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E S U ProteinsM and O O AminoG R N S I S N A R L A C E R L O E E G L A A G S N E R O C F F T O O Y N T ± R E Y P L Nutrition OScoreboardN O R TRUE FALSE 1 The primary functionP of is to provide energy. W 2 “Nonessential amino Eacids” are not required for nor- mal body processes.I Only “essential amino acids” are. 3 High-protein dietsV enhance muscle development in individuals whoE work out a lot. R R O on next page Answers F Brown_U15_1-12.qxd 5/21/04 11:23 AM Page 2

E S U Answers to Nutrition Scoreboard [ KEY CONCEPTS AND FACTS ] M TRUE FALSE 1 Energy is a function of protein, but it’s not theO ✔ • are made of amino • Protein tissue construc- primary one. acids. Some amino acids are tion in the body proceeds O “essential” (required in the only when all nine essen- 2 “Nonessential amino acids” Gare requiredR by the body, ✔ ), and some are tial amino acids are but they are not requiredN componentsS of our diet. “nonessential” (not a available. (Yes, it is confusing.) I S required part of diets). • Appropriate combinations N A • Although protein can be of plant can supply 3 Muscles contain protein, but you can’t increase ✔ used for energy, its major sufficient quantities of all muscle mass byR consumingL a high-protein diet— functions in the body the essential amino acids. whether you’reA a couch Cpotato or a nationally involve the construction, ranked athlete.E maintenance, and repair of R protein tissues. L O E E G L A Protein’s Image versusA Reality G S The term protein is Nderived Rfrom the Greek word protos, meaning “first.” The der- ivation indicates theE importance ascribed to this substance when it was first recog- protein nized. An essential structuralO component of all living matter, protein is involved in almost every biologicalC process in the . Protein has a very positive image Chemical substance in foods F (Illustration 15.1). It’s so positive that you don’t have to talk about the importance made up of chains of amino F of protein—people Tare already convinced of it. acids. O Rich or poor,O nearly all people in the United States get enough protein in their diets.Y Actually, most people consume more protein than they need. Average intakes of protein exceed N the Recommended Dietary Allowance (RDA) level for all age and sexT groups.± Approximately 15% of total calories in the average U.S. adult diet are Rsupplied by protein. E High-proteinY intakes are generally accompanied by high- and low-fiber intakes.L That’s because foods high in protein such as hamburger, cheese, nuts, and P eggs are high in fat and contain little or no fiber. Even lean provide a consid- Illustration 15.1 O erableN proportion of their total calories as fat (Illustration 15.2). The protein perception.R O Protein P Functions of Protein W Proteins perform four major functions in the body (Table 15.1). They are an inte- E gral structural component of skeletal muscle, bone, connective tissues (skin, colla- I gen, and cartilage), organs (such as the heart, , and kidneys), red blood cells and V hemoglobin, hair, and fingernails. Proteins are the basic substance that make up E digestive enzymes and the thousands of other enzymes in the human body, and they are a major component of hormones such as insulin. All protein-containing struc- R Other tures and tissues in the body require ongoing maintenance in the form of renewal of R their content of protein. Tissue maintenance and the repair of organs and tissues damaged due to illness or injury are functions of different types of protein. Finally, O protein serves as an energy source.1 F The body of a 154-pound man contains approximately 24 pounds of protein. Nearly half of the protein is found in muscle, while the rest is present in the skin, Brown_U15_1-12.qxd 5/21/04 11:23 AM Page 3

E S U Tony Freeman/PhotoEdit Tony Tony Freeman/PhotoEdit Tony Freeman/PhotoEdit Tony Felicia Martinez/PhotoEdit M O (a) Hamburger (90% lean): 45% (b) Tenderloin: 43% (c) Top loin: 41% (d) RoundO tip: 34% G R N S I S N A Felicia Martinez/PhotoEdit Felicia Martinez/PhotoEdit Felicia Martinez/PhotoEdit R L Felicia Martinez/PhotoEdit A C (e) Sirloin: 33% (f) Eye of round: 26% (g) Top round: 25% (h) chop, lean: 48% E R L O E

