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US E TRUE Nutrition Scoreboard FALSE RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O OM Proteins and Amino Acids 1 The primary function of protein is to provide energy. FO R 3 High-protein diets enhance muscle development in individuals who work out a lot. Answers on next page 2 “Nonessential amino acids” are not required for normal body processes. Only “essential amino acids” are. • Proteins are made of amino acids. Some amino acids are “essential” (required in the diet), and some are “nonessential” (not a required part of diets). • Although protein can be used for energy, its major functions in the body involve the construction, maintenance, and repair of protein tissues. • Protein tissue construc- tion in the body proceeds only when all nine essential amino acids are available. TRUE Answers to Nutrition Scoreboard ] FALSE US E OM KEY CONCEPTS AND FACTS 1 Energy is a function of protein, but it’s not the primary one. ✔ 2 “Nonessential amino acids” are required by the body, but they are not required components of our diet. (Yes, it is confusing.) ✔ 3 Muscles contain protein, but you can’t increase muscle mass by consuming a high-protein diet— whether you’re a couch potato or a nationally ranked athlete. ✔ RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O [ • Appropriate combinations of plant foods can supply sufficient quantities of all the essential amino acids. Protein’s Image versus Reality protein Chemical substance in foods made up of chains of amino acids. Illustration 15.1 The protein perception. FO R Protein The term protein is derived from the Greek word protos, meaning “first.” The derivation indicates the importance ascribed to this substance when it was first recognized. An essential structural component of all living matter, protein is involved in almost every biological process in the human body. Protein has a very positive image (Illustration 15.1). It’s so positive that you don’t have to talk about the importance of protein—people are already convinced of it. Rich or poor, nearly all people in the United States get enough protein in their diets. Actually, most people consume more protein than they need. Average intakes of protein exceed the Recommended Dietary Allowance (RDA) level for all age and sex groups. Approximately 15% of total calories in the average U.S. adult diet are supplied by protein. High-protein intakes are generally accompanied by high-fat and low-fiber intakes. That’s because foods high in protein such as hamburger, cheese, nuts, and eggs are high in fat and contain little or no fiber. Even lean meats provide a considerable proportion of their total calories as fat (Illustration 15.2). Functions of Protein Other nutrients Proteins perform four major functions in the body (Table 15.1). They are an integral structural component of skeletal muscle, bone, connective tissues (skin, collagen, and cartilage), organs (such as the heart, liver, and kidneys), red blood cells and hemoglobin, hair, and fingernails. Proteins are the basic substance that make up 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 structures and tissues in the body require ongoing maintenance in the form of renewal of 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, protein serves as an energy source.1 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, US E OM Felicia Martinez/PhotoEdit Tony Freeman/PhotoEdit Tony Freeman/PhotoEdit RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O Tony Freeman/PhotoEdit (i) Pork loin roast: 36% Felicia Martinez/PhotoEdit (g) Top round: 25% Richard Anderson (j) Pork tenderloin: 28% (d) Round tip: 34% (h) Pork chop, lean: 48% Richard Anderson (f) Eye of round: 26% Felicia Martinez/PhotoEdit Felicia Martinez/PhotoEdit (e) Sirloin: 33% (c) Top loin: 41% Felicia Martinez/PhotoEdit (b) Tenderloin: 43% Felicia Martinez/PhotoEdit Felicia Martinez/PhotoEdit (a) Hamburger (90% lean): 45% (k) Chicken thigh, no skin: 47% (l) Baked chicken breast, no skin: 19% Illustration 15.2 The fat content of 3-ounce portions of “lean” meats. The percentage of calories from fat is indicated for each portion. (A 3-ounce portion of meat is about the size of a deck of cards.) Each portion of meat provides approximately 21 grams of