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Nutrition KNR 240 Objectives What are the different kinds of nutrients, and what functions do they perform in the body? How does the body use the foods we consume for fuel? What percentages of calories come from protein, fats, and carbohydrates in the average American diet, and what percentages of these nutrients are recommended? Objectives What guidelines have been developed to help people choose a healthy diet, avoid nutritional deficiencies, and protect themselves from diet-related chronic diseases? How can people adapt nutritional information to their own lives and circumstances? Nutrition is: A vitally important component of wellness. Closely linked with MAJOR CHRONIC DISEASE certain diseases, RISK disabling conditions, and other health HEART DISEASE CANCER STROKE DIABETES problems. THERE IS A LINK BETWEEN LIFETIME NUTRITIONAL HABITS AND THESE DISEASES!! However… A WELL PLANNED DIET IN CONJUNCTION WITH A FITNESS PROGRAM CAN HELP PREVENT SUCH CONDITIONS AND EVEN REVERSE SOME OF THEM!! So, the goals of this section are to: Understand the basic principles of nutrition. Learn the six classes of essential nutrients, Learn the role of these essential nutrients in the body. Understand the guidelines that are available to help YOU design a food plan for health and wellness for yourself….. Understand the guidelines that are available to help YOU design a food plan for health and wellness for your athletes… FOODS ARE COMPOSED OF: Proteins Carbohydrates Fats Vitamins Minerals Water ESSENTIAL NUTRIENTS Are nutrients that we must include in our diet. Our body does not manufacture them. Nutrition Nutrients are released into the body by the process of DIGESTION The Energy in Foods is measured in kilocalories. 1 kcal represents the amount of heat it takes to raise the temp. of 1 kg of water 1 degree C. The Process of Digestion SIX CLASSES OF ESSENTIAL NUTRIENTS 3 PROVIDE 3 DO NOT ENERGY PROVIDE ENERGY fat vitamins protein minerals carbohydrates water Food Energy Fats Provide the most energy. 9 calories per gram. Carbohydrates Provide 4 calories per gram Proteins Provide 4 calories per gram. Alcohol Although alcohol is not an essential nutrient, it does provide energy. Alcohol provides 7 calories per gram Nutrients: •Although vitamins, minerals, and water do not provide energy, they are still VITAL! •The body is approximately 60% water, and can survive only a few days without it. •All foods are combinations of the different kinds of nutrients. Energy and ATP Production Metabolism is---‖The sum of all the chemical processes necessary to maintain the body.‖ Energy is required to fuel vital body functions. The rate at which your body uses energy (its metabolic rate) depends on your level of activity. So, where does the energy come from????? The body converts chemical energy from food into substances that cells can use as fuel. These fuels can be used immediately or stored. Carbohydrates •During digestion, most carbohydrates are broken down into glucose. •Some glucose remains in the blood and some is converted to glycogen and is stored in the liver, muscles, and kidneys. •Remaining glucose is converted to fat and stored in adipose. Protein Used primarily for building of new tissues. Can be broken down for energy when other fuels not available. Excess can be converted and stored as fat. Fat Excess fat is stored as fat. ATP Adenosine triphosphate- Is the basic form of energy used by the cells. ATP is ―The energy currency of cells‖ When a cell needs energy, it breaks down ATP, which is a process that releases energy in the only form the cell can use directly. Cells do store a minute amount of ATP, but when more is needed, it is created through the chemical reactions that break down the body’s stored fuels- glucose, glycogen, and fat. Metabolic pathway map. Exercise and the three energy systems The muscles in your body have three energy systems by which they can create ATP and fuel cellular activity. These systems use different fuels and chemical processes, and they perform different, specific functions during exercise. Immediate energy system ATP-CP stores Very short duration (<10sec.) Very high intensity Rapid ATP production Uses existing ATP, CP Anaerobic. Non-oxidative (Anaeroic) Lactate Path Short duration (10sec to 2 min.) High intensity Rapid rate of production of ATP Glucose and glycogen used in process called glycolysis Anaerobic-no oxygen used. Produces lactic acid Oxidative (Aerobic) Used in activities longer than 2 minutes Low to moderate intensity Slower production of ATP, but is prolonged Fuel used is glycogen, glucose, fat, and protein Oxygen is required (aerobic) ATP production occurs in the mitochondria. The mitochondria