Richard Anderson E Richard Anderson G L Felicia Martinez/PhotoEdit Felicia Martinez/PhotoEdit A A G S (i) Pork loin roast: 36% (j) Pork tenderloin: 28% (k) Chicken thigh, no skin: 47% (l) Baked chicken breast, no N R skin: 19% Illustration 15.2 E The fat content of 3-ounce portions of “lean” meats.C The percentageO of calories from fat is indicated for each portion. (A 3-ounce portion of is about the size of a deck of cards.) Each porFtion of meat provides approximately 21 grams of protein. F T collagen, blood, enzymes, and antibodies;O organs such as the heart, liver, and antibodies intestines; and other body parts. All proteinO in the body is continually being Blood proteins that help the turned over, or broken down andY rebuilt. NThis process helps maintain protein tis- body fight particular diseases. sues in optimal condition so theyT continue to function normally. The process of They help the body develop an protein turnover utilizes roughly 9 ounces ± of protein each day. Yet, we consume immunity, or resistance, to onlyR 2–3 ounces of protein daily. Most of the protein many diseases. Eused for Ymaintenance is recycled from protein tissues TABLE 15.1 P and substancesL being turned over. Proteins play key roles in the repair of body tissues by serving as sub- FUNCTIONS OF PROTEIN. O stancesN such as fibrin that helps blood clot (Illustration 1. Serves as a structuralR 15.3)O and by replacing tissue proteins damaged by ill- material in muscles, ness or injury.2 connective tissue,P organs, and W Illustration 15.3 hemoglobin E Red blood cells enmeshed in I Index Stock 2. Serves as the basic fibrin in a color-enhanced component ofV microphotograph. enzymes andE Red blood cells and fibrin hormonesR (which helps stop bleeding by 3. Maintains and repairs causing blood to clot) are protein-containingR made primarily from protein. tissues 4.O Serves as an energy Fsource Brown_U15_1-12.qxd 6/7/04 7:50 AM Page 4

E S Protein serves as a source of energy in healthy people,U but not nearly to the extent that and do. Protein is unlike and fat in that it contains nitrogen and doesM not have a storage form in the body. In order to use protein for energy, amino acids that make up proteins must first be stripped ofO their nitrogen. The free nitrogen can be used as a component ofO protein formation within the body; or, if present in excess, it is excreted in urine. Excre- tion of nitrogen requires water, so highG intakeR of protein increases water need. Amino acids missing theirN nitrogenS component are con- verted to or fat that then canI be usedS to form energy. A small amount of protein (1%) can be Nobtained Afrom the liver and blood and used to cover occasional deficitsR in proteinL intake.3 A C Amino Acids E R L The “building blocks” of protein O are amino acids (Illustration 15.4). Illustration 15.4 Protein consumed in is brokenE down by digestive enzymes and absorbed into Source: © 2001 by Sidney Harris. E the bloodstream as amino acids.G There are 20 common amino acids (Table 15.2) that form proteins when linked together.L Every protein in the body is composed of a DNA (deoxyribonucleic unique combination of aminoA acidsA linked together in chains (Illustration 15.5). The ) organization of amino acidsG into the chains is orchestrated by DNA, the genetic mate- Genetic material contained in S rial within each cell Nthat directs protein synthesis. Once formed, the chains of amino cells that initiates and directs acids may fold up into a complexR shape. Some proteins are made of only a few amino the production of proteins in acids, while otherE proteins contain hundreds. Whatever the number of amino acids, the body. O the specific amino C acidsF involved and their arrangement determine whether the pro- essential amino acids tein is an enzyme,F a component of red blood cells, a muscle fiber, or another tissue Amino acids that cannot be made from protein.T Nine of the 20 common amino acids are considered essential, synthesized in adequate and 11 areO nonessential. Despite the labels, all 20 amino acids are required to build amounts by humans and and maintain proteinO tissues. The essential amino acids are called “essential” because therefore must be obtained the bodyY cannot produce them, or produce enough of them, so they must be provided N from the diet. They are some- byT the diet.± Proteins in foods contain both essential and nonessential amino acids. times referred to as “indispens- R able amino acids.” ProteinsY Differ in Quality nonessential amino acids E The ability of proteins to support protein tissue construction in the body varies Amino acids that can be read-P L depending on their content of essential amino acids. How well dietary proteins sup- ily produced by humans from N O port protein tissue construction is captured by tests of the protein’s “quality.” components of the diet.R Also O referred to as “dispensableP amino acids.” W E I Glutamic acid Asparagine Glutamine Cysteine Cysteine Cysteine Tyrosine Leucine Serine V Valine E R Illustration R15.5 Phenylalanine Phenylalanine chains in the Glutamic acid Glutamic acid Asparagine Glutamine Histidine Cysteine Cysteine Tyrosine Tyrosine Alanine Alanine Leucine Leucine Leucine Leucine Glycine Glycine Glycine Serine protein insulinO (shown at Valine Valine Valine right)F and the structure of insulin (shown above). Brown_U15_1-12.qxd 6/7/04 7:50 AM Page 5