protein. connective tissue, organs, and hemoglobin 2. Serves as the basic component of enzymes and hormones FO R 3. Maintains and repairs protein-containing tissues 4. Serves as an energy source Index Stock collagen, blood, enzymes, and antibodies; organs such as the heart, liver, and intestines; and other body parts. All protein in the body is continually being turned over, or broken down and rebuilt. This process helps maintain protein tissues in optimal condition so they continue to function normally. The process of protein turnover utilizes roughly 9 ounces of protein each day. Yet, we consume only 2–3 ounces of protein daily. Most of the protein used for maintenance is recycled from protein tissues TABLE 15.1 and substances being turned over. Proteins play key roles in the repair of body tissues by serving as subFUNCTIONS OF PROTEIN. stances such as fibrin that helps blood clot (Illustration 1. Serves as a structural 15.3) and by replacing tissue proteins damaged by illmaterial in muscles, ness or injury.2 antibodies Blood proteins that help the body fight particular diseases. They help the body develop an immunity, or resistance, to many diseases. Illustration 15.3 Red blood cells enmeshed in fibrin in a color-enhanced microphotograph. Red blood cells and fibrin (which helps stop bleeding by causing blood to clot) are made primarily from protein. US E RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O OM Protein serves as a source of energy in healthy people, but not nearly to the extent that carbohydrates and fats do. Protein is unlike carbohydrate and fat in that it contains nitrogen and does 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 of their nitrogen. The free nitrogen can be used as a component of protein formation within the body; or, if present in excess, it is excreted in urine. Excretion of nitrogen requires water, so high intake of protein increases water need. Amino acids missing their nitrogen component are converted to glucose or fat that then can be used to form energy. A small amount of protein (1%) can be obtained from the liver and blood and used to cover occasional deficits in protein intake.3 Amino Acids The “building blocks” of protein are amino acids (Illustration 15.4). Protein consumed in food is broken down by digestive enzymes and absorbed into the bloodstream as amino acids. There are 20 common amino acids (Table 15.2) that form proteins when linked together. Every protein in the body is composed of a unique combination of amino acids linked together in chains (Illustration 15.5). The organization of amino acids into the chains is orchestrated by DNA, the genetic material within each cell that directs protein synthesis. Once formed, the chains of amino acids may fold up into a complex shape. Some proteins are made of only a few amino acids, while other proteins contain hundreds. Whatever the number of amino acids, the specific amino acids involved and their arrangement determine whether the protein is an enzyme, a component of red blood cells, a muscle fiber, or another tissue made from protein. Nine of the 20 common amino acids are considered essential, and 11 are nonessential. Despite the labels, all 20 amino acids are required to build and maintain protein tissues. The essential amino acids are called “essential” because the body cannot produce them, or produce enough of them, so they must be provided by the diet. Proteins in foods contain both essential and nonessential amino acids. Illustration 15.4 Source: © 2001 by Sidney Harris. DNA (deoxyribonucleic acid) Genetic material contained in cells that initiates and directs the production of proteins in the body. essential amino acids Amino acids that cannot be synthesized in adequate amounts by humans and therefore must be obtained from the diet. They are sometimes referred to as “indispensable amino acids.” Proteins Differ in Quality nonessential amino acids Amino acids that can be readily produced by humans from components of the diet. Also referred to as “dispensable amino acids.” The ability of proteins to support protein tissue construction in the body varies depending on their content of essential amino acids. How well dietary proteins support protein tissue construction is captured by tests of the protein’s “quality.” Glycine