caffeine is different in each individual because of variation in sensitivity of caffeine, which is also based on age, genetics influence, and physiological response (Hollingworth,

1912; Yang, Palmer & deWit, 2010). Studies have shown that caffeine is associated with increase wake time after sleep onset (WASO), shorter sleep duration and longer daytime sleep (Berkey, Rockett & Colditz, 2008; Bryant Luddon & Wolfson, 2010; Drescher,

Goodwin, Silva & Quan, 2011; Lodato, Araujo, Barrus, Lopes, Agodi, Barchitta &

Ramos, 2013; Pollak & Bright, 2003; Roehrs & Roth, 2008). Moderate caffeine intake

(1-4 cups/ day) had a shorter sleep latency, fewer awakenings and better sleep than heavy consumers (8 cups/ day) who had sleep duration decreased by 40 minutes on average

(Mniszek, 1998; Sanchez-Ortuno, Moore, Taillard, Valtat, Leger, Bioulac & Philip,

2005). Adolescent studies have shown that caffeine intake in this group is mainly from soda intake and this contributes to daytime sleepiness (Bryant Ludden & Wolfson, 2010;

Orbeta, Overpeck, Ramchaaran, KPgan & Ledsky, 2006). In college students, caffeine intake of three to five cups per day is associated with habitual sleep duration of ≤ 6 hours per night (Pomeranz, Munsell & Harris, 2013). However, chronic use of caffeine may lead to fewer sleep-oriented complaints in users as their body gets used to the caffeine intake (Bonnet & Arnad, 1992). Also, it is difficult to know caffeine use due to daytime sleepiness or daytime sleepiness due to disrupted sleep which might be causes by caffeine

use. Caffeine may also be consumed to manage sleepiness during shift work or sleep disorder like narcolepsy (Åkerstedt, & Wright, 2009; Mitler, Walsleben, Sangal &

Hirshkowitz, 1998).

Sports

Caffeine has shown to enhance exercise performance over many years (Rivers &

Webber, 1907). Caffeine shows ergogenic effects on aerobic endurance (Burke, 2008), high-intensity exercise such as soccer and rugby (Gant & Foskett, 2010; Roberts, Stokes,

Trewartha, Doyle, Hogben & Thompson, 2010; Stuart, Hopkins, Cook & Cairns, 2005), muscular endurance (Da Silva, Messias, Zanchi, Gerlinger-Romero, Duncan &

Guimarães-Ferreira, 2015; Duncan, Stanley, Parkhouse, Cook & Smith, 2013), sprint performance (Grgic, 2018) and maximum strength (Grgic & Mikulic, 2017). For many years, caffeine has been used as a performance enhancement strategy for competition, but now focus has shifted to a method to support training goals (Graham, 2001). Athletes commonly use caffeine to offset fatigue caused with regular training (Doherty & Smith,

2005; Duncan & Oxford, 2011), to alleviate sleep disruption caused by early morning training sessions (Cook, Crewther, Kilduff, Drawer and Gaviglio, 2011), jet lag (Arendt,

2009), and may mask soreness caused by high training or competitive loads (Hurley,

Hatfield & Riebo, 2013; Maridakis, O’Connor, Dudley & McCully, 2007; Motl,

O’Connor & Dishman, 2003). There are various sources which contributes to total caffeine consumption in the athletes. These sources includes coffee being the most popular, caffeine-containing foods such as dark chocolate and medications, the caffeine- containing supplements which includes tablets, and energy drinks (Denoeud, Carretero-

Paulet, Dereeper, Droc, Guyot, Pietrella, ... & Aury, 2014). Exercise results in transient, muscle pain located in the activated musculature (Motl, O’Connor & Dishman, 2003).

Muscle adenosine concentration increases with increase in muscle contraction, however it is still under research that whether adenosine plays a role in perceptions naturally occurring in skeletal muscle pain during exercise or not (Salamone, Farrar, Font, Patel,

Schlar, Nunes, ... & Sager, 2009). There are various mechanisms which play role in caffeine-induced reduction in muscle pain during exercise. The hypoalgesia might occur due to caffeine’s action on adenosine receptors involved in the nociceptive system

(Sawynok & Liu, 2003). Alternatively, caffeine may indirectly affect the nociceptive system, for example, by altering muscle sensory processes (Sawynok & Liu, 2203).

Caffeine-habituated individuals require greater caffeine doses for it to works as an ergogenic aid as it modifies physiological and cognitive performance responses to acute caffeine doses and this can be hard to maintain in the athletes (Graham & Spriet, 1995).

Caffeine can improve the endurance performance when it is ingested at low-moderate dosages (3-6 mg/ kg body mass) and no further enhancement in performance was seen when it is consumed at higher doses ( ≥ 9 mg/kg) (Goldstein, Ziegenfuss, Kalman,

Kreider, Campbell, Wilborn, ... & Wildman, 2010). The effects of caffeine is dose- dependent. It can result in dizziness, headache, jitteriness, nervousness, insomnia, and gastrointestinal distress, usually at doses higher than 9 and 13 mg/kg for caffeine users and non-users respectively (Cornelis, Monda, Yu, Paynter, Azzato, Bennett, ... & Couper,

2011; Duncan, Stanley, Parkhouse, Cook, & Smith, 2013; Kendall, Moon, Fairman,

Spradley, Tai, Falcone, ... & Serrano, 2014).

Neurodegenerative Diseases

Caffeine acts as a stimulant and its effect on the nervous system has been known for years (Porciúncula, Sallaberry, Mioranzza, Botton, & Rosemberg, 2013). The chronic caffeine consumption decreases risk of developing neurodegenerative conditions such as

Alzheimer’s disease (AD) (Eskelinen, Ngandu, Tuomilehto, Soininen, & Kivipelto, 2009) and Parkinson’s Disease (PD) (Chen, Xu, Petzer, Staal, Xu, Beilstein, ... &

Schwarzschild, 2001; Chen, Lan, Roche, Liu, & Geiger, 2008; Postuma, Lang, Munhoz,

Charland, Pelletier, Moscovich, ... & Chuang, 2012). This shows that the caffeine’s relation to the lowering risk of developing the disease may be used in the treatment of neurodegenerative diseases (Joghataie, Roghani, Negahdar, & Hashemi, 2004; Maia, &

De Mendonça, 2002). Beneficial effects of caffeine on neurodegenerative disease approved to be involved in its role in activating or inhibiting adenosine receptors A1 and

A2 (Doré, Robertson, Errey, Ng, Hollenstein, Tehan ... & Tate, 2011; Snel & Lorist,

2011). In addition, caffeine has shown to reduce hyperalgesia, excitotoxicity, inflammatory response, dyskinesia, akinesia, sensory and motor deficits, and neuronal cell death linked to the pathophysiology of the neurodegenerative diseases (Schenone,

Brullo, Musumeci, Bruno, & Botta, 2010; Xiao, Cassin, Healy, Burdett, Chen, Fredholm,

& Schwarzschild, 2011).