E TABLE 15.2 S ESSENTIAL AND NONESSENTIAL AMINO ACIDS. U

ESSENTIAL NONESSENTIAL Richard Anderson M

Histidine Alanine Glutamine O Isoleucine Valine Arginine Glycine O Leucine Asparagine Proline Lysine Serine G R Cysteine Tyrosine N S Phenylalanine Glutamic acid I S Threonine N A R L Illustration 15.6 A C sources of protein Proteins of high quality contain all the essential amino acidsE in the amounts supply “complete proteins.” needed to support protein tissue formation by the body. If any of the essentialR amino Each food shown is a source of L acids are missing in the diet, proteins are not formed—even those proteinsO that could . be produced from available amino acids. Shutting off all proteiEn formation for want of an amino acid or two may appear inefficient; but if the body did notE cease all pro- tein formation, cells would end up with an imbalanced assortmenG tL of proteins. This complete proteins would seriously affect cell functions. When the requiredA level of an essential amino Proteins that contain all of acid is lacking, the remaining amino acids are primarily used forA energy. the essential amino acids in Amino acids cannot be stored very long in the body,G so weS need a fresh supply amounts needed to support of essential amino acids daily. This means we needN to consumeR foods that provide a growth and tissue maintenance. sufficient amount of all essential amino acids everyE day. incomplete proteins C O Proteins that are deficient in Complete Proteins] Food sources of high-quality F protein (meaning they contain one or more essential amino all the essential amino acids in the amountF needed to support protein formation) acids. are called complete proteins. Proteins in this categoryT include those found in ani- mal products such as meat, , and O eggs (Illustration 15.6). Incomplete proteins are O deficient in one or more essentialY aminoN Photo Disc Photo Disc acids. Proteins in plants are “incomplete,”T ± although are consideredR a com- plete source of protein forE adults.Y4 (Soy- may not meet the essential aminoL acid requirements of youngP infants.) You can “complement” the Oessential Namino acid composition of plantR sources O of protein by combining themP to form a “complete” source of protein. IllustrationW 15.7 shows a few plant combinationsE that produce com- plete proteins. I Vegetarian Diets]V Diets consisting only of plant foods can provide an adequate amount

E David Young-Wolff/PhotoEdit of completeR proteins. The key to success is eating a variety of complementary sources of protein eachR day. Vegetarian diets have been practiced for centuries by some religious and Illustration 15.7 culturalO groups, bearing testimony to their Each of these combinations of plant foods is also a source of complete generalF adequacy and safety. (Unit 16 on protein. Shown are mixed vegetables, , and brown ; succotash (lima vegetarian diets expands on this topic.) beans and corn), and rice and black beans. Brown_U15_1-12.qxd 5/21/04 11:24 AM Page 6