Valine Phenylalanine R Isoleucine Glutamine Histidine Asparagine Cysteine Valine Glutamine Cysteine Glutamic acid Alanine Cysteine Serine Histidine Glycine Valine Serine Valine Glutamic acid Leucine Leucine Leucine Alanine Serine Tyrosine Cysteine Glutamine Leucine Valine Tyrosine Asparagine Glycine Cysteine Leucine Tyrosine Glutamic acid Cysteine Asparagine FO Leucine Arginine Glutamic acid Glycine Phenylalanine Tyrosine Phenylalanine Threonine Lysine Proline Alanine Illustration 15.5 Amino acid chains in the protein insulin (shown at right) and the structure of insulin (shown above). Tryptophan Valine Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine Proline Serine Tyrosine US E RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine NONESSENTIAL Proteins of high quality contain all the essential amino acids in the amounts needed to support protein tissue formation by the body. If any of the essential amino acids are missing in the diet, proteins are not formed—even those proteins that could be produced from available amino acids. Shutting off all protein formation for want of an amino acid or two may appear inefficient; but if the body did not cease all protein formation, cells would end up with an imbalanced assortment of proteins. This would seriously affect cell functions. When the required level of an essential amino acid is lacking, the remaining amino acids are primarily used for energy. Amino acids cannot be stored very long in the body, so we need a fresh supply of essential amino acids daily. This means we need to consume foods that provide a sufficient amount of all essential amino acids every day. Complete Proteins] Food sources of high-quality protein (meaning they contain complete proteins Proteins that contain all of the essential amino acids in amounts needed to support growth and tissue maintenance. incomplete proteins Proteins that are deficient in one or more essential amino acids. FO R Vegetarian Diets] Diets consisting only of plant foods can provide an adequate amount of complete proteins. The key to success is eating a variety of complementary sources of protein each day. Vegetarian diets have been practiced for centuries by some religious and cultural groups, bearing testimony to their general adequacy and safety. (Unit 16 on vegetarian diets expands on this topic.) David Young-Wolff/PhotoEdit Photo Disc all the essential amino acids in the amount needed to support protein formation) are called complete proteins. Proteins in this category include those found in animal products such as meat, milk, and eggs (Illustration 15.6). Incomplete proteins are deficient in one or more essential amino acids. Proteins in plants are “incomplete,” although soybeans are considered a complete source of protein for adults.4 (Soybeans may not meet the essential amino acid requirements of young infants.) You can “complement” the essential amino acid composition of plant sources of protein by combining them to form a “complete” source of protein. Illustration 15.7 shows a few plant combinations that produce complete proteins. Illustration 15.6 Animal sources of protein supply “complete proteins.” Each food shown is a source of complete protein. Illustration 15.7 Each of these combinations of plant foods is also a source of complete protein. Shown are mixed vegetables, tofu, and brown rice; succotash (lima beans and corn), and rice and black beans. Photo Disc ESSENTIAL OM ESSENTIAL AND NONESSENTIAL AMINO ACIDS. Richard Anderson TABLE 15.2 US E Amino Acid Supplements OM Illustration 15.8 A wide array of amino acid supplements are available over the counter, but the safety of these supplements is unknown. Richard Anderson RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O Because amino acids occur naturally in foods, people often assume they are harmless, no matter how much is taken (Illustration 15.8). Researchers have known for decades, however, that high intakes of individual amino acids can harm health. High amounts may disrupt normal protein production by overwhelming cells with a surplus of some amino acids and a relative deficit of others. Amino acid supplements have been known to cause loss of appetite, diarrhea, and other gastrointestinal upsets.5 They increase the workload of the liver and