Parkinson’s disease (PD) is a motor disability disease which occurs due to gradual break down of neurons, which leads to decrease in dopamine levels and this leads to abnormal brain activity. It can be genetic or due to environmental triggers. The dopamine and this clumps of cell have protein called alpha-synuclein, which is the major focus for

the study in the Parkinson’s disease (“Mayoclinic”, 2018; “Medlineplus”, 2018). The

“Dopamine Replacements” treatment has dominated the treatment of PD since early

1960s, there are some limitation to it which includes failure to alleviate the underlying dopaminergic neuron degeneration and thus gradual loss of drug effectS (Allain, Bentué-

Ferrer & Akwa, 2008) and, also has adverse effect such as dyskinesia (development of abnormal involuntary movements), psychosis, and behavioral disturbance (Ahlskog &

Mventer, 2001). Caffeine blocks the adenosine receptors, which may improve the motor activity (Camilo & Goldstein, 2004; Cunha & Agostinho, 2010) and delay the early onset of the disease (Chu, Chang, Black, Liu, Sompol, Chen, ...& Cheng, 2012) without having any adverse effects (Prediger, 2010). Caffeine also prevents the loss of dopaminergic neurons (Palacios, Gao, McCullough, Schwarzschild, Shah, Gapstur, & Ascherio, 2012), protects against disruptions of the blood-brain barrier (Prasanthi, Dasari, Marwarha,

Larson, Chen, Geiger, & Ghribi, 2010), reduces neuro-inflammatory responses, and nitric oxide production (responsible for excitotoxicity) (Cupino & Zabel, 2014; Salvemini, Kim

& Mollace, 2013).

Alzheimer’s disease is a progressive disease, which destroys memory, causes confusion and is a leading cause for dementia in aging population (Ashford, 2004;

Budson & Price, 2005). This disease is characterized by extensive accumulation of amyloid-β-peptide (Aβ) in the brain which triggers the cognitive decline in AD (Serrano-

Pozo, Frosch, Masliah & Hyman, 2011). Caffeine helps in treating AD by preventing the accumulation of Aβ and reverses cognitive impairment and decreases brain Aβ levels

(Chen & Chern, 2011; Yadav, Gupta, Srivastava, Srivastava & Singh, 2012).

It has been seen that moderate to high consumers are tolerant towards caffeine and, so only low or non-consumers can benefit from the acute caffeine administration

(Griffiths & Mumford, 1996). However, the cognition-enhancing properties associated with the neurodegenerative diseases are still under research (Einöther & Giesbrecht,

2013; Rogers, Heatherley, Mullings & Smith, 2013).

Bone Health

The epidemiological and metabolic intervention studies have shown through the analysis of relations hip between the caffeine intake and risk of osteoporosis and the effect of caffeine on calcium homeostasis that caffeine has potential to adversely affect the bone metabolism studies have shown that caffeine consumption of 150-300 mg

(equivalent 1.5-3 cups of coffee with average of 95 mg of caffeine per cup) after a 10 hour fast increases urinary calcium excretion for 2-3 hours in adolescent, young adults, and adults. (Bergman, Massey, Wise & Sherrard, 1990; Massey & Berg, 1985;

Hollingbery, 1988; Massey & Opryszek, 1990). This may occur due to caffeine induced hypercalciuria (increased level of calcium in the urine; more than 300 mg per day) or decreased intestinal calcium absorption (Bruce & Spiller, 1998; Ilich, Brownbill,

Tamborini & Crncevic-Orlic, 2002). A study by Harris and Dawson-Hughes (1994) have shown that when calcium intake is lower than 800 mg/ day and the dose of ingested caffeine is between 280-420 mg from brewed coffee (equivalent 3-4.5 cups of coffee with average of 95 mg of caffeine per cup), accelerated bone loss in healthy post-menopausal women. If the calcium intake level is adjusted, then the negative associations between caffeine intake and bone mineral density (BMD) disappeared, showing that adequate

intake of calcium can aide in reduced bone loss (Cooper, Atkinson, Wahner, O’Fallon,

Riggs, Judd & Melton III, 1992; Johansson, Mellstrӧm, Lerner & Ӧsterberg, 1992).

Postmenopausal women have decreased level of estrogen (sex hormone), which plays an important role in bone-remodelling, and thus its decrease causes bone fragality. So when there is low intake of calcium especially post-menopause, body obtains calcium from bone to maintain its extracellular calcium homeostatsis and decreases bone mineral density. When there is high intake of caffeine, there is more loss of the calcium and reduction in the bone mineral density (Golden & Abrams, 2014; Weitzmann & Pacifici,

2007). Coffee intake of more than four cups per day having more than 544 mg caffeine/ day was associated with high risk of hip fracture and decrease in bone mineral density of proximal femur in men than those who “almost never” consumed coffee (Hallström,

Melhus, Glynn, Lind, Syvӓnen & Michaëlsson, 2010; Hernandez-Avila, Colditzz,

Stampfer, Rosner, Speizer & Willet, 1991). CYP1A2 is responsible for the caffeine metabolism and breaking down caffeine into its metabolites with paraxanthine being the dominant metabolite. Studies have shown that the high activity of CYP1A2 metabolizes caffeine rapidly and thus increasing concentration of paraxanthine and making it responsible for harmful effects of coffee consumption on bone. This compound is a competitive antagonist for adenosine receptors which when deactivated can result in reduction of bone formation (Evans, Elfrod, Pexa, Francis, Hughes, Deussen & Ham,

2006; Hallstrӧm et al., 1994). Paraxanthine is also a potent suppressor of transforming growth factor beta which is responsible for bone formation (Evans et al., 2006; Fromigue,

Modrowski & Marie, 2004; Gressner, Lahme, Siluschek & Gressner, 2009). Caffeine’s

effect on the bone metabolism is hard to interpret because it is associated with other risk factors for osteoporosis such as lower calcium intake, increase in age, cigarette smoking and alcohol consumption (Barger-Lux, Heaney, Hayes, DeLuca, Johnson &Gong, 1995;

Barrett-Connor, Chang & Edelstein, 1994; Hernández-Avila et al., 1994). There are studies showing that caffeine may not be responsible for the decrease in calcium absorption or the urinary calcium excretion (Chen & Whitford, 1999; Conlisk & Galuska,

2000; Glajchen, Ismail, Epstein, Jowell & Fallon, 1988). So to be on safer side, untill there is any concrete evidence whether caffeine affects calcium status or not, it has been shown that the caffeine intake lower than 400 mg/ day with calcium intake of 800 mg calcium/ day do not have any major effect on bone status or calcium balance (Heaney,

2002; Nawrot et al., 2003).