E S Illustration 15.8 U A wide array of amino acid Amino Acid Supplements supplements are available Because amino acids occur naturally in foods, people often assume they are harmless, over the counter, but the no matter how much is taken (Illustration 15.8). Researchers haveM known for safety of these supplements decades, however, that high intakes of individual amino acids can harmO health. High is unknown. amounts may disrupt normal protein production by overwhelming cells with a surplus of some amino acids and a relative deficit of others. AminoO acid supplements have been known to cause loss of appetite, diarrhea,G and Rother gastrointestinal upsets.5 They increase the workload of the liver Nand kidneysS and the likelihood of 6 Richard Anderson dehydration. The safety of amino acid supplementsI beganS to gain the public’s atten- tion in 1989 when something went wrong. N A The Tryptophan Supplement Scare] RNature’s Loriginal sleeping pill? Safe as a cup of warm milk? Supplements of the aminoA acid Ctryptophan (pronounced “trip-toe- fan”) turned into heartbreaking storiesE of a serious illness that terrified many people. Late in the summer of 1989, people from Rcoast to coast developed a mysterious L illness characterized by painful muscles andO joints, weakness, fever, cough, a rash, and swelling. Some people whoE had the disease described the muscle pain as “like having a charley horse” in every muscle.E Diagnosing the cause of the symptoms turned out to be difficult. WithinG a fewL months, however, the disease was diagnosed as eosinophilia-myalgia syndromeA (EMS). It has no cure. The outbreak was quickly related to tryptophan supplement Ause when researchers confirmed that 98% of the patients with EMS usedG tryptophan. S 7 In March 1990, tryptophan was taken off the market, and people Nwere urgedR to stop taking the supplements. By late 1990, over 1500 cases of EMSE had been reported and at least 37 people died from the disease. Over 15 years later, manyO people who developed EMS from the supplement still have the disease. C ContaminantsF in certain batches of the supplement and tryptophan itself have beenF related to the development of EMS.8 Although history now, the tryptophan scare taughtT us an important lesson about the potential hazards of O amino acid supplements.O Y : TheN Tryptophan Replacement?] A derivative of tryptophan, the hormoneT melatonin± (Illustration 15.9), entered the marketplace shortly after Rtryptophan supplements were banned. In addition to promoting drowsiness and Illustration 15.9 Esleep, melatoninY has been touted as a cure for jet lag and a way to help your body Tryptophan supplements were switchL to a night shift. Studies have produced conflicting results on the ability of banned in the United States P melatonin to facilitate sleep in young adults, but doses of about 1 milligram per on April 23, 1990, a monthO dayN may improve sleep in older adults lacking normal levels of brain melatonin. after their recall. R OIt does not appear to be effective against jet lag or helpful in the switch to night A close chemical relative,P shifts.9 melatonin, is available. Other W Low doses of melatonin (1 milligram per day) do not appear to be harmful, but derivatives of tryptophan are the safety of melatonin supplements is still unclear. As was the case for tryptophan, also available, and safety isE a there is little oversight of the purity or dose levels of melatonin in supplements. concern. I V Can Amino Acid Supplements and Protein Powders Build Muscle?] You E can’t just consume amino acids or protein powders and watch your muscles grow (no matter how convincing the ads that sell such products are).10 If that happened,

Richard Anderson R everyone who wanted a rippled stomach and bulging triceps could have them. No R amino acids or protein powders are delivered directly to our muscles and cause muscles to enlarge. Only exercise and a good diet build muscles (Illustration 15.10). O Most athletes get more than enough protein from their usual diet to support their F need for it—which is not extraordinarily high.11 Brown_U15_1-12.qxd 6/7/04 9:21 AM Page 7