kidneys and the likelihood of dehydration.6 The safety of amino acid supplements began to gain the public’s attention in 1989 when something went wrong. The Tryptophan Supplement Scare] Nature’s original sleeping pill? Safe as a cup of warm milk? Supplements of the amino acid tryptophan (pronounced “trip-toefan”) turned into heartbreaking stories of a serious illness that terrified many people. Late in the summer of 1989, people from coast to coast developed a mysterious illness characterized by painful muscles and joints, weakness, fever, cough, a rash, and swelling. Some people who had the disease described the muscle pain as “like having a charley horse” in every muscle. Diagnosing the cause of the symptoms turned out to be difficult. Within a few months, however, the disease was diagnosed as eosinophilia-myalgia syndrome (EMS). It has no cure. The outbreak was quickly related to tryptophan supplement use when researchers confirmed that 98% of the patients with EMS used tryptophan.7 In March 1990, tryptophan was taken off the market, and people were urged to stop taking the supplements. By late 1990, over 1500 cases of EMS had been reported and at least 37 people died from the disease. Over 15 years later, many people who developed EMS from the supplement still have the disease. Contaminants in certain batches of the supplement and tryptophan itself have been related to the development of EMS.8 Although history now, the tryptophan scare taught us an important lesson about the potential hazards of amino acid supplements. Melatonin: The Tryptophan Replacement?] A derivative of tryptophan, the Richard Anderson Illustration 15.9 Tryptophan supplements were banned in the United States on April 23, 1990, a month after their recall. A close chemical relative, melatonin, is available. Other derivatives of tryptophan are also available, and safety is a concern. hormone melatonin (Illustration 15.9), entered the marketplace shortly after tryptophan supplements were banned. In addition to promoting drowsiness and sleep, melatonin has been touted as a cure for jet lag and a way to help your body switch to a night shift. Studies have produced conflicting results on the ability of melatonin to facilitate sleep in young adults, but doses of about 1 milligram per day may improve sleep in older adults lacking normal levels of brain melatonin. It does not appear to be effective against jet lag or helpful in the switch to night shifts.9 Low doses of melatonin (1 milligram per day) do not appear to be harmful, but the safety of melatonin supplements is still unclear. As was the case for tryptophan, there is little oversight of the purity or dose levels of melatonin in supplements. FO R Can Amino Acid Supplements and Protein Powders Build Muscle?] You 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, everyone who wanted a rippled stomach and bulging triceps could have them. No 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). Most athletes get more than enough protein from their usual diet to support their need for it—which is not extraordinarily high.11 US E Photo Disc RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O 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% of the protein consumed by Americans comes from meats, milk, and other animal products.8 Dried beans and grains are not as well known for their protein, but are nevertheless good sources (Table 15.3). Plant sources of protein are generally low in fat, making them a wise choice for consumers who are trying to limit their intake of OM Food as a Source of Protein TABLE 15.3 FOOD SOURCES OF PROTEIN. The adult RDA is 46 grams for women aged 19 to 24 years and 58 grams for men aged 19 to 24 years. FOOD Animal products Tuna (water packed) Shrimp Cottage cheese (low-fat) Beef steak (lean) Chicken (no skin) Pork chop (lean) Beef roast (lean) Skim milk Fish (haddock) Leg of lamb Yogurt (low-fat) Hamburger (lean) Egg Swiss cheese Sausage (pork links) 2% milk Cheddar cheese Whole milk Dried beans and nuts Tofu Soybeans (cooked) Split peas (cooked) Lima beans (cooked) Dried beans (cooked) Peanuts Peanut butter FO R Grains Corn Egg noodles (cooked) Oatmeal (cooked) Whole-wheat bread Macaroni (cooked) White bread White rice (cooked) Brown rice (cooked) AMOUNT GRAMS PROTEIN