Body Weight Management

Prevalence of obesity was over 36 percent in adults and 17 percent in youth during 2011-2014. Obesity is associated with high risk of chronic diseases (Ogden,

Carroll, Fryar & Flegal, 2015). Caffeine along with catechins in the green tea is associated with weight reduction. Weight regulation is all about energy balance, and caffeine has demonstrated its role in increasing metabolic rate, energy expenditure, lipid oxidation, lipolytic, and thermogenic activites; all these processes are favorable for weight management and may reduce the weight (Westerterp-Plantanga, Diepvens,

Joosen, Bérubé-Parent & Tremblay, 2006). Caffeine affects the thermogenesis by inhibiting enzyme phosphopdiesterase which is responsible for hydrolyzing c-AMP to

AMP. After the caffeine intake, c-AMP concentration increases, thus increasing

Sympathetic Nervous System (SNS) activity and hormone sensitive lipase (HSL), will be activated which promotes lipolysis. Besides activation of lipolysis, it also stimulated substrate cycles like the Cori-cycle and the Free Fatty Acid (FFA)-triglyceride cycle

(Westerterp-Plantenga, Lejeune & Kovacs, 2005; Westerterp-Plantanga, Diepvens,

Joosen, Bérubé-Parent & Tremblay, 2006). In Cori-cycle, lactate moves from the muscles to the liver and is converted to pyruvate which is then converted back to glucose in liver and transported to muscle via blood. Caffeine consumption of 300 mg per day for 24- hours, increased the energy expenditure to approximately 79 kcal per day, which is sufficient in maintaining weight (Temple, 2009).

Heart Health

Caffeine’s effect on heart health has been investigated in four main areas which includes cardiac arrhythmia, heart rate, serum cholesterol, and blood pressure (Nawrot et al., 2003). According to the studies, the intake of <450 mg caffeine per day does not increase the frequency or severity of cardiac arrhythmia in a healthy person or even with the person who has ischemic heart disease history. Studies have shown that there is an increase in systolic (5-15 mm Hg) and/ or diastolic (5-10mm Hg) blood pressure, most consistently at doses > 250 mg per day irrespective of sex, age, race, blood pressure status, or habitual caffeine intake (Greer, Kirby & Suls, 1996). Increase in blood pressure also causes slight decrease in heart rate and systemic release of epinephrine, norepinephrine, and renin (Robertson, Frolich, Carr, Watson, & Hollifield, 1978). At higher concentrations, caffeine induces intracellular calcium release, and phosphodiesterase inhibition and at the higher doses which are not typically consumed, it

can cause gamma-butyric acid inhibition (Fredholm et al., 1999). There are studies which show that not caffeine, but two diterpenoid alcohols; cafestol and kahweol, which are found at significant levels in boiled coffee, are hypercholestrolaemic components. These components are generally trapped by the use of paper filter by the largest amount in coffee preparation, so there is only a small increase in cholesterol level (Thelle, 1995).

This can be concluded positively because there is no significant association found between tea consumption and cardiovascular disease (Thelle, 1995). However, results from cohort study have shown that there is no association between caffeine and cardiovascular disease (Lopez-Garcia, van Dam, Willett, Rimm, Manson, Stampfer,

Rexrode & Hu, 2006). Thus, more study is required in this area.

Type 2 Diabetes Mellitus

Diabetes Mellitus is an autoinflammatory disease which is a collection of many disorders including hyperglycemia, dyslipidemia, insulin resistance, impaired β-cell functioning, and insulin secretion (Akash, Rehman& Chen, 2013; Akash, Shen, Rehman

& Chen, 2012; Akash, Rehman & Chen, 2013; Anjum, Zahra, Rehman, Alam, Parveen &

Akash, 2013). It was seen that several components of coffee were associated with lower risk of type 2 diabetes mellitus (T2DM). It includes effects of chlorogenic acid on glucose-6-phosphate, the antioxidant activity of polyphenols on α-glucosidase and effect of insulin on insulin secretion (Tuomilehto, Hu, Bidel, Lindström, & Jousilahti, 2004).

Epidemiological studies have shown that there is inverse relationship between coffee consumption and risk of T2DM, showing that long term coffee consumption may reduce the risk rather that short-term consumption (Huxley, Lee, Barzi, Timmermeister,

Czernichow, Perkovic,...& Woodward, 2009; Van Dam, & Hu, 2005). Short term doses of coffee decreased insulin sensitivity which may be due to caffeine-induced antagonism of adenosine receptors with increased epinephrine levels (Greer, Hudson, Ross, &

Graham, 2001; Keijzers, De Galan, Tack, & Smits, 2002; MacKenzie, Comi, Sluss,

Keisari, Manwar, Kim,… & Baron, 2007; Thong & Graham, 2002). Phenolic compounds present in the coffee, along with caffeine, are required to stimulate glucose uptake (Chu,

Chen, Black, Brown, Lyle, Liu, & Ou, 2011; Lee, Hudson, Kilpatrick, Graham & Ross,

2005; Li, Kim, Li, Liu, Liu, Himmeldirk, ...& Chen, 2005; Muthusamy, Anand,

Sangeetha, Sujatha, Arun, & Lakshmi, 2008; Prabhakar & Doble, 2009). However, it is still not clear if it is the coffee or caffeine which is associated with reducing risk of

T2DM, because there are various other components which play an important role in the various processes involved in T2DM ( Pereira, Parker & Folsom, 2006).

Liver Health

Caffeine, especially coffee consumption, is related with lowering risk of chronic liver disease with lower risk of elevation in the liver enzymes alanine aminotransferase

(ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), and alkaline phosphatase (ALP) (Heath, Brahmbhatt, Tahan, Ibdah &Tahan, 2017; Ruhl &

Everhart, 2005). Studies have also shown that there is an inverse relationship between caffeine drinking and the risk of hepatocellular carcinoma (Gallus, Bertuzzi, Tavani,

Bosetti, Negri, La Vecchia,...& Trichopoulos, 2002; Gelatti, Covolo, Franceschini, Pirali,

Tagger, Ribero, ... & Brescia 2005; Inoue, Yoshimi, Sobue, & Tsugane, 2005; Shimazu,

Tsubono, Kuriyama, Ohmori, Koizumi, Nishino, ... & Tsuji, 2005). One cup of coffee

consumed daily resulted in 15 percent reduction in risk of death from chronic liver disease and 4 cups daily consumption reduced risk by 77%, showing a dose-dependent response (Setiawan, Wilkens, Lu, Hernandez, Le Marchand, & Henderson, 2015). It has been seen that the coffee intake improved the serum concentrations of liver enzyme in patients with non-alcoholic fatty liver disease and with decreased liver fibrosis, both of them are responsible for chronic alterations leading to hepatic carcinoma (Saab, Mallam,

Coz & Tong, 2014). The mechanism which may be responsible for the hepato protection involved caffeine, phenolic compounds and melanoidins. The regulation of the production of connective tissue growth factor which is responsible for growth of cancerous cells ws reduced by caffeine, and this counteracts the hepatic fibrogenesis pathway (Saab, Mallam, Cox & Tong 2014). Phenolic compounds, caffeine and melanoidins also showed anti-oxidant effects that prevents free radical tissue damage by reducing reactive oxygen species. This oxygen species plays an important role in the inflammation process occurring in non-alcoholic fatty liver disease, steatohepatitics and liver fibrosis (Chen, Teoh, Chitturi & Farrell, 2014). However, there are studies showing that caffeine itself in the coffee may not be providing the beneficial effect (Honjo, Kono,

Coleman, Shinchi, Sakurai, Todoroki,...& Ogawa, 2001). There has been no relationship detected between the lower risk of liver disease and caffeinated beverages, thus more research is required in this area (Anty, Marjoux, Iannelli, Patouraux, Schneck,

Bonnafous,...& Mariné-Barjoan, 2012).

