CH-9-10 Water and Minerals – Wardlaw’s Contemporary Nutrition : Chapter Notes

This Document Contains Chapters 9 to 10 CHAPTER 9 WATER AND MINERALS OVERVIEW This chapter discusses water, major minerals, and trace minerals. The nature and general properties of water, specific functions, needs, and thirst are addressed. Mineral bioavailability and nutrient interactions are explored. Major minerals such as sodium, potassium, chloride, calcium, phosphorus, and magnesium, are discussed in terms of their absorption, functions, food sources, requirements, and health implications (i.e., deficiency and toxicity). Trace minerals, including iron, zinc, selenium, iodide, copper, fluoride, chromium, manganese, and molybdenum are covered. Two other vital trace minerals are briefly discussed. Specific functions, food sources, deficiency and toxicity symptoms, and requirements or recommendations for intake are given for each of the trace minerals. The Nutrition and Your Health section discusses minerals and hypertension. KEY TERMS Aldosterone Amniotic fluid Anemia Angiotensin Antidiuretic hormone (ADH) Bioavailability Bisphosphonates Bone mass Bone mineral density Cellular differentiation Ceruloplasmin Cofactor Congenital hypothyroidism Cortical bone Dehydration Diuretic Dual energy X-ray absorptiometry (DEXA) Electrolytes Extracellular fluid Gene expression Goiter Hard water Hematocrit Heme iron Hemochromatosis Hemoglobin Hypertension Hyponatremia Intracellular fluid Kyphosis Major Mineral Metabolic water Mineral Mottling Myoglobin Nonheme iron Osmosis Osteopenia Oxalic acid (oxalate) Parathyroid hormone (PTH) Phytic acid (phytate) Primary hypertension Secondary hypertension Soft water Solvent Tetany Trabecular bone Trace Mineral Type 1 osteoporosis Type 2 osteoporosis Ultratrace mineral Urea Water intoxication Wilson's disease STUDENT LEARNING OUTCOMES Chapter 9 is designed to allow you to: 9.1 Understand the functions of water in the body, the regulation of fluid balance, and the health consequences of fluid imbalance (i.e., dehydration); list the recommended intakes and sources of water. 9.2 Describe the general characteristics of the major and trace minerals, the general process of mineral absorption and storage, the dangers of mineral toxicities, and ways to preserve minerals in foods. 9.3 Describe the roles of sodium in controlling fluid balance, acid-base balance, and nerve impulse transmission, and list its dietary sources and requirements, as well as the dangers of exceeding sodium recommendations. 9.4 List the functions, dietary sources, and requirements of potassium, as well as the dangers of getting too much potassium. 9.5 List the functions of chloride, as well as its dietary sources and requirements. 9.6 List the dietary sources and requirements of calcium and describe its role in bone growth, maintenance and repair, as well as the process of osteoporosis development and prevention. 9.7 Describe the functions, dietary requirements, and sources of phosphorus, as well as the benefit of avoiding too much phosphorus. 9.8 List magnesium functions and sources, as well as the dangers of magnesium toxicity from nonfood sources. 9.9 Describe the functions of iron in the maintenance of blood health, and list its sources, dietary requirements, and deficiency and toxicity problems. 9.10 Describe the functions of zinc, including its role in immune function, as well as its food sources, dietary requirements, and signs and symptoms of deficiency and toxicity. 9.11 Summarize the functions of selenium, and describe its dietary requirements, food sources, and symptoms of deficiency, as well as the dangers of toxicity from supplements. 9.12 Describe the functions of iodine in thyroid metabolism, and list its sources, dietary requirements, and problems of deficiency and toxicity. 9.13 Describe the functions of copper and is potential for toxicity, and list its sources, dietary requirements, and conditions that can lead to a deficiency. 9.14 Describe the role of fluoride in tooth development and bone health and its primary sources, as well as recommendations for use and problems of toxicity. 9.15 Describe the functions of chromium in glucose metabolism, and list its sources, dietary requirements, and deficiency symptoms. 