CONTENT PERCENTAGE OF TOTAL CALORIES 3 oz 3 oz 1 ⁄2 cup 3 oz 3 oz 3 oz 3 oz 1 cup 3 oz 3 oz 1 cup 3 oz 1 medium 1 oz 3 oz 1 cup 1 oz 1 cup 24 11 14 26 24 20 23 9 19 22 13 24 6 8 17 8 7 8 89% 84 69 60 60 59 45 40 38 37 34 34 32 30 28 26 25 23 1 14 10 5 6 8 9 4 38 33 31 27 26 17 17 3 4 3 2 3 2 2 2 29 25 15 15 13 13 11 10 ⁄2 cup ⁄2 cup 1 ⁄2 cup 1 ⁄2 cup 1 ⁄2 cup 1 ⁄4 cup 1 tbs 1 1 ⁄2 cup ⁄2 cup 1 ⁄2 cup 1 slice 1 ⁄2 cup 1 slice 1 ⁄2 cup 1 ⁄2 cup 1 Illustration 15.10 No amount of protein powders or amino acid supplements will build muscles like these. Exercise and a good diet are needed to build muscles. US E What Happens When a Diet Contains Too Little Protein? 3.4 Round steak (lean) 3.1 Hamburger (lean) 3.0 Shrimp 2.6 1.6 Baked chicken (no skin) 1.4 Lamb (lean) 1.3 kwashiorkor (kwa-she-orkor) A deficiency disease primarily caused by a lack of complete protein in the diet. It usually occurs after children are taken off breast milk and given solid foods containing low-quality protein. Dr. Robert S. Goodhard, M.D. Pork chop (lean) Protein deficiency can occur by itself or in combination with a deficiency of calories and nutrients. Because food sources of protein generally contain essential nutrients such as iron, zinc, vitamin B12, and niacin, diets that produce protein deficiency usually cause a variety of other deficiencies, too. Protein does not generally serve as an important source of energy, but body protein will be used as a major energy source during starvation. To meet the need for energy, the body will extract protein from the liver, intestines, heart, muscles, and other organs and tissues. Loss of more than about 30% of body protein results in reduced body strength for breathing, susceptibility to infection, abnormal organ functions, and death.13 Kwashiorkor is a severe form of protein deficiency in children. It usually develops after a child has been weaned from breast milk and given high-carbohydrate, lowprotein foods such as cassava or a watery gruel made from oats, rice, or corn. A protein-deficient body cannot grow, maintain a normal level of blood volume, produce digestive enzymes, fight infections adequately, or maintain existing tissues in proper working order. As seen in Illustration 15.11, children with kwashiorkor may look fat due to edema (swelling), but they are actually very skinny. Children with protein deficiency are apathetic, irritable, small, and highly vulnerable to infection. Protein deficiency may be accompanied by a lack of calories. In this case, a condition called marasmus, or protein-energy malnutrition, exists. Unfortunately, this condition is all too frequent in areas of the Dr. Robert S. Goodhard, M.D. MEAT IRON CONTENT (MG) Tuna fat. Nearly all food sources of protein provide an assortment of vitamins and minerals as well. Beef and pork are particularly good sources of iron, a mineral often lacking in the diets of women (Table 15.4). RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O IRON CONTENT IN A 3-OUNCE SERVING OF VARIOUS MEATS. The RDA for women aged 19 to 24 years is 15 milligrams. The RDA for men aged 19 to 24 years is 10 milligrams. OM TABLE 15.4 edema Swelling due to an accumulation of fluid in body tissues. FO R marasmus A condition of severe body wasting due to deficiencies of both protein and calories. Also called protein-energy malnutrition and protein-calorie malnutrition. Illustration 15.11 Children suffering from a severe form of protein deficiency called kwashiorkor experience swelling in the arms, legs, and stomach area. The swelling hides the devastating wasting that is taking place within their bodies. The child at left has the characteristic “moon face” (edema), swollen belly, and patchy dermatitis (from zinc deficiency) often seen with kwashiorkor. At right, the same child after nutritional therapy. Illustration 15.12 Individuals with marasmus look as starved as they are. People with this condition lack both protein and calories. The child at left is suffering from the extreme emaciation of marasmus. At right is the same child after nutritional therapy. US E RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O You’ve got a nutrition exam coming up, so you and your classmate Scenario have gotten together to study. You get into a discussion about food sources of