Photo Disc E S Food as a Source of Protein U The average intake of protein in the United States is 75 grams per day, exceeding the RDA for men of 56 grams and that for women of 46 grams.12 Approximately 70% M of the protein consumed by Americans comes from meats, milk, and other animal products.8 Dried beans and are not as well known for their protein, but are O nevertheless good sources (Table 15.3). Plant sources of protein are generally low in O fat, making them a wise choice for consumers who are trying to limit their intake Gof R N S TABLE 15.3 I S FOOD SOURCES OF PROTEIN. N A The adult RDA is 46 grams for women aged 19 to 24 years and 58 grams for men agedR 19 to L 24 years. A C PROTEIN CONTENT FOOD AMOUNT E GRAMS PERCENTAGE OF TOTAL CALORIESR L Animal products O (water packed) 3 oz 24E 89% Shrimp 3 oz 11 84 E 1 G (low-fat) ⁄2 cup 14 69 L Illustration 15.10 steak (lean) 3 oz 26 60 A No amount of protein Chicken (no skin) 3 oz 24 60A powders or amino acid Pork chop (lean) 3 oz 20G S 59 Beef roast (lean) 3 oz 23N 45 supplements will build Skim milk 1 cup 9E R 40 muscles like these. Exercise (haddock) 3 oz 19O 38 and a good diet are needed to Leg of lamb 3 oz C 22 37 build muscles. (low-fat) 1 cup 13 F 34 Hamburger (lean) 3 ozF 24 34 T Egg 1 mediumO 6 32 Swiss cheese 1 oz O 8 30 Sausage (pork links) 3 ozY 17 28 2% milk 1 cup N 8 26 Cheddar cheese 1 ozT ± 7 25 Whole milk 1R cup 8 23 Y Dried beans and nuts E 1 L Tofu P ⁄2 cup 14 38 1 Soybeans (cooked) ⁄2 cupN 10 33 O 1 Split (cooked) ⁄2 cup 5 31 O1 Lima beans (cooked)R ⁄2 cup 6 27 1 Dried beans (cooked)P ⁄2 cup 8 26 1 W ⁄4 cup 9 17 butterE 1 tbs 4 17 Grains I 1 Corn V ⁄2 cup 3 29 1 Egg noodlesE (cooked) ⁄2 cup 4 25 1 (cooked) ⁄2 cup 3 15 Whole- R bread 1 slice 2 15 1 Macaroni (cooked) ⁄2 cup 3 13 WhiteR bread 1 slice 2 13 1 White rice (cooked) ⁄2 cup 2 11 O 1 FBrown rice (cooked) ⁄2 cup 2 10 Brown_U15_1-12.qxd 5/21/04 11:24 AM Page 8

E TABLE 15.4 S fat. Nearly all food sources of protein provide an assortment of Uand min- IRON CONTENT IN A erals as well. Beef and pork are particularly good sources of iron, a often 3-OUNCE SERVING OF lacking in the diets of women (Table 15.4). VARIOUS MEATS. M The RDA for women aged What Happens When a Diet Contains Too LittleO Protein? 19 to 24 years is 15 mil- ligrams. The RDA for men Protein deficiency can occur by itself or in combination with a deficiencyO of calories aged 19 to 24 years is 10 and nutrients. Because food sources of protein generallyG contaiRn essential nutrients milligrams. such as iron, zinc, B12, and , diets thatN produceS protein deficiency usu- ally cause a variety of other deficiencies, too. ProteinI does not generally serve as an IRON S CONTENT important source of energy, but body proteinN will be usedA as a major energy source MEAT (MG) during starvation. To meet the need for energy, the body will extract protein from the liver, intestines, heart, muscles, and otherR organsL and tissues. Loss of more than Pork chop about 30% of body protein results in reducedA bodyC strength for breathing, suscep- (lean) 3.4 tibility to infection, abnormal organ functions,E and death.13 Round steak R is a severe form ofL protein deficiency in children. It usually develops (lean) 3.1 after a child has been weaned from breastO milk and given high-carbohydrate, low- Hamburger protein foods such as orE a watery gruel made from , rice, or corn. A (lean) 3.0 protein-deficient body cannot grow, maintainE a normal level of blood volume, pro- G Shrimp 2.6 duce digestive enzymes, fight infectionsL adequately, or maintain existing tissues in proper working order. As seen in Illustration 15.11, children with kwashiorkor may Tuna 1.6 A look fat due to (swelling), butA they are actually very skinny. Children with pro- Baked chicken tein deficiency are apathetic,G irritable,S small, and highly vulnerable to infection. (no skin) 1.4 Protein deficiencyN may beR accompanied by a lack of calories. In this case, a con- Lamb (lean) 1.3 E dition called , or protein-energy C O , exists. Unfortunately, this F condition is all too frequent in areas of the kwashiorkor (kwa-she-or- F kor) T A deficiency disease primarily O