9.16 Describe the functions of manganese and molybdenum, and understand how to get enough from dietary sources. 9.17 Describe the factors that can contribute to the development of hypertension. LECTURE OUTLINE 9.1 Water A. Overview 1. 50% to 70% of the body's weight (see Fig. 9-2) 2. Lean tissue: 73% water 3. Fat tissue: 20% water 4. Water is a solvent dissolving many body components 5. Water provides medium for chemical reactions 6. Water participates in many metabolic reactions 7. No storage; humans can survive only a few days without water B. Water in the Body—Intracellular and Extracellular Fluid 1. Cell membranes are permeable to water; moves by osmosis 2. Intracellular: fluid within cells (see Fig. 9-3) 3. Extracellular: fluid outside cells (see Fig. 9-3) 4. Ion or electrolyte concentrations control the amount of water in intracellular and extracellular fluid (see Fig. 9-4) a. Ions are electrically charged molecules that attract water b. Chloride, potassium, sodium, phosphate, magnesium, and calcium are all ions c. Positive ions pair with negative ions d. Intracellular fluid is dependent on potassium and phosphate concentrations e. Extracellular fluid is dependent on sodium and chloride C. Water Is the Universal Solvent 1. Overview a. Water is ideal transport vehicle for nutrients and wastes b. Water is ideal medium for many chemical reactions of human metabolism. 2. Water transports nutrients and wastes. a. Most unused substances in the body can dissolve in water and exit in the urine 1) Urea is the product created to excrete nitrogen when excess protein is consumed 2) Excess sodium is also excreted in the urine 3) Generally, the amount of urine we excrete is determined by the amount of sodium and protein we need to excrete b. Healthy urine output: 1 L or more per day 1) Less than 500 ml (2 c) forces kidneys to excessively concentrate the urine 2) Observe the color of urine to determine if it is too concentrated 3) Urine should be clear or pale yellow 4) Heavy ion concentration in urine increases risk of kidney stones 3. Water is a medium for chemical reactions. a. Water is a by-product of metabolism of energy from macronutrients b. Metabolic water (1 cup or more per day) contributes to maintenance of fluid balance in the body D. Water Contributes to Body Temperature Regulation 1. Water changes temperature slowly because its molecules are attracted to each other; much energy is required to separate the molecules 2. Perspiration (see Fig. 9-5) a. Evaporation releases heat and cools the skin b. Perspiration is the primary way to prevent body heat from rising 3. Fever increases calorie needs 4. 60% of chemical energy in food is converted to body heat; 40% is converted into forms of energy cells can use (eventually converted to heat) E. Water Moistens, Lubricates, and Cushions 1. Helps form lubricants found in knees and other body joints 2. Basis for saliva, bile, and amniotic fluid F. The Water Balancing Act 1. Water intake (see Fig. 9-6) a. Adequate Intake for total water intake: including fluid from food and beverages 1) Women: 2.7 L (11 c) 2) Men: 3.7 L (15 c) b. Fluid intake aside from food should be 1) Women: 2.2 L (9 c) 2) Men: 3 L (11 c) 3) Includes water, juice, soda, coffee, tea 4) Coffee, tea, soda and other beverages containing caffeine increase urine output, but not all of the fluid is lost c. Foods supply water (see Fig. 9-7) d. Water as a by-product of metabolism (250–350 ml/d) 2. Water Output (see Fig. 9-6) a. Urine production: 500 or more ml b. Lungs: 250–350 ml c. Colon: 100–200 ml d. Skin: 450–1900 ml e. Above values are estimates affected by altitude, caffeine, alcohol, and humidity 3. Fluid Conservation a. Body conserves water (see Fig. 9-8) b. Antidiuretic hormone (ADH) released by pituitary gland forces kidneys to conserve water by reducing urine output c. As blood volume decreases, blood pressure falls, triggering release of an enzyme that activates angiotensin and eventually aldosterone, which signals kidneys to retain sodium and therefore water d. Despite mechanisms for water conservation, losses continue via feces, skin, and lungs 4. Dehydration (see Fig. 9-9) a. Thirst kicks in when body water falls by 1% to 2% (even this