protein that goes like this: Scenario: Lean meats are the best source. They’re pure protein! Who gets the “thumbs up” ? Answers on next page world where hunger and famine are common. It is also the type of malnutrition that occurs among people with severe anorexia nervosa and in certain diseases such as cancer and AIDS. Individuals with marasmus look starved and wasted (see Illustration 15.12). They have precious little body fat and must utilize protein from muscles, the liver, and other tissues as an energy source. In addition to having a skin-and-bones appearance, children with marasmus are apathetic, highly susceptible to infection, and have dry skin and brittle hair. Use of the fat pads in the cheeks for energy (which are among the last fat deposits to be used for energy during starvation) gives children with advanced cases of marasmus the look of a very old person. Both kwashiorkor and marasmus are generally accompanied by multiple vitamin and mineral deficiencies due to limited food intake. The conditions are frequently complicated by infection, diarrhea, and dehydration. How Much Protein Is Too Much? FO R Adults can consume a substantial amount of protein—approximately 35% of total calories—for months at a time without ill effects. This observation is based on studies of the diets of Eskimos, explorers, trappers, and hunters in northern America. The very high-protein diets would generally contain a good deal of fat in the form of whale blubber, lard, or fat added to dried meat. Consumption of 45% of total calories from protein is considered too high. Consumption of this level of protein is related to nausea, weakness, and diarrhea. Diets very high in protein result in death after several weeks. The disease resulting from excess protein intake was termed “rabbit fever” after it occurred in trappers attempting to exist on wild rabbit only.14 High-protein diets have been implicated in the development of weak bones, kidney stones, cancer, heart disease, and obesity. The National Academy of Sciences has concluded that the risk of such disorders does not appear to be increased among individuals consuming 10 to 35% of total calories from protein, and on average adults consume 15%.15 A Tolerable Upper Intake Level (UL) for protein has not been established. Because information on the effects of high-protein intakes is limited, people are cautioned not to consume high levels of protein from foods or supplements. Pickles: Pure protein? Even the driest, toughest meats contain more than protein. Photo Disc Pure protein OM REALITY CHECK US E REALITY CHECK Pure protein RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O Some people think muscle and lean meat consist only of protein. They don’t. By weight, lean cooked sirloin steak is 29% protein, 8% fat, and 62% water. Lean pork is 29% protein, 9% fat, and 61% water, for example. OM Photo Disc ANSWERS TO Scenario Pickles Trends In the early 1900s about half of the protein consumed in the United States came from plant sources and half from animal sources. Now, approximately two-thirds of the protein intake comes from animal products.16 As countries develop economically, the proportion of dietary protein obtained from meats tends to increase. The increased intake of protein from 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 certain cancers. Adequate intakes of protein without excess levels of fat can easily be obtained from diets that include dried beans, cereals, and other grains as sources of protein as well as lean meats and low-fat dairy products. Key Terms antibodies, page 15-3 essential amino acids, page 15-4 nonessential amino acids, page 15-4 complete proteins, page 15-5 incomplete proteins, page 15-5 protein, page 15-2 DNA (deoxyribonucleic acid), kwashiorkor (kwa-she-or-kor), page 15-4 edema, page 15-8 page 15-8 marasmus, page 15-8 www links www.healthfinder.gov Search topics related to protein. FO R www.nemsn.org The National EMS Network provides information on symptoms, current issues, and answers to questions about EMS, tryptophan, and melatonin. www.iom.edu Select “Food & Nutrition” to gain access to Dietary Reference Intake report on macronutrients and the chapter on Protein. www.nal.usda.gov/fnic/etext/macronut.html You will find the topic “protein” listed