Reproduction

Studies have shown that once caffeine has entered the body, it can be easily distributed in the body and exists in the saliva, breast milk, embryo, semen and neonate

(Jensen, Henriksen, Hjollund, Scheike, Kolstad,... & Olsen, 1998; Ramlau-Hansen,

Thulstrup, Bonde, Olsen, & Bech, 2008). Being an adenosine receptor antagonist it may affect reproductive health (Wesselink, Wise, Rothman, Hahn, Mikkelsen, Mahalingaiah,

& Hatch, 2016). It has been reported that caffeine may decrease the fertility in both men and women (Watson, 2015). However, there is no consistent relationship between caffeine and sub-fecundity (Nawrot et al., 2003) and also that caffeine intake can increase the risk of any reproductive or perinatal adversity (Peck, Leviton & Cowan, 2010).

Studies have shown that caffeine can increase levels of c-AMP through inhibition of phosphodiesterase which may interfere with cell growth and development (Koren, 2000).

A fetus does not have developed and mature enzyme complex involved in the caffeine metabolism, so because of this there is increase in the half-life of caffeine in fetus. High amount of caffeine may affect the fetus and neonate and may have to suffer the consequences of potential adverse effects. As it is still under controversy, it is safe to limit caffeine intake for pregnant women and breastfeeding mothers by 200-300 mg/ day

(Peck, Leviton & Cowan, 2010). Higher doses than that may affect fetus development such as fetal intrauterine growth retardation or decrease in birth weight (Christian &

Brent, 2001; Dlugosz & Bracken, 1992; Nawrot et al., 2003; Olsen, Overvad & Frische,

1991; van Dam, 2008).

Dietary Habits of College Students

College students between the age of 18 and 24 years experience the transition phase of ascending from adolescence to young adulthood. This transition gives them a sense of freedom and major changes in the lifestyle (Franko, Cousineau, Trant, Green,

Rancourt, Thompson, ... & Ciccazzo, 2008) such as making their own food choices and developing physical activity patterns which can affect health status later in life (Vella-

Zarb & Elgar, 2009). It is a well established fact that dietary intake during young adulthood supports physical health, and affects the risk for chronic diseases (Hong,

Shepanski & Gaylis, 2016). Research, however, has shown that during this phase there is a tendency to engage in unhealthy dieting, meal skipping and fast food consumption and minimum physical activity (Franko et al., 2008; Vella-Zarb & Elgar, 2009). Lack of adequate physical activity and poor dietary habits often contribute to those who are overweight and obese and it is well researched that being obese and/or overweight are risk factors for many chronic diseases such as heart diseases, diabetes mellitus, and hypertension (Sherry, Blanck, Galuska, Pan, Dietz & Balluz, 2010).

Factors that affect the dietary habits of college students includes responsibility of purchasing and prepping their own meals, managing new eating schedules, and also the cost of healthy food (Cluskey & Grobe, 2009). Also, social and environmental factors such as limited access to healthy food and limited peer support for eating well can negatively affect the dietary habits of students (Driskell, Schake & Detter, 2008; Louis,

Davies, Smith, & Terry, 2007; Strong, Parks, Anderson, Winett & Davy, 2008). In addition to all these factors, stressors with new academic challenges are an important

ones. Stress is an important factor affecting the intake of food. Students experience psychological or physical reaction to stressors (Thoits, 1995). They adapt various coping mechanisms to deal with stress. Consumption of caffeinated beverages is one of the coping strategies (Lazarus, 1993; Thoits, 1995). Approximately, 400 kcal/ day is consumed from energy-yielding beverages, which accounts for ~20-25% of daily energy intake (Popkin, D’Anci, & Rosenberg, 2010). Chocolate and other cocoa-containing foods contributes to small amounts of caffeine, but the majority of caffeine comes from the beverage. (Frary, Johnston & Wang; 2005). Caffeine is associated with increasing alertness, improves memory, enhances mood, and decreases stress symptoms (Ríos,

Betancourt, Pagán, Fabián, Cruz, González, ...& Palacios, 2013). In food and beverages, caffeine is present in varying amounts either as naturally occurring compounds, as added constituents, or as both (Bailey, Saldanha, Gahche & Dwyer, 2014; Knight, Knight, &

Mitchell, 2006; Knight, Knight, Mitchell & Zepp, 2004; Mitchell et al., 2014; Somogyi,

2014).

Most dietary caffeine is consumed through beverages mainly from coffee of which consumption highly depends on the age (Mitchell et al., 2014). Coffee consumption is high in adults and young adults, while energy drink consumption is mostly high in teenagers and young adults (Mitchell et al., 2014). The consumption of carbonated sugar sweetened beverage (SSB), is high in young adults. These SSB’s also have caffeine as an important constituent (Heckman, 2010; Heckman, Sherry & De Mija,

2010; Kit, Fakhouri, Park, Nielsen & Ogden, 2013). Studies showed that soda was the principal source of caffeine for children and adolescents and in individuals older than 20

years, coffee is the major source of caffeine intake (Drewnowski & Rehm, 2016;

Mitchell, Knight, Hockenberry, Teplansky, & Hartman, 2014). Caffeine consumption through regular soda has declined in the young adults, but has increased through coffee, energy drinks and diet or low-calorie soda (Drewnowski & Rehm, 2015). Energy drinks are a relatively new source of caffeine and popular among college students (Emond,

Gilbert-Diamond, Tanski, & Sargent, 2014; Gallucci, Martin, & Morgan, 2016; Jeffers,

Vatalaro Hill & Benotsch, 2014; Norton, Lazev, & Sullivan, 2011). Energy drinks accounted for less than 9 percent of total caffeine consumed by young adults aged 18-24 years (Tran, Barraj, Bi, & Jack, 2016). U.S. college students consume most of their caffeine from coffee and tea. Average daily caffeine from energy drinks was seen to be

53.2 mg/ day for males and 30 mg/day for females. Soda is also a significant source of caffeine accounting for average 38.3 mg/day for males and 36 mg/day for females

(Mahoney, Giles, Marriott, Judelson, Glickman, Geiselman, & Lieberman, 2018).

CHAPTER III

METHODOLOGY

Research Design

The current investigation was a comparative, non-experimental, and retrospective study.

The research work employed pre-existing data obtained from undergraduate college students who enrolled in a basic sophomore level nutrition course at a public mid-western state university. The current work was a part of a large investigation which assessed the dietary intake and lifestyle of college students. Approval for analysis of pre-existing data was obtained from Kent State’s Institutional Review Board (IRB) after data collection was completed and students were assigned an identification number to keep their anonymity.

Data Collection

college were within this range. The exclusion criteria included ages younger than 18 years old and older than 24 years old, incomplete surveys, unrealistic diets such as diets with calorie intake less than 500 kcal or more than 5000 kcal, special diets such as weight loss or intermittent fasting.

Procedure

The class projects and homework were assigned and collected during the first two weeks of the semester, during which non-nutrition related subjects such as physiology of digestion and food safety were covered in class, in parliamentary procedure to ward off the influence of education of course materials on surveys and diet records.