amount can cause fatigue) b. 4% loss of body weight as water: muscular strength and endurance compromised c. 10% to 12% reduction of body weight: decreased heat tolerance and weakness d. 20% reduction: coma and death e. Simplest way to determine if water intake is adequate is to observe urine color (see Fig. 9-10) 5. Is thirst a good indicator of hydration status? a. Thirst mechanism is not always reliable b. Athletes 1) Weigh before and after training sessions to determine their rate of water loss and thus water needs 2) Drink 2–3 cups of water per pound lost c. Others who have greater water needs 1) Ill children 2) Older persons 3) Infants 6. Can a person consume too much water? a. An amount above what the kidneys can excrete can cause low blood concentrations of electrolytes (especially sodium, leading to hypnatremia) b. Excessive amounts would be many quarts each day c. Blurred vision can result G. Sources of Water 1. What is the difference between hard and soft water? a. Hard water contains higher levels of calcium and magnesium b. Soft water is higher in sodium which replaces the calcium and magnesium 2. Is bottled water healthier than tap water? a. Bottled water is an expensive option; often obtained from municipal water supplies b. Obtain information about water safety 1) Ask municipal water department for results of recent water safety tests 2) Local testing laboratory 3) State health department 4) EPA c. Limiting lead exposure 1) Let cold water run for a minute 2) Do not use hot tap water for food preparation d. Plastic may pose threat to health 1) Fresh and new bottle is best 2) Chemicals that make up plastic break down over time 3) Temperature, age of bottle, acidity of contents, and type of plastic are factors in safety e. Table 9-1 lists several guidelines to ensure safety of bottled water 9.2 Minerals—Essential Elements for Health A. Overview 1. Table salt is composed of 40% sodium and 60% chloride 2. Roles: cofactors, nerve impulse transfer, growth and development, water balance, component of body compounds 3. Categorized by body requirements (see Fig. 9-11) a. Major: require > 100 mg/d (1/50 teaspoon) b. Trace: require < 100 mg/d B. Absorption and Storage of Minerals in the Body 1. Bioavailability—the capabilities of our body to absorb and use minerals in our food 2. Fiber-mineral interactions a. Phytic acid and oxalic acid b. High-fiber diets (greater than 25–38 grams per day) can decrease the absorption of iron, zinc, and probably other minerals c. Yeast used in bread making releases enzymes that break the bonds between the minerals and phytic acid 3. Mineral-mineral interactions a. Minerals with similar size and charge compete with one another for absorption (e.g., magnesium, copper, iron, and calcium) b. Taking excess zinc can decrease copper absorption c. Avoid mineral supplements unless specifically warranted by medical condition 4. Vitamin-mineral interactions a. Vitamins may enhance mineral absorption 1) Vitamin C enhances absorption of iron 2) Vitamin D enhances absorption of calcium b. Vitamins may require minerals for biological activity: thiamin coenzyme requires magnesium or manganese C. Mineral Toxicities 1. Excess mineral intake can lead to toxicity 2. For some trace minerals (e.g., iron and copper), the gap between need and toxicity is small 3. Mineral supplements exceeding 100% of the DV should be taken only under a physician's supervision 4. Doses should not exceed the UL on a long term basis 5. Contamination of supplements by lead is a risk; use only brands approved by U.S. Pharmacopeia D. Preservation of Minerals in Foods 1. Food composition tables generally do not reflect bioavailability (see Fig. 9-12) 2. Minerals from animal sources are absorbed better than from plants because fewer binders and dietary fibers are present to hinder absorption 3. Minerals from plant sources a. May be bound by dietary fibers (e.g., only 5% of calcium in spinach is absorbed because oxalic acid in spinach binds the calcium) b. Depends on mineral content of soil in which plants were grown 4. Effect of refining a. Decreases mineral content, especially of iron, zinc, copper, and selenium b. Enrichment process adds back one mineral only: iron 9.3 Sodium (Na) A. Functions