can use either glucose or fats to produce ATP. The fuel used depends on the intensity of the exercise. Oxidative-Aerobic continued Maximal Oxygen Consumption (VO2 max). Determined by the ability of the body to uptake, distribute, and utilize oxygen. Determined partly on genetics, and partly on fitness status. Considered the best overall measure of the capacity of the CR system. Energy systems in combination Your body typically uses all three energy systems when you exercise. The intensity and duration of the activity will determine which system predominates. Fitness status Previous diet See Figure 9.8 p. 304 Fat and carbohydrate are the primary fuels for endurance exercise. See Table 9.9, p. 304 for substrate stores. So……. How does one choose foods that will best fuel their body? From an energy perspective From a health/wellness/disease prevention perspective???? Dietary Guidelines for Health and Disease Prevention Dietary Guidelines for Americans Aim for Fitness Build a healthy base Choose sensibly Aim for Fitness 1. Aim for a healthy weight As previously discussed, 55% of adults and 22% of children and adolescents are overweight and obese in the US today. OW and OB are linked with HTN, heart disease, stroke, diabetes, certain cancers, arthritis, and other types of illnesses. Calories in—Calories out Aim for Fitness 2. Be physically active every day. More than 60% of American adults do not engage in recommended amounts of physical activity. 25% of American adults are not active at all. Only about 15% of American adults engage in regular, daily, moderate physical activity for at least 30 minutes per day. Refer to Table 1.1, p. 7 in text. Build a Healthy Base 3. Let the Food Guide Pyramid be your guide Build a Healthy Base The FGP was developed by the USDA to help consumers translate nutrient recommendations into a plan for healthy eating. Range of serving sizes from six food groups. Total number of servings needed depends on caloric needs. 1600-2800 calories/day See Box 9.3, p. 289. Build a Healthy Base Within each food group, foods vary in the amount of nutrients and calories they provide. Not all foods are created equal! All foods can fit! Best choices emphasize nutrient density— those that are high in nutrients relative to the amount of calories they contain. E.g.: A slice of whole grain bread compared to a croissant. Build a Healthy Base Build a Healthy Base Build a Healthy Base Dietary practices of children and adolescents. Proportion of persons aged 2 & older who: Consume: 2010 Current Target Baseline (%) (%) three or more daily servings of vegetables, with 33% from dark green & yellow veggies 3 50 six or more daily servings of grain products, three or more from whole grain 7 50 two or more daily servings of fruit 28 75 less than 30% of calories from fat 33 75 less than 10% of calories from saturated fat 36 75 meet dietary recommendation for calcium 46 75 Build a Healthy Base 4. Choose a variety of Grains daily, especially whole grains. Most foods chosen each day should come from this segment of the pyramid. Choosing more whole-grain products will increase consumption of total % carbohydrates and fiber, and will decrease fat consumption. Choose unrefined, whole grains over refined, processed foods. Recommendation is for AT LEAST 55% of total calories to come from carbohydrates, with no more than 10-15% of these to come from simple carbohydrate sources. Simple Carbohydrates Contain only one or two sugar units in each molecule. One-unit molecule= MONOSACCHARIDE glucose, fructose, and galactose Two unit molecule = DISACCHARIDE. These include: sucrose (table sugar) fructose + glucose maltose (malt sugar) glucose + glucose lactose (milk sugar) glucose + galactose. Simple carbs provide much of the sweetness in foods. Complex Carbohydrates Starches and most types of dietary fiber. SOLUBLE: slows the absorption of glucose, binds cholesterol, which reduces serum cholesterol and CAD risk. INSOLUBLE: binds water, making feces bulkier and softer Both kinds of fiber contribute to disease prevention. A diet high in soluble fiber can help people manage diabetes and high chol. levels. A diet high in insoluble fiber can help prevent constipation, hemorrhoids, diverticulitis and colon and rectal cancers Some research suggests it may also reverse pre-CA changes. Consist of chains of many glucose molecules. Are called POLYSACCHARIDES. All plant foods contain some dietary fiber. Those particularly rich in fiber include fruits, legumes, oats (oat bran), barley, and psyllium. Wheat (bran) cereals, grains, and veggies are good sources of insoluable fiber See Table 9.3, p. 292 Recommendation for daily fiber intake is 20-35 grams. Current intake is about 14 grams. Refined vs. Unrefined The