Dr. Robert S. Goodhard, M.D. Dr. O caused by a lack of complete Y protein in the diet. It usually N occurs after children are taken T ± off breast milk and given solid

R Robert S. Goodhard, M.D. Dr. foods containing low-quality E Y protein. P L edema Swelling due to an accumula-O N tion of fluid in body tissues.R O marasmus P A condition of severe body W wasting due to deficiencies of E Illustration 15.11 both protein and calories.I Also Children suffering from a severe form of called protein-energy malnutri- V protein deficiency called kwashiorkor tion and protein-calorie experience swelling in the arms, legs, and malnutrition. E R stomach area. The swelling hides the dev- Illustration 15.12 astating wasting that is taking place within Individuals with marasmus look as starved as R their bodies. The child at left has the charac- they are. People with this condition lack both teristic “moon face” (edema), swollen belly, protein and calories. The child at left is suffer- O and patchy dermatitis (from zinc deficiency) ing from the extreme emaciation of marasmus. F often seen with kwashiorkor. At right, the At right is the same child after nutritional same child after nutritional therapy. therapy. Brown_U15_1-12.qxd 5/21/04 11:24 AM Page 9

E S REALITY CHECK U

Pure protein M Photo Disc You’ve got a nutrition exam coming up, O so you and your classmate Scenario have gotten together to study. You get into a O discussion about food sources of protein G R that goes like this: N S I S Scenario: Who gets the “thumbs up”N A Pickles: Lean meats are the best R L Pure protein? Even the source. They’re pure driest, toughest meats protein! A C contain more than ? E R protein. L O Answers on nextE page E G L A A world where hunger and famine are common. It is alsoG the type of malnutrition that occurs among people with severe anorexia nervosa and in certain S diseases such as cancer and AIDS. Individuals with marasmus lookN starvedR and wasted (see Illustra- tion 15.12). They have precious little body fat andE must utilize protein from muscles, the liver, and other tissues as an energy source.C O In addition to having a skin-and-bones appearance, F children with marasmus are apathetic, highly susceptible to infection,F and have dry skin and brittle hair. Use of T the fat pads in the cheeks for energy (whichO are among the last fat deposits to be used for energy during starvation) gives children withO advanced cases of marasmus the look of a very old person. Both kwashiorkorY and marasmus are generally accompa- nied by multiple vitamin and mineral deficiencies N due to limited food intake. The conditions are frequently complicatedT by± infection, diarrhea, and dehydration. R How Much ProteinE Is TooY Much? L Adults can consume a substantialP amount of protein—approximately 35% of total calories—for months a time withoutN ill effects. This observation is based on stud- ies of the diets of REskimos, Oexplorers, trappers, and hunters in northern America. The very high-proteinP diets would generally contain a good deal of fat in the form of whale blubber, , Wor fat added to dried meat. Consumption of 45% of total calories from protein Eis considered too high. Consumption of this level of protein is related to nausea, weakness,I and diarrhea. Diets very high in protein result in death after several weeks. The disease resulting from excess protein intake was termed “rabbit fever” afterV it occurred in trappers attempting to exist on wild rabbit only.14 High-proteinE diets have been implicated in the development of weak bones, kid- ney stones, cancer,R heart disease, and obesity. The National Academy of Sciences has concluded that the risk of such disorders does not appear to be increased among individualsR consuming 10 to 35% of total calories from protein, and on average adults consume 15%.15 AO Tolerable Upper Intake Level (UL) for protein has not been established. BecauseF information on the effects of high-protein intakes is limited, people are cau- tioned not to consume high levels of protein from foods or supplements. Brown_U15_1-12.qxd 5/21/04 11:24 AM Page 10