of Sodium 1. Fluid balance: water retention in extracellular fluid 2. Nerve impulse conduction 3. Aids absorption of some nutrients (e.g., glucose) B. Sodium Deficiency 1. Rare, but may result from low dietary intake or increased losses through sweat, vomiting, or diarrhea 2. Consequences a. Cramps b. Dizziness c. Shock d. Coma 3. Vulnerable populations: endurance athletes and others who sweat excessively C. Getting Enough Sodium 1. Sodium sources (see Fig. 9-13) a. Salt in cooking and at the table contributes about 10% b. 80% added in food manufacturing or restaurants 1) White bread and rolls 2) Cheese 3) Luncheon meats and hot dogs 4) Foods with tomato sauce 5) Salted snack foods 6) Potato chips and French fries 7) Sauces and gravies c. If we ate only unprocessed foods we would consume about 500 mg/d 2. Absorption: body absorbs almost all consumed sodium 3. Recommendations a. AI: 1500 mg/d (lower for older adults) b. DV: 2400 mg c. Dietary Guidelines: 1) General population: consume <2300 mg/d; choose and prepare foods with little salt 2) People with hypertension, blacks, and middle-aged and older adults: 500 milligrams at one time for maximal absorption of calcium and to avoid inhibiting absorption of other minerals 1) Zinc 2) Iron d. To limit the potential for contamination by lead and/or aluminum, avoid supplements derived from bone meal, dolomite, and oyster shells e. Look for USP label to limit risk for contaminants f. Dietary versus supplemental sources 1) Difficulty adhering to supplement regimen 2) Foods also supply other vitamins, minerals, phytochemicals, and fats 3) Foods present low risk of toxicity g. Vitamin D and Calcium Supplementation to Prevent Fractures report (February 2013) 1) Insufficient evidence to determine whether vitamin D and calcium supplements can prevent fractures in men and women who have not yet gone through menopause 2) Insufficient evidence to determine if Vitamin D and calcium supplementation greater than 400 IU (D) and 1000 mg (Ca) can prevent fractures in noninstitutionalized postmenopausal women 3) There is enough evidence to recommend against daily supplementation with 400 IU or less of vitamin D and 1000 mg or less of calcium for the primary prevention of fractures in noninstitutionalized postmenopausal women h. Side effects 1) Gas 2) Bloating 3) Constipation 9.7 Phosphorus (P) A. Functions of Phosphorus 1. Component of enzymes 2. Component of DNA 3. Component of all cell membranes (phospholipids) 4. Component of bone (85% of body phosphorus) B. Phosphorus Deficiency 1. Uncommon 2. Consequences: bone loss 3. Vulnerable populations a. Older adults with nutrient-poor diets b. Preterm infants c. Vegans d. Alcoholics e. People with long-term diarrhea C. Getting Enough Phosphorus 1. Phosphorous sources (see Fig. 9-22) a. Widely available in foods b. Food sources 1) Milk 2) Cheese 3) Bread 4) Meat 5) Breakfast cereals 6) Bran 7) Eggs 8) Nuts 9) Fish c. 20% to 30% from food additives: baked goods, cheeses, processed meats, and soft drinks 2. Absorption a. 70% is absorbed b. Vitamin D enhances absorption 3. Recommendations a. RDA: 700 mg/d b. DV: 1000 mg c. Average intake: 1000–1600 mg/d D. Avoiding Too Much Phosphorus 1. Consequences a. May impair kidney function b. Too much phosphorus (usually from too much soda) coupled with inadequate calcium leads to bone loss 2. UL: 3 to 4 g/d 9.8 Magnesium (Mg) A. Functions of Magnesium 1. Nerve and heart functions a. Decreases blood pressure b. Prevents heart rhythm abnormalities 2. Maintenance of bone; 60% of body's magnesium is in bone 3. Cofactor for over 300 enzymes B. Deficiency 1. Develops slowly 2. Consequences a. Irregular heartbeat b. Weakness c. Muscle pain d. Disorientation e. Seizures 3. Vulnerable populations a. Diuretic users b. People who perspire heavily c. People with long-term vomiting and diarrhea d. Alcoholics C. Getting Enough Magnesium 1. Magnesium sources (see Fig. 9-23) a. Whole grains b. Broccoli c. Squash d. Beans e. Nuts and seeds f. Milk g. Meats h. Hard tap water i. Coffee 2. Recommendations a. RDA 1) Males: 400 mg/d 2) Females: 310 mg/d b. DV: 400 mg c. Average intake 1) Males: 320 mg/d 2) Females: 220 mg/d d. Absorption: 1) 40% to 60% absorbed from diet 2) Diets high