On the first day of class, the primary researcher provided instructions on how to complete three-day dietary records and questionnaires. After completing the forms, students were expected to attend an interview session with research staff for validation of three-day dietary records. All data was collected by end of the second week of the semester.

Questionnaires. In the current study, the surveys which were of particular interest included demographic information, lifestyle, physical activity and caffeinated beverage consumption data.

The demographic questionnaire (appendix A) was made up of birth date, age, weight, and height information to be filled up along with other 23 questions which included (1) gender, (2) class standing, (3) major, (4) course load, (5) GPA, (6) if attended any other college level nutrition level course, (7) ethnicity, (8) car availability,

(9) mother’s highest education, (10) fathers highest education, (11) employment status,

(12) occupation, (13) family’s annual income, (14) individual’s monthly income, (15) health insurance, (16) blood cholesterol level, (17) yearly physical exam, (18) marital status, (19) children if any, (20) current living arrangements, (21) medical conditions,

(22) food restrictions due to medical conditions, (23) presence of food allergies.

Anthropometric Measurement. Before anthropometric measurement, research staff were required to attend a five-hour training session on how to perform measurements including the height, blood pressure, and waist-hip circumference and body composition. During the training session, they received verbal instructions with visual training materials including a power point presentation and videos. After that they practiced body measurements on one another to make themselves as accurate as they could. The same research members conducted specific measurements for each participant to insure accuracy. Students signed up for anthropometric assessment during the early mornings and were asked to not eat before two hours of measurement and were advised to wear light clothes.

After students arrived and had about three-minute resting time, blood pressure was measured three times and then averaged. If one of the values was 10% off from the other two measurements, it was eliminated from the calculation and only the other two numbers were averaged. Height was measured in a nearest tenth through the measuring rod of the Seca company and for accurate measurement of height, the participants were to stand aligned to the rod barefoot. The body mass index (BMI (kg/m2)), weight and body composition were measured by TANITA Bioelectrical Impedance Analysis (BIA) Body

Composition Analyzer TBF-410. The BIA machine has a weighing platform with anterior weighing platform electrodes and posterior weighing platform electrodes are wiped with an alcohol pad after each reading to keep the electrodes clean, so that accurate readings could be obtained as there won’t be any barrier in passing the current. For students’ comfort, waist- hip measurements were taken by two researchers of the same gender as the participants, only with the participant’s consent, and was measured in the closed area to ensure the privacy. For the hip measurement, the hip bone was identified, measuring tape was leveled with it and measured all the way around the body, and the number on the tape was noted. For the waist measurement measuring tape was leveled with belly button and measured all the way around the body, number on the tape was noted. While measuring, it was made sure that tape was not too tight and the student was in the relaxed position. The measurement was done by one person and the other person noted the number on the tape.

Four-day Dietary Record. The dietary intake information was obtained through a four-day dietary record including two weekdays and one weekend day. The students were instructed to adhere to their regular eating practices while they are recording their intake. The primary investigator gave the presentation explaining how to record the dietary log for all the four days to ensure the accuracy of student’s dietary records.

collected from on-campus dining places as well as restaurants which are common among the students. Students also were reminded to make note of if they had any drink with a particular meal and so on to make the whole process as accurate as possible. Food samples were collected and measured multiple times from locations that students commonly eat at, such as on-campus dining options, fast food chains and restaurants near campus. The standardization of common food items provides uniformity for dietary analysis.

Caffeinated Beverage Intake. Preliminary dietary analysis on 4-day dietary records which wereoriginally collected for the larger scale of study showed that Friday intake did not represent either weekday or weekend dietary intake. For this reason, only

3-day dietary intakes were used for the current investigation to capture 2 weekdays and 1 weekend day diet to represent typical intake over the week.

Data Analysis

For data analysis, Statistical Package for the Social Sciences (SPSS) version 25

(Armonk, NY, 2017) was used. Descriptive statistics were calculated for demographic information. Mean and standard deviations were calculated for the caffeine intake and the fluid consumption over a three-day period. An independent t-test was performed for caffeinated beverage intake between genders and showed no differences, therefore data was combined. An independent t-test was performed for added sugar, energy, and water intake between consumers and non-consumers to demonstrate if differences exist. A significance of p < 0.05 was set.

CHAPTER IV

JOURNAL ARTICLE

Introduction

”Chaudhari & Roper, 2008).

Caffeine affects human body systems including the nervous system, lipolysis process, the respiratory system, heart health, and cognitive function (Heckman, Weil &

Caffeinated beverages gained popularity in young population. Eighty-five percent of the college students reported consuming caffeinated beverages at least once in a day

(Mitchell, Knight, Hockenberry, Teplansky, & Hartman, 2014). For majority of them, coffee, tea and soda are the popular choices (Mahoney, Giles, Marriott, Judelson,

Glickman. Geiselman & Lieberman, 2018). The studies in the college students have shown that the caffeine consumption through soda has declined in the young adults, but

has increases through coffee, energy drinks and diet soda or low- calorie soda

(Drewnowski & Rehm, 2015). Even though the energy drinks do not make it into the three popular drinks, its popularity has been increasing with average caffeine intake from energy drinks with 53 mg/ day (Norton, Lazev & Suvillan, 2011). With the introduction of more caffeinated beverages such as energy drinks, energy shots and sports drink and also recent studies showing new developments in the field of caffeine and health effects, it is important to study their intake in college students as this phase of life plays an important role in the development of long-term habits and lifestyle (Kvaavik, Anderson

& Klepp, 2005).

The purpose of this study was to evaluate the consumption pattern of caffeinated beverages in the undergraduate students at a public mid-western university. The study hypothesized i. sugar intake will be higher in consumers than non-cosnumers. ii. Water consumption will be high in consumers than non-consumers. iii. Total energy intake will be more in consumers than the non-consumers.

Methodology

In this study, the data was collected from 234 undegraduate students at a public mid-western university.

Research Design

The current investigation was a comparative, non-experimental, and retrospective study. The research work employed pre-existing data obtained from undergraduate college students who enrolled in a basic sophomore level nutrition course at a public mid-

western state university. The current work was a part of a large investigation which assessed the dietary intake and lifestyle of college students. Approval for analysis of pre- existing data was obtained from Kent State’s Institutional Review Board (IRB) after data collection was completed and students were assigned an identification number to keep their anonymity.

Data Collection

Data was collected from class projects and homework assignments of 234 students who were enrolled in the course NUTR 23511 “Science of Human Nutrition” during the spring semester of 2017 from all majors. The data from students within the range of 18 to 24 years are considered for the study as large part of the students in the college were within this range. The exclusion criteria included ages younger than 18 years old and older than 24 years old, incomplete surveys, unrealistic diets such as diets with calorie intake less than 500 kcal or more than 5000 kcal, special diets such as weight loss or intermittent fasting.

Procedure

On the first day of class, the primary researcher provided instructions on how to complete three-day dietary records and questionnaires. After completing the forms,

students were expected to attend an interview session with research staff for validation of three-day dietary records. All data was collected by end of the second week of the semester.

Questionnaires. In the current study, the surveys which were of particular interest included demographic information, lifestyle, physical activity and caffeinated beverage consumption data.