processing of packaged foods can remove fiber. Refined carbohydrates retain all the calories, but are lower in fiber, vitamins, and minerals. Unrefined carbohydrates take longer to chew and digest, and enter the blood more slowly. These have many health benefits. Feel fuller longer, more anti-oxidant vitamins and phytochemicals, and decreased risk of diabetes. Build a Healthy Base 5. Choose a variety of fruits and vegetables daily. Fruits and veges are complex foods containing more than 100 beneficial vitamins, minerals, fiber, and other substances such as phytochemicals. Build a Healthy Base Phytochemicals and Antioxidants Much new research being done on these. Are said to aid in the preservation of the body’s healthy cells. Free-radicals damage cell membranes and cause gene mutations. Build a Healthy Base A Free Radical is a chemically unstable molecule that is missing an electron. It will react with any molecule it encounters from which it can take an electron. (For example fats, proteins and DNA. This damages cell membranes and mutates genes. Therefore, they have been implicated in aging, cancer, cardiovascular disease, and degenerative diseases such as arthritis. Environmental factors such as cigarette smoking, exhaust fumes, radiation, excessive sun exposure, certain drugs, and stress can increase free radical production. Antioxidants react with free radicals and donate lost electrons. They help by blocking the formation and action of free radicals and repair the damage they cause. Vitamin C, Vitamin A (beta-carotene), Vitamin E and selenium are a few examples of antioxidants. Build a Healthy Base Phytochemicals Anti-oxidants are a particular type of phytochemical which is a substance found in plant foods that may help prevent chronic diseases. Examples of phytochemicals include sulforaphane (found in cruciferous veges), allyl sulfides, and isoflavones. See handout Build a Healthy Base 6. Keep food safe to eat. Food-borne illness is caused by eating foods that contain harmful bacteria, toxins, parasites, viruses, or chemical contaminants. S/S of having eaten unsafe food may appear within half an hour, or may not develop for up to 3 weeks. Refer to p. 294 for steps to follow to keep food safe. Choose Sensibly 7. Choose a diet that is low in saturated fat and cholesterol and moderate in total fat. Most fats in food are in the form of triglycerides. Triglycerides are composed of a glycerine molecule (an alcohol) plus three fatty acid chains. Fatty acids are made up of a chain of carbon atoms with oxygen attached at the end and hydrogen atoms attached along the length of the chain. Fatty acids differ in the length of their carbon atom chains. Choose Sensibly Choose Sensibly Cholesterol Is a type of fat (sterol) found in animal products only. It is manufactured by the body in the liver. High levels of cholesterol are linked to coronary artery disease. RDA for cholesterol is less than 300 mg./day Choose Sensibly Fatty acids also differ by their degree of saturation. Fats are classified as saturated or unsaturated depending on the amount of double bonds located between the carbon atoms. If no double bonds exist between carbons, a fat is classified as ―Saturated‖. Fats are unsaturated depending on the amount of double bonds between C atoms. FA’s with one double bond are called MONOUNSATURATED. FA’s with two or more double bonds are called POLYUNSATURATED. Choose Sensibly Main sources of saturated fats in the American diet are: hamburger, steak, roast, poultry skin, ice cream, and many baked products, cheese, coconut and palm oil, Crisco and butter. These are solid at room temperature. Choose Sensibly Foods that are classified as mono or poly unsaturated typically come from plant sources. They are liquid at room temperature. This is because there is not as many hydrogen bonds to the carbons. Main sources include oils, except palm and coconut oil. Mono’s=olive, canola, safflower and peanut Poly’s=corn, soybean and cottonseed Choose Sensibly Choose Sensibly The process of adding hydrogen to an oil to improve the texture of foods and increase shelf life. Also helps the fat be more capable of withstanding high temperatures for frying. Turns a liquid oil into a solid. Turns the double bonds in unsaturated fats to single bonds, thereby increasing the degree of saturation and producing a more solid fat from a liquid oil. Margarine... The process of hydrogenation produces fatty acids that are not quite the same as a saturated fat, and are referred to as trans-fatty acids. Read on nutrition labels as hydrogenated or partially- hydrogenated vegetable oils. Leads to health risk due to increase in cholesterol level. Refer to Figure 9.4, p. 295 for fatty acid structure and food