in phosphorus or fiber limit absorption 3) Diets low in protein limit absorption D. Avoiding Too Much Magnesium 1. Consequences: diarrhea 2. UL: 350 mg/d (of non-food sources) 3. Toxicity symptoms only seen with overuse of non-food sources of magnesium (e.g., antacids, supplements, and laxatives) 9.9 Iron (Fe) A. Functions of iron 1. Component of hemoglobin and myoglobin 2. Oxygen and carbon dioxide transport 3. Component of enzymes and some proteins for energy production 4. Brain and immune function 5. Drug detoxification in liver 6. Bone health B. Iron Deficiency 1. One of the most common deficiencies (30% of world population is anemic; half of those cases are due to iron deficiency) 2. Iron deficiency anemia a. Stage 1: Iron stores become depleted b. Stage 2: The amount of iron in transferrin is depleted; some physiological impairment occurs. Heme production is decreased, and activities of enzymes that require iron as a cofactor are limited. c. Stage 3: Red blood cells are small (microcytic), pale (hypochromic), and reduced in number; oxygen-carrying capacity of red blood cells declines 3. Symptoms of anemia a. Decreased oxygen-carrying capacity b. Pale skin c. Fatigue, apathy, decreased learning ability/work performance d. Poor temperature regulation e. Loss of appetite f. Low percent RBC (hematocrit) or low hemoglobin concentration 4. High risk categories a. Infants b. Preschoolers c. Puberty, both men and women d. Childbearing years because of menstruation e. Pregnancy f. Blood loss from ulcers, colon cancer, or hemorrhoids g. Athletes h. Vegetarians 5. Once anemia has developed, iron supplements are the only reliable cure C. Absorption and Distribution of Iron 1. Iron absorption depends on the following factors (Table 9-7) a. Person's iron status b. Form in food c. Acidity of GI tract d. Dietary components consumed with iron-containing foods e. Body's need (most important factor) 2. Controlling absorption is important because iron is stored and not easily eliminated 3. Form influences how much is absorbed a. Heme iron 1) From animal flesh 2) Best source of iron, absorbed 2–3 times more efficiently than nonheme iron 3) Hemoglobin and myoglobin b. Nonheme iron; elemental iron 1) Animal flesh, eggs, milk, vegetables, grains, and other plant foods 2) Nonheme absorbed better if consumed with heme iron D. Getting Enough Iron 1. Iron sources (Fig. 9-24) a. Animal products are best sources b. Iron supplements c. Grain products because of enrichment d. Iron-fortified formulas and cereals for children e. Milk is a poor source f. Body needs for iron are the greatest influence on efficiency of absorption 1) Factors that increase iron absorption: i. Iron-binding protein not saturated (low iron in blood) ii. Up to 20% absorbed in deficiency iii. Vitamin C (75 mg) increases absorption of nonheme iron iv. More absorbed during pregnancy and growth 2) Factors that decrease iron absorption i. Phytic acid and oxalic acid ii. Tannins (polyphenols) in tea iii. Zinc supplements 2. Recommendations a. RDA 1) Males: 8 mg/d 2) Females 19 to 50 years old: 18 mg/d b. DV: 18 mg c. Average intake in American diet 1) Males: 18 mg/d 2) Females: 13 mg/d E. Avoiding Too Much Iron 1. Upper level for iron a. May be caused by repeated blood transfusions b. Consequences 1) Stomach irritation 2) Single 60 mg dose can be life threatening to infant c. UL: 45 mg/d d. Hemochromatosis 1) Genetic disease that leads to increased iron absorption 2) Iron deposits in heart, muscles, and pancreas can lead to severe organ damage 3) Problems usually do not surface until late in adulthood, but early testing (transferrin saturation and ferritin) could identify the problem early 4) Approximately 1 in 250 North Americans has two copies of the gene for hemochromatosis e. Iron supplements must carry warning label about toxicity; tablets with > 30 mg must be individually wrapped 9.10 Zinc (Zn) A. Overview 1. First recognized in early 1960s in Egypt and Iran because of diet of unleavened bread and little animal protein; unleavened bread high in phytic acid 2. Yeast breaks down phytic acid, making zinc in leavened products more bioavailable 3. Causes growth retardation and poor sexual development (see Fig. 9-25) B. Functions of zinc 