(9) mother’s highest education, (10) fathers highest education, (11) employment status,

(22) food restrictions due to medical conditions, (23) presence of food allergies.

could. The same research members conducted specific measurements for each participant to insure accuracy. Students signed up for anthropometric assessment during the early mornings and were asked to not eat before two hours of measurement and were advised to wear light clothes.

After students arrived and had about three-minute resting time, blood pressure was measured three times and then averaged. If one of the values was 10% off from the other two measurements, it was eliminated from the calculation and only the other two numbers were averaged. Height was measured in a nearest tenth through the measuring rod of the Seca Company and for accurate measurement of height, the participants were to stand aligned to the rod barefoot. The body mass index (BMI (kg/m2)), weight and body composition were measured by TANITA Bioelectrical Impedance Analysis (BIA)

Body Composition Analyzer TBF-410. The BIA machine has a weighing platform with anterior weighing platform electrodes and posterior weighing platform electrodes are wiped with an alcohol pad after each reading to keep the electrodes clean, so that accurate readings could be obtained as there won’t be any barrier in passing the current. For students’ comfort, waist- hip measurements were taken by two researchers of the same gender as the participants, only with the participant’s consent, and was measured in the closed area to ensure the privacy. For the hip measurement, the hip bone was identified, measuring tape was leveled with it and measured all the way around the body, and the number on the tape was noted. For the waist measurement measuring tape was leveled with belly button and measured all the way around the body, number on the tape was noted. While measuring, it was made sure that tape was not too tight and the student was

in the relaxed position. The measurement was done by one person and the other person noted the number on the tape.

After completion of the dietary record form, each student was scheduled for an interview to have information on the log verified. During the interview session, research staff examined the food records and used food models and measuring cups/ spoons to more accurately adjust to actual intake. For the beverages, actual cups of different sizes were collected from on-campus dining places as well as restaurants which are common among the students. Students also were reminded to make note of if they had any drink with a particular meal and so on to make the whole process as accurate as possible. Food samples were collected and measured multiple times from locations that students commonly eat at, such as on-campus dining options, fast food chains and restaurants near campus. The standardization of common food items provides uniformity for dietary analysis.

3-day dietary intakes were used for the current investigation to capture 2 weekdays and 1 weekend day diet to represent typical intake over the week.

Data Analysis

For data analysis, Statistical Package for the Social Sciences (SPSS) version 25

Results

From the original data collected from 250 students who were enrolled in the

Science of Human Nutrition classes, 233 files were used in final analysis after elimination procedure per exclusion criteria. The mean age (years) of the students was 19

± 1.88 and mean BMI (kg/m2) was 25.7 ± 5.71. Table 7 shows the demographic characteristics of the participants. The majority was Caucasian, followed by Black/

African American. About half of the participants were freshman followed by sophomores, juniors, and seniors in that order.

Analysis reported a total of 25.19 ± 31.95 fluid ounces consumption of caffeinated beverages with mean intake of 130 mg caffeine from all the caffeinated

beverages. Table 8 illustrates the average intake of caffeinated beverages (fl. oz) and caffeine intake (mg) in college students enrolled in the Science of Human Nutrition class.

Table 7.

General characteristics of college students enrolled in the Science of Human Nutrition classes

n % Gender Male 69 28.1 Female 164 71.9 Ethnicity White 178 78.4 Black/African American 26 11.5 Hispanic/ Latino 7 3.1 Asian/ Pacific Islander 5 2.2 Middle Eastern 4 1.8 Other 7 3.1 Class standing Freshman 126 55.3 Sophomore 61 26.8 Junior 26 11.4 Senior 15 6.6

The independent t-test for caffeinated beverages and water intake showed no significant difference between genders, so both the groups were combined for the data

analysis. The most popular caffeinated beverage was coffee, with 27.5% of the students consuming coffee at least once during the three-day period, which was followed by soda in the current participants.

Table 8.

Three-day average intake of caffeinated beverages (fl. oz) and caffeine (mg) from caffeinated beverages in college students (n=233) enrolled in the Science of Human

Nutrition classes

Fluid ounces (fl. oz) Caffeine Intake (mg) mean SD mean SD Coffee 7.18 14.50 86.21 174.07 Tea 5.61 13.79 16.86 41.39 Soda 6.44 17.21 12.89 34.43 Sports drink 4.42 12.05 11.07 30.14 Cocoa drink 0.88 3.80 0.88 3.80 Energy drink 0.10 0.99 1.05 9.91 Other 0.52 3.44 1.58 10.33 Total 25.19 31.95 130.55 193.40

Table 9 displays per capita consumption of fluid ounces of caffeinated beverages and caffeine intake from caffeinated beverages. One-third of students were the coffee consumers followed by tea (n=48) and soda (n=48).

The result of independent t-test on sugar consumption from all the sources between consumers and non-consumers showed that sugar intake was significantly higher in consumers 82.37 ± 41.46 gram compared to non-consumers whose average intake was

59.7 ± 82.37 gram (p < .001). Out of 82.37 gram of total sugar, 72.11 gram was from caffeinated beverages in the consumers, accounting for almost 82% of total sugar consumption. There was no difference found in the average total kcal intake between consumers and non-consumers; 2095.03 ± 644.73 kcal in the consumers and 1903 ±

801.155 kcal in the non-consumers (p = 0.057). Average water intake in the study population was 152.84 ± 18.46 fluid ounces. The result of t-test indicate that non- consumers’ drank more water (188.59 ± 139.107 fluid ounces) than consumers (128.23 ±

114.78 fluid ounces) (p = 0.001).

Table 9.

Per capita fluid ounce (fl. oz) and caffeine intake (mg) over the three-day period in college students enrolled in the Science of Human

Nutrition Classes (n=233)

Fluid ounces (fl. oz) Caffeine intake (mg)

mean SD mean SD

Coffee

Male (n=12) 32.80 26.01 393.70 312.23

Female (n=52) 24.62 13.25 295.47 159.02

Total (n=64) 26.15 16.45 313.89 197.45

Tea

Male (n=11) 26.63 14.70 79.89 44.11

Female (n=37) 27.47 19.46 82.40 58.39

Total (n=48) 27.27 18.34 81.83 55.02

Soda

Male (n=18) 37.68 32.04 75.37 64.09

Female (n=30) 27.44 20.99 54.89 41.98

Total (n=48) 31.82 25.85 62.57 51.71

Sports drinks

Male (n=9) 41.77 17.78 104.44 44.47

Female (n=28) 23.42 13.19 58.56 32.98

Total (n=37) 27.89 16.26 69.72 40.66

Cocoa drinks

Male (n=6) 16.60 8.88 16.60 8.88

Female (n=10) 10.60 6.39 10.60 6.39

Total (n=16) 12.85 7.73 12.85 7.73

Energy drinks

Male (n=1) 8.40 - 84.00 -

Female (n=2) 8.00 5.65 80.00 56.56

Total (n=3) 8.13 4.00 81.33 40.06

Other caffeinated beverages

Female (n=6) 20.50 7.68 61.50 23.06

Total (n=7) 20.50 7.68 61.50 23.06

Discussion

The primary purpose of this study is to examine the caffeinated beverage consumption among undergraduate students enrolled in the Science of Human Nutrition classes in Spring 2017 at a public mid-western university.