sources. Chemical Structure of Fatty Acids Choose Sensibly Choose Sensibly Omega-3 Fatty Acids Is a form of polyunsaturated fat. Found in many kinds of fish. May play a role in CAD prevention. Has been found to reduce the tendency of the blood to clot, to decrease inflammatory responses, helps heart to beat in a steady rhythm, and to increase HDL levels in women. Recommendations is to have two or more servings fish/week. Examples: salmon, tuna, trout, mackerel, herring, sardines, and anchovies. Plant sources include dark green leafy veges, walnuts, and flax seeds. Choosing Sensibly Calculating Fat %, Reading Food Labels Find the food nutrition label. Look at the total number of calories and fat grams in one serving. Multiply the number of fat grams by 9. Divide that number by the number of total calories. Result is percent of calories that product has that come from a fat. Refer to Figure 9.3, p. 293. Example: Ho-Ho’s Serving size = 2 rolls. Calories per serving = 290. Total Fat per serving = 15 grams Saturated fat = 7 grams. Calculate: 15 X 9 = 135, thus 135 calories are fat calories. 135 / 290 = 0.465 or 47%. SO, 47% of the calories in a HO-HO is from fat, and 22% is from Sat. fat. YUCK!!! Choose Sensibly High saturated and trans-fat in the diet increases level of serum cholesterol and LDL, and lowers HDL. High LDL leads to increased risk of CAD. Consumption of unsaturated fats may lead to a decrease in total serum cholesterol Mono-unsaturated fats may lower total cholesterol and LDL, yet have no effect or may raise HDL Poly-unsaturated fats may also lower total cholesterol and LDL, but tend to also lower HDL Diet high in fat may also lead to cancer and weight management problems. Choose Sensibly To lower trans fats, decrease intake of: Deep-fat fried foods and baked goods made with hydrogenated vegetable oils. Choose: Liquid oils rather than margarine or shortening for cooking, and flavor tub or squeeze margarines or those labeled low-trans or trans- free over standard stick margarines. Remember, the softer or more liquid the fat is, the less saturated and trans fat it is likely to contain. Choose Sensibly: Reducing the fat in your diet See list on p. 296, text. Be moderate in your intake of fast foods, commercially prepared baked goods and desserts, deep-fried foods, meat, poultry, nuts and seeds, and regular dairy products. Season vegetables, seafood, and meats with herbs and spices rather than with creamy sauces, butter, or margarine. Try non-fat mayonnaise and fat-free salad dressings. Steam, boil, bake, or microwave vegetables. Roast, bake, or broil meats, poultry, or fish so that fat drips away as it cooks. Use non-stick cookware so added fat is not necessary. Make gravies with de-fatted broth. Substitute egg whites or egg beaters for whole eggs. Substitute liquid butter buds, applesauce or non-fat yogurt for butter or margarine in baking. Choose Sensibly: Fat Intake Recommendations Humans only need a single tablespoon of vegetable oil per day (15 grams) to get their essential FA. Linoleic and alpha-linolenic These are polyunsaturated fats. The average American consumes about 32-38% of their calories from fat (75 grams or 5 tbls.) Over recent years, the percentage of calories from fat has decreased, but, because of increased caloric consumption over these past recent years, we are actually consuming more total grams of fat. Recommendations: No more than 30% of calories from fat, and no more than 7-10% from saturated fat sources, up to 10% from polyunsaturated sources, and up to 20% from monounsaturated sources. Food For Thought….. The text states that the goal is to end up with fewer than 30% of your total day’s calories to come from fat. I wonder if it should not be to try to keep the fat in each individual food from contributing more than 30% of calories. Also, is 30% too high????? I wonder. Choose Sensibly 8. Choose beverages and foods to moderate your intake of sugars. As discussed previously, sugars are classified as simple carbohydrates, whereas starch is defined as a complex carbohydrate. Sugars and starches occur naturally in many foods—including milk, fruits, some vegetables, bread, cereals, and grains. These foods, however, provide many important nutrients. On the other hand, so-called added sugars- supply added calories, but few nutrients. Foods rich in added sugars include things like soft drinks and desserts. Choose Sensibly How Carbonated beverages 8-10 tsp much yogurt 7 tsp sugar 1 cup canned corn 3 tsp is 1 tablespoon ketchup 1 tsp added Glazed donut 6 tsp to this??? 1 choc. Éclair or piece of angel food cake 7 tsp 2 oz. chocolate candy 8 tsp Iced chocolate cake or berry pie 10 tsp 4 oz hard candy 20 tsp Choose Sensibly A sugar by any other name… Read