and linked to a wealth of information on functions, structures, food sources, and more. US E UP CLOSE OM Nutrition RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O My Protein Intake FOCAL POINT: Determine the amount of protein in your diet yesterday. For each serving of a food item you ate yesterday, write the grams of protein the food contains in the corresponding blank. For example, a standard serving of meat is 3 ounces (about the size of the palm of your hand or a deck of cards). Food Animal products Milk (whole) Yogurt Cottage cheese Hard cheese Hamburger (lean) Beef steak (lean ) Chicken (no skin) Pork chop (lean) Fish Hot dog Sausage Plant products Bread Rice Pasta Cereals Vegetables Peanut butter Nuts Cooked beans (legumes) If you had one 3-ounce pork chop yesterday, write 20 grams in the corresponding blank. If you had two 3-ounce pork chops, write 40 grams. If a protein food you ate yesterday is not included, choose the item One Serving 1 c (8 oz) 1 c (8 oz) 1 ⁄2 c (4 oz) 1 oz 3 oz 3 oz 3 oz 3 oz 3 oz 1 3 oz 1 slice ⁄2 c (4 oz) 1 ⁄2 c (4 oz) 1 ⁄2 c (4 oz) 1 ⁄2 c (4 oz) 1 tbs 1 ⁄4 c (2 oz) 1 ⁄2 c (4 oz) 1 Protein in One Serving (grams) on the list closest to it. Then, total the grams of protein you ate yesterday from both plant and animal sources. Finally, compare your protein intake with the RDA of 46 grams for women or 56 grams for men. Protein You Ate (grams) 8 13 14 7 24 26 24 20 19 6 17 Subtotal from animal foods: 2 2 3 3 2 4 7 8 Subtotal from plant foods: Total grams of protein from plant and animal foods: Amount above/below RDA: FO R Special note: You can also calculate your protein intake using Wadsworth Diet Analysis Plus software. Input your food intake for one day. Then go to the Analyses/Reports section to view the total number of grams of protein in your diet. FEEDBACK can be found at the end of Unit 15. US E 7. Centers for Disease Control. Update: eosinophilia-myalgia syndrome associated with ingestion of L-tryptophan— United States, as of January 9, 1990. JAMA 1990;263–633. aids: reported facts and claims, SCAN’s Pulse 1999;winter:12–21. 11. Dietary Reference Intakes, Energy, . . . amino acids. RE VI PR EW O P ON E R LY T Y ± N OF OT C E N FO G A R GE SA LE LEA OR R N CL ING AS SR O 1. Dietary Reference Intakes. Energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Institute of Medicine, National Academy of Sciences, Washington, DC: National Academies Press; 2002. OM Notes 8. Information paper on 5-hydroxytryptophan and 5-hydroxy-L-tryptophan, www.nal.usda.gov/fnic/etext/macronut .html, accessed 7/03. 2. Dietary Reference Intakes, Energy, . . . amino acids. 3. Matthews DE. Proteins and amino acids. In: Modern nutrition in health and disease, 9th edition, Shils ME et al., eds. Philadelphia: Lippincott, Williams & Wilkins, 1998, pp. 11–48. 4. Dietary Reference Intakes, Energy, . . . amino acids. 5. Dietary Reference Intakes, Energy, . . . amino acids. 6. High protein intake harms the kidneys. www.healthfinder.gov/high protein diet, accessed 9/03. Nutrition 9. Brzezinski A, Melatonin in humans, New Engl J Med 1997;336:186–95; and Arendt J, Jet-lag and shift work, Therapeutic uses of melatonin. J Royal Soc Med 1999;92:402–5. 10. Lund BC, Perry PJ, Nonsteroid performance-enhancing agents in athletic competition: an overview for clinicians, Medscape Pharmacotherapy: www.medscape.com/Medscape/ pharmacology/journal/2000/v02,n05; accessed Sept. 25, 2000; and Ergogenic 12. Dietary Reference Intakes, Energy, . . . amino acids. 13. Matthews, Proteins and amino acids. 14. Dietary Reference Intakes, Energy, . . . amino acids. 15. Dietary Reference Intakes, Energy, . . . amino acids. 16. McDowell MA et al. Energy and macronutrient consumption of persons 2 months and over in the United States: third national Health and Nutrition Examination Survey, 1988–91. Hyattsville, MD: National Center for Health Statistics, 1994. UP CLOSE My Protein Intake Feedback for Unit 15 FO R Compare your subtotals to find out which protein source you prefer, plant or animal. Protein from animal products is often accompanied by fat. If you are concerned about calories and fat in your diet, choose plant protein sources more often. And, if you are similar to many Americans, your intake of protein will exceed the RDA by quite a bit.