Characteristics of Study Population

In the current study using nutrition classes, more than half of the individuals were female (~ 70%) while the typical gender ratio of university is 63 to 37 for female to male.

This is not an unexpected result because there are more females than males in health- related field (Hill, Corbett & St Rose, 2010).

Top Choice of Caffeinated Beverages

The current investigation revealed about little more than half of students in classes consumed caffeinated beverages over a three-day period. Among them, one-third drank at least one caffeinated beverage per day. Although studies that investigated caffeinated beverage consumption in college students are not readily available, one study which studied a beverage intake pattern in different age groups reported that 85% of the college students between 18-24 years consumed caffeinated beverages. (Mitchell et al., 2014).

This discrepancy between the two studies may be partially due to the small sample size of the current investigation. Another possible reason is that the data for this study was collected in the beginning of the semester, when students might not be under much stress or may not have to stay up late to prepare for exams and assignments with help of caffeine. Although the proportion of students who consumed caffeinated beverages were relatively low in the current study, the amount of per capita consumption of caffeinated

beverages were similar (25.19 fl. oz.) to the result reported by Mitchell et al. which was

25 fl. oz (2014)

The current investigation showed that the top three choices of caffeinated beverages among college students were coffee (n=64), soda (n=48), and tea (n=48). This pattern is similar to the caffeinated beverage intake trend in general population (Mahoney et al., 2018; Mitchell et al., 2014). In this study, even though equal numbers of students reported to drink soda and teas, and there are similar amounts of caffeine in both beverages, the result showed that caffeine consumption was higher from tea than from soda.

Coffee. Coffee intake was showed no significant difference between gender, which is in accordance with the finding by Mahoney et al. who reported there were no differences in coffee intake between males and females (2018). In the current study, female’s first choice was coffee. The numerous studies have shown that coffee intake aids in body weight management, which can be a possible reason why coffee ranked as a top choice of caffeinated beverages among females, as they are more interested in body weight management than the males (Diepvens, Westerterp & Westerterp-Plantenga,

2007; Lowery, Kurpius, Befort, Blanks, Sollenberger, Nicpon & Huser; 2005).

Soda. An average consumption of soda in the current study population was 6.4 fl. oz per day which is a little less than 8 fl. oz of soda intake reported by Mitchell et al.

(2014). This difference may be due to sample size or collection time of two studies. In addition, it may reflect a steady decrease in soda consumption in general population since

2010 (“Statista”, 2017). This research, however, showed that soda was still the second choice of the drinks among this study population. Soda may be popular in this population because they can get it everywhere at cheaper price than other drinks such as juice or milk. Vending machines can be found in various places throughout campus and free- refills are available in most restaurants around campus. It also has been reported that some people choose soda over other beverages because it tastes better than other drinks

(Block, Gillam, Linakis & Goldman, 2013). Soda consumption also is partly attributed to aggressive commercial promotion which spends billions of dollars on marketing sodas

(Koordeman, Anschutz, van Baaren & Engels, 2010; Welsh, Lundeen, & Stein, 2013).

Tea. In this study, tea was third choice, which was similar to others’ findings

(Mahoney et al., 2018). The average intake of tea in the current investigation was 5.61 fl. oz which is lower than 7 fl. oz as reported in the study by Mitchell et al. (2014). The lower intake of tea in the males can be due to the American cultural notion of men not drinking tea; in comparison, the British and Asian studies have shown that the tea intake was high in both males and females, as tea is an important part of their culture (Grigg,

2002; Iso, 2005; Pitelka, 2013). Even though the tea consumption is comparatively lower in current study and other investigations too, over the years there has been increase in the tea consumption in Americans. This can be due to the heatlh benefits of different compounds found in the tea other than the caffeine (Fredman, 2014; Hayat, Iqbal, Malik,

Bilal & Mushtaq, 2015).

Energy drinks. Energy drinks are a large part of the beverage industry and their share of the market is still increasing, especially among the young population. One of the

unexpected findings in this investigation was that energy drink consumption was very low; only three students reported consuming it. Per capita consumption of energy drink was 8.13 fl. oz which was lower than the intake of energy drinks reported by other researchers (Malinauskas et al., 2007). The previous studies have shown a high intake of energy drinks in college students, with almost 50% drinking from one to four 8 fluid ounce can per day, which contradicts with the current study, which reports only 1.28% of the students as having an average of 0.1 fluid ounces per day. Since the current study was conducted early in the semester, the consumption might have been low. It has been reported that energy drink intake increased as the exam approaches or the workload increases, as the energy drinks are believed to increase wakefulness, mental clarity, reaction time and focus attention (Bichler, Swenson & Harris, 2006; Malinauskas et al.,

2007). This may explain why the current population has lower intake as the data was collected earlier in the semester (second week) when usually there is not much academic pressure. If consumed in large volume, energy drinks have a wide spectrum of negative effects such as insufficient sleep, heart palpitations, and acute and chronic daily headaches (Alsunni, 2015). There are cases in which high consumption of energy drinks has proven to be lethal. A 25-year old man was presented to the emergency department with substernal chest pain, shortness of breath, nausea, and vomiting. The investigation in his case showed the reason for his symptoms was the consumption of seven to nine cans of caffeinated energy drinks per day for a week. Another study reported a young woman suffering from myocardial infarction due to 20 grams of caffeine from the energy drinks.

In 2009, a young man suffered from cardiac arrest due to excessive amounts of

caffeinated beverages in a day (Ullah, Lakhani, Siddiq, Handa, Kahlon & Siddiqui,

2018). This warns the danger of energy drinks in high amount of more than three to four cans of caffeinated energy drinks can have lethal effects.

Sports drinks. A relatively unknown fact about sports drinks that many people are not aware about is that many of them contain caffeine. The caffeine in the sports drinks contradicts the primary purpose of sports drinks: to keep the body hydrated, during the normal day activities or while doing the physical activity. In the current study, females consumed more sports drinks (12%) than the males (4%), which is different than the study by Larson, Laska, Story & Neumark-Sztainer (2015), in which they compared sports and energy drinks separately and reported that males had more sports drinks

(44.6%) than females (19.9%). Although coffee provides some benefits such as increasing endurance, offset fatigue and aids in muscle contraction to atheletes increasing performance, effect of caffeine during the physical activity is dose-dependent. The habitual caffeine intake will require more caffeine to get benefits from it during the physical activity Goldstein et al., 2010). High amount of caffeine for the non-habitual users can cause the negative effects in the individuals. (Cornelis et al., 2011; Duncan et al., 2013; Kendall et al., 2014).

Caffeine Intake from Caffeinated Beverages

Although caffeine has some positive physiological benefits such as alertness, cognitive vigilance, and as an ergogenic aid in athletes (Heckman, Weil & DeMeija,

2010; Nawrot, Jordan, Eastwood, Rotstein, Hugenholtz, & Feeley, 2003). The recent studies have shown that caffeine can play a role in treating neurodegenerative diseases

such as Alzheimer’s and Parkinson’s (Postuma, Lang, Munhoz, Charland, Pelletier,

Moscovich, ... & Chuang, 2012). High intake of caffeine can cause serious chronic effects on heart health, bone health, fertility in women, and respiration (Schellack, 2012).