E S ANSWERS TO REALITY CHECK U

Photo Disc Pure protein M Some people think muscle and lean meat con- O sist only of protein. They don’t. By weight, O lean cooked sirloin steak is 29% protein, 8% fat, and 62% water. Lean pork is 29% protein, G R 9% fat, and 61% water, for example. N S I S Scenario N A Pickles R L A C E R L Trends O In the early 1900s about half Eof the protein consumed in the United States came E from plant sources and halfG from animal sources. Now, approximately two-thirds of the protein intake comes from animalL products.16 As countries develop econom- ically, the proportion of dietaryA proteinA obtained from meats tends to increase. The increased intake of proteinG fromS meats is accompanied by an increased consumption of fat and by elevated rates of some of the “diseases of Western civilization” such as heart disease and certainN cancers.R Adequate intakes of protein without excess levels of fat can easily beE obtained from diets that include dried beans, , and other grains as sources of proteinO as well as lean meats and low-fat dairy products. C F F T O Key Terms O antibodies, page 15-3 YessentialN amino acids, page 15-4 nonessential amino acids, page 15-4 T complete proteins, page 15-5 incomplete ± proteins, page 15-5 protein, page 15-2 DNA (deoxyribonucleic acid), R kwashiorkor (kwa-she-or-kor), E Y page 15-4 L page 15-8 edema, page 15-8 P marasmus, page 15-8 O N R O P W www links E www.healthfinder.gov I www.iom.edu www.nal.usda.gov/fnic/etext/macronut.html Search topics related toV protein. Select “Food & Nutrition” to gain access to You will find the topic “protein” listed and www.nemsn.org report on linked to a wealth of information on func- The National EMS NetworkE provides infor- macronutrients and the chapter on Protein. tions, structures, food sources, and more. mation on symptoms,R current issues, and answers to questions about EMS, trypto- phan, and melatonin.R O F Brown_U15_1-12.qxd 5/21/04 11:24 AM Page 11

E S U Nutrition UP CLOSE My Protein Intake M O FOCAL POINT: Determine the amount of protein in your diet yesterday. O G R N S For each serving of a food item If you had one 3-ounce pork Ion the listS closest to it. Then, you ate yesterday, write the chop yesterday, write 20 grams N total theA grams of protein you grams of protein the food con- in the corresponding blank. If R ateL yesterday from both plant tains in the corresponding you had two 3-ounce pork and animal sources. Finally, blank. For example, a standard chops, write 40 grams. If a pro-A compareC your protein intake serving of meat is 3 ounces tein food you ate yesterdayE is R with the RDA of 46 grams for (about the size of the palm of not included, choose theL item women or 56 grams for men. your hand or a deck of cards). O E E G Protein in LOne Serving Protein You Ate Food One ServingA A (grams) (grams) Animal products G Milk (whole) 1 c (8 oz) S 8 Yogurt 1 c (8 oz)N 13 1 R Cottage cheese ⁄2 c (4 Eoz) 14 Hard cheese 1 ozO 7 Hamburger (lean) 3 oz C F 24 Beef steak (lean )F 3 oz 26 Chicken (no skin) 3 ozT 24 Pork chop (lean)O 3 oz 20 Fish 3 ozO 19 Hot dogY 1N 6 Sausage 3 oz 17 T ± Subtotal from animal foods: R Plant products E Y BreadL 1 slice 2 1 Rice P ⁄2 c (4 oz) 2 1 O N ⁄2 c (4 oz) 3 1 Cereals ⁄2 c (4 oz) 3 O 1 Vegetables R ⁄2 c (4 oz) 2 Peanut butterP 1 tbs 4 1 Nuts W ⁄4 c (2 oz) 7 1 Cooked beans ()E ⁄2 c (4 oz) 8 I Subtotal from plant foods: Total grams of protein from V plant and animal foods: E Amount above/below RDA: R Special note: You can also calculate your protein intake using Wadsworth Diet Analysis Plus software. Input your food intakeR for one day. Then go to the Analyses/Reports section to view the total number of grams of protein in your diet. OFEEDBACK can be found at the end of Unit 15. F Brown_U15_1-12.qxd 5/21/04 11:24 AM Page 12