the label to locate hidden sugars in the foods you consume. Sugars are listed by many different names, including brown sugar, corn sweetener, corn syrup, fructose, fruit juice concentrate, glucose or dextrose, high-fructose corn syrup, honey, lactose, maltose, molasses, raw sugar, table sugar, or sucrose, and syrup. If one of these appears near the top of the ingredients list, the food is probably high in added sugars. Choose Sensibly Recommendations: The FGP places foods high in added sugars at the top of the pyramid. Average American intake of added sugars: males-22 tsps., females, 16 tsps. This does not include naturally occuring sugars found in foods such as milk and fruits. The USDA recommendation: 1600 calories/day = no more than 6 tsp/day 2200 calories/day = no more than 12 tsp/day 2800 calories/day = no more than 18 tsp/day Choose Sensibly Rationale: Sugars and starches can both promote tooth decay. Sugars increase serum triglyceride levels. Added calories for little nutrient density. Choose Sensibly 9. Choose and prepare foods with less salt. The human body requires 500 mg Na/day. Average American consumes about 4,000- 6,000 mg/day. High Na intake associated with HTN. USDA recommendation: no more than 2,400 mg/day or about 1 tsp. NaCl/day. Refer to Table 9.4, p. 297 text for sources of salt. Choose Sensibly Tips for reducing salt intake: Read food labels. Choose more fresh fruits and veges. Choose fresh or frozen fish, shellfish, poultry, and meat. They are lower in salt than most canned and processed forms of meats. Reduce salt use during cooking. Substitute herbs and low-Na seasonings. Avoid the salt shaker, and limit use of condiments such as soy sauce, ketchup, mustard, pickles, and olives. Limit intake of foods with visible salt on them, such as snack chips, salted nuts, cracker, etc. Choose Sensibly 10. If you drink alcoholic beverages, do so in moderation. Alcohol supplies calories with very little nutrition. (7 calories/gm). Alcohol is linked with many health problems, birth defects, accidents, violent crimes, and addiction. See list on p. 298 for USDA identified groups that should abstain from alcohol. Choose Sensibly Moderate intake means…… No more than two drinks a day for men, and one drink a day for women. One serving of alcohol, commonly called a ―drink‖ delivers 0.5 ounces of pure alcohol. 12 oz regular beer (150 calories) 5 oz wine (100 calories) 1.5 oz of 80-proof distilled spirits (100 cals) 10 oz of wine cooler (140 calories) See Table 9.5 for BAC and symptoms. 10 Cardinal Sports-Nutrition Principles that are Applicable to the Athlete 1. Prudent diet is the cornerstone 2. Increase total energy intake 3. Keep the dietary carbohydrate intake high (55-70%) during training 4. Drink large amounts of fluid during training and the event 5. Keep a close watch on possible iron deficiency 6. Vitamin and mineral supplements are not needed 7. Protein supplements do not benefit the athlete 8. Rest and emphasize carbohydrates before long endurance events 9. Use of ergogenic aids is unethical 10. Fat loading is not recommended for enhanced performance or health Prudent diet is the cornerstone For all Americans, physically active or not, the ―prudent diet‖ is the recommendation. The ―prudent diet‖ adheres to recommendations from the National Research Council, and the USDA’s Dietary Guidelines for Americans RDA’s provided in text on pages 284- 285. Prudent diet is the cornerstone Dietary practices of athletes Athletes who purposely keep their weight below natural weight for competition tend to have reported caloric intakes that fall way below calculated energy expenditure. Athletes in sports that emphasize leanness (wrestlers, gymnasts, body builders, runners, and ballet dancers) are exceptionally preoccupied with weight and tend to use unhealthy methods for weight control, tend toward eating disorders and demonstrate poor nutrition practices. Protein intake in athletes ranges form 10 – 36% of total calories. Athletes are not much different than the non-athletic population, who also tends to consume nearly double the RDA for protein. Fat intake averages 36% of energy intake in athletes. Power and strength athletes tended to have higher fat intakes than endurance athletes, and this is often associated with the higher protein intake. Carbohydrate provides about 46% of energy consumed by athletes. Tri- athletes tended to have higher carbohydrate intake than the other athletes. Vitamin and mineral intakes tended to be higher than the RDA, because the athletes ate more food than inactive people. There is also widespread use of supplements in athletes. However, sports emphasizing leanness were found to consume insufficient quantities of vitamins and minerals. In