Therefore, to avoid undesirable side effects, caffeine consumption should be limited to ≤

400 mg per day from all the sources, as suggested by the FDA. The current intake of caffeine in the general U.S. population is 165 mg/ day (Mitchell et al., 2014).

The average intake of caffeine in the current investigation was 130.55 mg/ day while caffeine consumption estimated from the other study was 122 mg/ day (Mitchell et al., 2014). Although this amount is within recommended intake of caffeine, it should be noted that there are various sources of caffeine besides caffeinated beverages; chocolates, chocolate milk, dietary supplements, caffeine pills, and certain medications (Andrews,

Schweitzer, Zhao, Holden, Roseland, Brandt,…, Yetley, 2007; Heckman & Gonzalez de

Mejia, 2010). Caffeine consumption was highest from coffee, with an average of 86.21 ±

174.07 mg per day, followed by tea and soda. Caffeine intake from coffee was a little higher compared to the result from Mitchel et al. (2014), which reported 60 mg of caffeine intake from coffee in the college population.

Sugar Intake

Sugar is another important component in the caffeinated beverages after caffeine.

Soft and sugar-sweetened beverages (SSB) are major sources of added sugars in the diets of U.S. residents (Welsh, Sharma, Grellinger & Vos, 2011). The soft drinks contribute to the empty kcal in the diet, meaning they don’t provide any nutrients. The studies have shown soft drink consumption is associated with high energy intake, greater body weight,

and poor nutrition because of its sugar content (Tordoff & Alleva, 1990; Vartanian,

Schwartz & Brownell, 2007). In addition, high fructose corn syrup (HFCS) is used commonly in the beverage industry (Johnson, Appel, Brands, Howard, Lefevre,

Lustig,….Wylie-Rosett, 2009). High fructose corn syrup, composed of either 42% or

55% fructose, is similar in composition to table sugar (Coulston & Johnson, 2002).

Studies also suggest excessive fructose consumption increases epidemics of insulin resistance, obesity, hypertension, dyslipidemia, and type 2 diabetes mellitus (Dhingra,

Sullivan, Jacques, Wang, Fox, Meigs, D’Agostino, Gaziano & Vasan, 2007; Elliott,

Keim, Stern, Teff & Havel, 2002; Gross, Li, Ford & Liu, 2004; Havel, 2005; Lé &

Tappy, 2006).

Although there is no specific recommendation available for the intake of added sugar, the Dietary Guidelines for Americans sets limits to 10% of total caloric intake.

(Erickson, Sadeghirad, Lytvyn, Slavin & Johnston, 2017). In the U.S diet, however, beverages contribute to 21% of total calories in the diet (Nielsen & Popkin, 2004).

In the current investigation, consumers in the current study had 82.37 grams of total added sugar, of which 72.11 grams were from caffeinated beverages indicating most of sugar intake was from caffeinated beverage intake. In addition, among the consumers,

15.7% of total kcal was from sugar and 14% of their total intake of calories was from added sugar from the caffeinated beverages. As per the recommendation of 10% calorie from added sugar in the diet by Dietary Guidelines for Americans, the current population is consuming 14% of the total kcal from the added sugar from caffeinated beverages

which is much higher than the guidelines. These results imply that added simple sugar intake can be reduced by decreasing caffeinated beverage consumption.

Water and Dehydration

Water is required for all biological processes and for the growth of the human body, making it important to maintain hydration status (Lang & Waldegger, 1997;

Popkin, D’Anci & Rosenberg, 2010). Dehydration can cause fatigue, confusion, dry mouth, extreme thirst, and loss of mobility, making it important for the consumers in the current population to increase their water intake (Popkin, D’Anci & Rosenberg, 2010).

The adequate intake for men and women is 3.7 L and 2.7 L per day, respectively (Sawka,

Cheuvront, & Carter, 2005). Caffeine is a diuretic and it can cause dehydration even within the safe limits, making it important to drink enough water with caffeine intake

(Alsunni, 2015).

In the current study caffeinated beverage consumers drank 128.23 fluid ounces

(3.79 L) of water per day while non-consumers drank 188.59 (5.5 L) fluid ounces per day. Interesting finding was that both consumers and non-consumers had higher water intake compared to the result from a similar study that was performed by the same investivators in the past (Drewnowski, Rehm & Constant, 2013). There are a couple of reasons that possibly explain why students increase water intake. Over the years, the college students might have agained knowledge about the importance of water intake from various sources including school education and media and made water a part of the diet. In addition, there are various apps available that remind people to drink water at specific intervals. This also might have encouraged college students, who are heavy users

of mobile apps, to increase water intake (Goldstein, Ziegenfuss, Kalman, Kreider,

Campbell, Wilborn, ... & Wildman, 2010).

Limitation

The fact that the data was collected through the dietary log; the students keeping track of their own diet for the study period can affect the study to some extent. It has been seen that the individuals sometimes tend to change their diet because they become aware that their diet is going to be analyzed. Also, the ability to report the portion size varies from person to person. The added total sugar data was collected form the ESHA software.

Hand calculated added sugar for the caffeinated beverages showed high values, whereas the total added sugar reported by the software by low in reference to the added sugar from caffeinated beverages which should be much higher. So, the software might be under analyzing the total added sugar and the actual total added sugar is higher than what is reported. This problem is something that software companies can work on to make their analysis software more accurate.

Another limitation is the time of the study being conducted. The study was conducted during the second week of the semester, which can affect the intake the intake of several drinks such as energy drink and coffee; which are known to be consumed more to stay more vigilant and more focused, which can be required as the semester goes on and exams approache. One more limitation is the calculation of the caffeine content in the energy drinks, as it has many other components other than caffeine, which have caffeine content in them, but according the FDA, they are not legally required to be report the

caffeine from all those sources so this lack od enforcement can affect the actual caffeine content in the energy drinks. It is also important to note that the caffeine content of beverages we used for the calculations are averages and may differ between brand types of the same product.

Conclusion

This study is one of the very few studies which focuses on the consumption of caffeinated beverages in U.S. undergraduate students. The pattern here showed was that the coffee, soda, and tea were the top three choice in the population, with the very low consumption of sports drinks, energy drinks and cocoa drinks. The caffeine intake in the consumers was reported 220.42 mg/ day, which is within the safe limits suggested by the

FDA (400 mg / day). Although the water intake in both the groups was significantly different, and when compared with the recommanded values the water intake was in accordance with recommended intake in both groups. The consumers had their majority of the total added sugar from the sugar in caffeinated beverages, suggesting that added sugar ifrom the caffeinated beverages contributes approximately 14% of the total energy intake. The high intake of added sugar has adverse effects, caffeine having its own advantages and disadvantages and both the components being an important part of young adults’ diet, suggests that more research and understanding about those components is required.

APPENDICES

APPENDIX A. DEMOGRAPHIC QUESTIONNAIRE

100

APPENDIX B. CAFFEINATED BEVERAGE INTAKE DATA SHEET

102

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