E S Notes U 1. Dietary Reference Intakes. Energy, car- 7. Centers for Disease Control. Update: aids: reported facts and claims, SCAN’s bohydrate, fiber, fat, fatty acids, choles- eosinophilia-myalgia syndrome associ- Pulse 1999;winter:12–21.M terol, protein, and amino acids. Institute ated with ingestion of L-tryptophan— 11. Dietary Reference Intakes, Energy, . . . of Medicine, National Academy of Sci- United States, as of January 9, 1990. amino acids. O ences, Washington, DC: National Acad- JAMA 1990;263–633. emies Press; 2002. 12. Dietary ReferenceO Intakes, Energy, . . . 8. Information paper on 5-hydroxytrypto- amino acids. 2. Dietary Reference Intakes, Energy, . . . phan and 5-hydroxy-L-tryptophan, G R amino acids. www.nal.usda.gov/fnic/etext/macronut 13.N Matthews,S Proteins and amino acids. 3. Matthews DE. Proteins and amino .html, accessed 7/03. 14.I Dietary SReference Intakes, Energy, . . . acids. In: Modern nutrition in health 9. Brzezinski A, Melatonin in humans, N aminoA acids. and disease, 9th edition, Shils ME et al., New Engl J Med 1997;336:186–95; and 15. Dietary Reference Intakes, Energy, . . . eds. Philadelphia: Lippincott, Williams Arendt J, Jet-lag and shift work, Thera-R aminoL acids. & Wilkins, 1998, pp. 11–48. peutic uses of melatonin. J Royal Soc Med 1999;92:402–5. A 16.C McDowell MA et al. Energy and 4. Dietary Reference Intakes, Energy, . . . macronutrient consumption of persons 2 amino acids. 10. Lund BC, Perry PJ, Nonsteroid E R months and over in the United States: 5. Dietary Reference Intakes, Energy, . . . performance-enhancing agentsL in third national Health and Nutrition amino acids. athletic competition: an overview for cli-O Examination Survey, 1988–91. nicians, Medscape Pharmacotherapy:E Hyattsville, MD: National Center for 6. High protein intake harms the kidneys. www.medscape.com/Medscape/ E Health Statistics, 1994. www.healthfinder.gov/high protein diet, pharmacology/journal/2000/v02,n05;G accessed 9/03. accessed Sept. 25, 2000; and ErgogenicL A A G S N E R O C F F T Nutrition O UP CLOSEO My Protein IntakeY N T ± Feedback forR Unit 15 Compare yourE subtotalsY to find out which protein source you prefer, plant or animal. Protein from animalP productsL is often accompanied by fat. If you are concerned about calories and fat in your diet, chooseN plant protein sources more often. And, if you are similar to many Americans, yourO intake of protein will exceed the RDA by quite a bit. R O P W E I V E R R O F