1. Cofactor for over 200 enzymes 2. DNA synthesis 3. Protein metabolism 4. Wound healing 5. Growth 6. Immune function 7. Proper bone and sexual organ development 8. Storage, release, and function of insulin 9. Cell membrane structure and function 10. Aids in the prevention of oxidative cell damage, component of superoxide dismutase 11. Slows progression of macular degeneration 12. Reduced risk for some forms of cancer C. Zinc Deficiency 1. Adult symptoms a. Acne-like rash b. Diarrhea c. Lack of appetite d. Reduced sense of taste and smell e. Hair loss f. Poor growth g. Impaired sexual development h. Hampered learning ability 2. In children and adolescents, zinc deficiency leads to impairment of growth and sexual development, as well as learning disabilities. D. Getting Enough Zinc 1. Zinc sources a. Animal sources are best absorbed, including beef, milk, poultry, and bread b. Absorption from plant sources, including whole grains, peanuts, legumes, is hampered by the presence of phytic acid c. Breakfast cereals are often fortified with zinc d. Figure 9-26 presents sources of zinc e. Vulnerable to poor intake 1) Women 2) Poor children 3) Vegans 4) Older adults 5) Alcoholics 2. Absorption a. 40% absorbed b. High calcium intake decreases absorption c. Zinc competes with iron and copper for absorption 3. Recommendations a. RDA 1) Males: 11 mg/d 2) Females: 8 mg/d b. DV: 15 mg c. Average intake: 10–14 mg/d E. Avoiding Too Much Zinc 1. Consequences a. May increase risk for prostate cancer b. Inhibits copper metabolism c. Diarrhea, cramps d. Nausea, vomiting e. Depressed immune system function 2. UL: 40 mg/d 3. If on high dose to slow macular degeneration, should take 2 mg/d copper supplement 9.11 Selenium (Se) A. Functions of Selenium 1. Antioxidant: role in glutathione peroxidase 2. Contributes to thyroid hormone metabolism 3. May aid in cancer prevention, but research is ongoing B. Selenium Deficiency 1. Consequences a. Muscle pain b. Wasting c. Form of heart disease 2. Vulnerable populations C. Getting Enough Selenium 1. Selenium sources (Fig. 9-27) a. Fish b. Meats c. Eggs d. Organ meats e. Shellfish f. Grain and seeds grown in soil containing selenium 2. Recommendations a. RDA: 55 mcg/d b. DV: 70 mcg c. Average intake: 70 mcg/d D. Avoiding Too Much Selenium 1. Consequences: hair loss 2. UL: 400 mcg/d 9.12 Iodide (I) A. Overview 1. Great Lakes region has low soil content, children given supplement in 1920 prevented goiters 2. Led to addition of iodine to salt 3. Functions of iodide a. Thyroid hormone requires tyrosine and iodide b. Regulate metabolic rate c. Promote growth and development B. Iodide Deficiency 1. Consequences a. Goiter 1) Thyroid gland enlarges as it attempts to take up more iodide from the blood stream 2) Painless but can put pressure on trachea 3) Once formed, it doesn't shrink significantly b. Congenital hypothyroidism in child: from maternal deficiency during pregnancy 2. Vulnerable populations: people who live in regions where soil iodide content is low and salt is not fortified C. Getting Enough Iodide 1. Iodide sources (Fig. 9-28) a. Food sources 1) Iodized salt 2) Saltwater fish 3) Seafood 4) Dairy products 5) Grain products b. Fast food restaurants and dairies use as sterilizer c. Bakeries use as dough conditioner 2. Requirements a. RDA: 150 mcg/d (1/2 tsp iodized salt) b. DV: 150 mcg/d D. Avoiding Too Much Iodide 1. Consequences: inhibited thyroid hormone synthesis 2. UL: 1.1 mg/d 3. Toxicity is seen in populations consuming a lot of seaweed (iodide intake is 60–130 times the RDA) 9.13 Copper (Cu) A. Overview 1. Component of blood 2. Ceruloplasmin is the name of the protein that carries most copper in blood B. Functions of Copper 1. Iron metabolism a. Formation of hemoglobin, transport of iron b. Copper-containing enzyme releases iron from storage 2. Cross-connections in connective tissue proteins 3. Cofactor for antioxidant enzymes 4. Immune system functions 5. Blood clotting 6. Blood lipoprotein metabolism C. Copper Deficiency 1. Symptoms a. Anemia b. Low white blood cell count c. Bone loss d. Poor growth e. Some forms of cardiovascular disease 2. Groups at risk of deficiency a. Premature infants b. Infants recovering from semi-starvation on milk