general, the quality of the athletes diet is somewhat similar to that of the general population. Increase total energy intake If a person is of normal body weight, and they exercise regularly, that person’s energy consumption will need to be higher than that of the average sedentary individual to maintain body weight. The amount and intensity of training and body size are the chief determinants of the energy requirements of the athlete. See Table 9.7, p. 301 Keep the dietary carbohydrate intake high (55-70%) during training There are several basic principles regarding the relationship between exercise and dietary carbohydrate and muscle glycogen. Body glycogen stores play an important role in hard exercise (70-85% of VO2 max) that is either prolonged and continuous or of an extended intermittent mixed anaerobic-aerobic nature. There are limited CHO stores in the body, and the body adapts in various ways to maximize its use of these stores. Exhaustion during prolonged, hard exercise is tied to low muscle glycogen levels. When muscle and liver glycogen stores are low, a high work output cannot be maintained. ―Hitting the Wall‖ During the first hour of hard exercise, most CHO and fat come from within the muscle. As exercise continues beyond one hour, more demand is placed upon adipose tissue fat fuel sources and blood glucose as muscle glycogen levels begin to be depleted. The longer the exercise, the greater the need for glucose from the liver. During training, muscle glycogen stores undergo rapid day-to-day fluctuation. Rapid restoration of muscle glycogen stores is essential to those athletes that compete or train repeatedly on same or consecutive days. Glycemic index—which foods to choose pre, during and post event/training. See Box 9.5, p. 309. Recommendation: athletes in heavy training should consume a diet of close to 70% CHO, or about 525 grams per 3000 calories). This will restore muscle glycogen within 24 hours, enabling the athlete to continue heavy training. This is especially important after race events and long, intense training bouts. See table 9.10 for listing of high CHO foods. Drink large amounts of fluid during training and the event As little as a 2% drop in body weight caused by water loss (primarily from sweat) can reduce exercise capacity. If you are thirsty, you are already dehydrated. Recommendation: Drink 2 cups of water immediately before exercise, 1 cup every 15 minutes during exercise, and then 2 more cups after the session. If exercising longer than one hour, then consider carbohydrate and sodium drinks. Loss of body water from sweating beyond 2% of body weight will significantly impair endurance capacity, through elevation of body temperature and decreased cardiac output. When sweat output exceeds water intake, both intracellular and extra-cellular water levels fall, and plasma volume decreases. This results in an increase in body temperature, a decrease in the ability of the heart to pump blood, and a decrease in endurance performance. Intracellular fluid accounts for 67%, Interstitial (between cells) fluid accounts for 27% and plasma volume accounts for 6% of an average 70 kg individual with 42 liters of body water. (60% of body weight.) Acclimatization process occurs as people train in the heat. The individual will have a higher plasma volume and sweat glands will produce more sweat earlier in the exercise session, with less loss of sodium. Body temp and HR do not rise as strongly in those who are acclimatized. When the body loses water during prolonged exercise, and it is not replenished, there is a gradual decrease in heart stroke volume, and a corresponding increase in heart rate. Box 9.6, p. 316- ACSM position stand on fluid replacement. Should electrolytes and carbohydrates be used during exercise? When exercise exceeds one hour, the exercisers fluid, electrolyte, and carbohydrate requirements can be met simultaneously by ingesting 600-1200 ml/hour of a solution containing 4-8% CHO and 0.5- 0.7 grams of sodium per liter. Keep a close watch on possible iron deficiency Some athletes, especially females, may be prone to iron deficiency. Recommendation is to not routinely take iron supplements without medical supervision, but to increase iron consumption by eating foods high in iron. Heme-Fe and non-heme Fe. Vitamin C See table 9.15, p. 322 for foods with various iron contents. Vitamin and mineral supplements are not needed Most studies show that the intake of major vitamins and minerals by people who exercise is above recommended levels. The increase in food eaten by exercisers provides the extra vitamins and minerals, particularly if the diet consists of a high-carbohydrate, moderate protein, low-fat menu. Even though many coaches and