dominated diet c. People recovering from intestinal surgery d. Those who consume too much zinc D. Getting Enough Copper 1. Copper sources (Fig. 9-29) a. Liver b. Seafood c. Cocoa d. Legumes e. Nuts f. Dried fruits g. Whole grains 2. Absorption a. Higher intake leads to lower efficiency of absorption b. Absorb 12–75% c. Absorb in stomach and small intestines d. Phytates, fiber, zinc, and iron interfere with copper absorption e. Form of copper in supplements is not readily absorbed; better to consume food sources 3. Recommendations a. RDA: 900 mcg/d b. DV: 2 mg c. Average intake: 1–1.6 mg/d E. Avoiding Too Much Copper 1. Consequences a. Vomiting b. Liver toxicity 2. UL: 10 mg/d 3. Toxicity can occur from a single 10 mg dose 4. Wilson's Disease: genetic disease in which the liver cannot synthesize cerloplasmin 9.14 Fluoride (F) A. Overview 1. Fluorine is a poisonous gas 2. Lower rates of dental caries observed in areas of southwestern United States, where fluoride is naturally high in water supply 3. Fluoridation of water in parts of United States began in 1945 4. Water fluoridation decreases dental caries by 40%–60% 5. If water supply contains less than 1 part fluoride per million parts of water, topical fluoride treatment may be warranted B. Functions of Fluoride 1. Strengthens the structure of bones and teeth 2. Aids in synthesis of tooth enamel during tooth development 3. Inhibits growth of bacteria that cause dental caries 4. Possible treatment for severe osteoporosis C. Getting Enough Fluoride 1. Fluoride sources a. Food sources 1) Tea 2) Seaweed 3) Seafood 4) Fluoridated water (not bottled water) b. Topical sources include toothpaste and fluoride treatments by dentists 2. Requirements a. AI: 3.1 to 3.8 mg/d for adults b. Provides resistance to dental caries D. Avoiding Too Much Fluoride 1. Fluorosis 2. Consequences a. Mottling (white or yellow spots on teeth) 1) Can occur from swallowing toothpaste also 2) Mottling occurs during tooth development, cannot occur in adulthood b. Skeletal and tooth damage 3. UL a. 1.3–2.2 mg/d for young children b. 10 mg/d for children over 9 9.15 Chromium (Cr) A. Functions of Chromium 1. Primary known function is to aid insulin function 2. May also be involved in enzymes that control cholesterol synthesis B. Chromium Deficiency 1. High serum cholesterol and triglyceride levels 2. Poor blood glucose control 3. Possibly increased risk of type 2 diabetes C. Getting Enough Chromium 1. Chromium sources a. Food sources 1) Egg yolks 2) Bran 3) Organ and other meats 4) Mushrooms 5) Nuts 6) Yeast b. Dependent on soil content c. Difficult to measure; many food composition tables do not provide information on chromium content d. Absorption is low 2. Requirements a. AI: 25 to 35 mcg/d b. DV: 120 mcg c. Average intakes: 30 mcg/d (may be higher) 3. Toxicity a. Liver damage and lung cancer result from environmental exposure to chromium-containing industrial waste and paint b. No UL set; toxicity from foods has not been observed c. Avoid supplements containing greater than the DV 9.16 Other Trace Minerals A. Manganese (Mn) 1. Functions a. Cofactor of enzymes used in carbohydrate metabolism b. Indirect antioxidant as part of a form of superoxide dismutase c. Bone formation 2. Sources a. Nuts b. Rice c. Oats d. Whole grains e. Beans f. Leafy vegetables 3. Requirements a. AI: 1.8 to 2.3 mg/d b. DV: 2 mg c. Average intakes meet AI 4. No known deficiency 5. Upper level for manganese a. Consequences: nerve damage b. UL: 11 mg/d B. Molybdenum (Mo) 1. Functions a. Interacts with iron and copper b. Cofactor of enzymes 2. Sources a. Milk products b. Beans c. Whole grains d. Nuts 3. Requirements a. RDA: 45 mcg/d b. DV: 75 mcg c. Average intakes: 75–110 mcg 4. Deficiency a. Only observed after treatment with molybdenum-free TPN b. Consequences 1) Increased heart and respiration rate 2) Night blindness 3) Confusion 4) Edema 5) Weakness 5. Upper level for molybdenum a. Consequences (in laboratory animals) 1) Weight loss 2) Decreased growth b. Upper Level: 2 mg/d Nutrition and Your Health: Minerals and Hypertension A. Overview 1. One in 5 adults has hypertension 2. Systolic blood pressure a. Higher number b. Pressure in the arteries when the heart is contracting c. Optimal is 120 mm Hg 3. Diastolic blood pressure a. Lower number b. Pressure in the arteries when the heart is at rest c. Optimal is 80 mm Hg 4. Hypertension: >139/>89 mm Hg 5. Primary hypertension: no clear-cut cause 6. Secondary hypertension a. Kidney disease b. Sleep apnea 7. African Americans have higher risk than Caucasians; develop hypertension earlier in life 8. Silent disorder, usually no signs, get checked often B. Why Control Blood Pressure? 