fitness journals urge supplementation to boost or maximize performance, the ACSM, the ADA, and Dietitians of Canada have made a statement that no vitamin or mineral supplements are required if an athlete is consuming adequate energy from a variety of foods. The AMA, the ADA, the American institute of nutrition, the food and nutrition board, and the national council against health fraud, have submitted formal statements to the effect that there are no demonstrated benefits of self-supplementation beyond the RDA, except in special cases. submitted a formal statement to the effect that there are no demonstrated benefits of self-supplementation beyond the RDA, except in special cases. Recommendation: The best nutritional strategy for promotion optimal health and reducing the risk of chronic disease is to obtain adequate nutrients from a wide variety of foods. High intake of vitamins and minerals even could be problematic, especially with the fat soluble vitamins A,D,E, and K. Furthermore, excess of one nutrient can cause a deficiency in another nutrient. Research shows that between 50 and 80% of elite athletes use vitamin and mineral supplements on a regular basis. Protein supplements do not benefit the athlete Many people who exercise, especially weight lifters, feel that consumption of high-protein foods and protein supplements is necessary to build muscle mass. The average sedentary person has been advised to consume 0.8 gram of protein per kilogram of body weight. Research is showing that highly active people may need 50-125% more than this because 5-15% of the energy required for long endurance exercise or weight lifting comes from protein, and extra protein is needed for muscle protein synthesis. However, most experts feel that the traditional food supply provides all of the protein needed, even for the athletes during active muscle-building phases—supplements are not needed. The American Dietetic Association has advised that endurance athletes take in 1.2-1.4 g/kg protein daily. However, most endurance athletes are already getting this much protein and do not need to supplement their diets with protein powder or concern themselves with eating high-protein foods. Most strength and power athletes can enhance muscle development when dietary protein intake ranges between 1.6 and 1.7 g/kg. There is no evidence that very high protein intakes (>2g/kg/day) are either necessary or beneficial. There is little scientific evidence that amino acid supplementation enhances the physiological responses to strength training when adequate diets are consumed. See Table 9.17 for a list of the protein content of common foods. Refer to Box 9.7, p. 328 for special issues for Vegetarians. Rest and emphasize carbohydrates before long endurance events When an event lasts longer than 60-90 minutes, it is recommended to taper off the exercise gradually during the week before the event, while consuming more than 70% CHO during the 3 days before the event. If the event is less than 60 minutes, carbohydrate loading is not necessary. See page 329 for CHO loading. For the pre-event meal, most sports-nutrition experts advise one or two glasses of water, followed within 20-30 minutes by a light (500-800 kcal) meal of rapidly digestible, low-fiber starch (cream of wheat hot cereal, white bread, bagels, pasta, refined cereals, low glycemic index foods). The food should be consumed 3-5 hours before the event, so the stomach will be empty at the time of competition to avoid abdominal fullness or cramping. The use of proteins, fats, known gas-forming foods, high-fiber foods, and foods known to act as laxatives is not recommended. Use of ergogenic aids is unethical Five categories of ergogenic aids: Nutritional aids Pharmacological aids Physiological aids Psychological aids Mechanical aids See Table 9.18, p. 332 for products, claims, and fact on their ergogenic ability. Fat loading is not recommended for enhanced performance or health Athletes have no guarantee of protection from heart disease unless they continue prudent habits of exercise and diet after their days of competition are over. Even during heavy training, a diet high in saturated fats can raise serum cholesterol to high levels. Regular endurance exercise will not fully negate bad nutritional habits. Nearly all studies have shown that high-fat diets (about 70% of total energy) for several days prior to endurance exercise significantly decrease body carbohydrate stores, reducing endurance time dramatically. Although the relative contribution of fat is increased, performance is impaired due to low muscle glycogen. Summary Refer to page 342 for a summary of the ten Principles outlined in the text.
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