1. Prevent complications a. Cardiovascular disease b. Kidney disease c. Strokes d. Declines in brain function e. Poor circulation f. Vision problems g. Sudden death 2. Smoking and elevated blood lipids increase risk even more C. Contributors to Hypertension 1. Risk factors a. Family history b. Age c. Overweight (increases risk 6X) d. Inactivity e. Excessive alcohol intake 2. Atherosclerosis a. Build-up of plaque in arteries reduces blood vessel flexibility b. Blood pressure remains elevated c. Plaque decreases blood supply to kidneys, thus decreasing their ability to control blood volume 3. Excess weight a. Additional blood vessels develop to support excess tissue b. Increased workload on heart  increased blood pressure c. Elevated insulin increases sodium retention and accelerates atherosclerosis 4. Inactivity 5. Excess alcohol intake 6. Sodium sensitivity a. Excess salt leads to fluid retention by kidney b. Increased blood volume increases workload on heart D. Other Minerals and Blood Pressure 1. Diets rich in calcium, potassium, and magnesium and low in sodium can decrease blood pressure 2. Diet rich in low-fat dairy products, fruits and vegetables, whole grains, and some nuts (such as the DASH diet detailed in Table 9-9) decrease risk of hypertension and stroke E. Medications to Treat Hypertension 1. Diuretics (water pills) 2. Slow heart rate 3. Relax blood vessels F. Prevention of Hypertension (Figure 9-31) 1. Loss of excess weight 2. DASH diet (Table 9-9) 3. Daily exercise 4. Limit sodium 5. Limit alcohol BEST PRACTICES: TEACHING STRATEGIES, DEMONSTRATIONS, ACTIVITIES, ASSIGNMENTS, AND MORE 1. Assign students the Rate Your Plate activity, “Rate Your Beverage Choices.” Use this as a springboard to discuss ways to obtain recommended amounts of water without excess calories. 2. Have students visit a local pharmacy to investigate the mineral content of supplements. The following could be assigned: A. Select 10 multiple vitamin/mineral supplements. Be sure to include at least two generic brands. List the brand name, contents, measure, and percentage of the Daily Value. For example, One A Day: Vitamin C, 60 mg, 100% of Daily Value. Have students compile the information and make into a handout for the class. Discuss which brands would be wise choices if one were looking for a vitamin/mineral supplement. Are any products available in which all minerals provide less than 150% of the Daily Value? B. Compare available calcium supplements for source of calcium, absorbability, and cost. Include various antacids in the comparison. Once again, the information could be complied and offered as a handout. Rank the calcium supplements from best choice to worst choice. Do these products contain any other nutrients? 3. Sodium is a mineral that can be highly variable in dietary intakes. It is important to help students identify high sodium food sources. This can be done several ways: A. Form small teams and have each investigate the sodium content of a specific group of food products. Have each team report to the class average sodium content and range of sodium contained in the group. B. Visit a local supermarket and identify the availability of products labeled as "low sodium," "reduced sodium," and "no added salt." How much difference is there between sodium content and cost of these products compared to the "regular" product? C. To help students understand the effect of food processing on sodium content, have them use their food composition table in the text to compare sodium content of yogurt: plain, whole milk, no solids; yogurt: plain, lowfat, milk solids added; yogurt: plain, nonfat, milk solids added. Discuss why sodium content rises as fat decreases. A similar exercise can be done comparing sodium content of raw peaches, canned peaches in heavy syrup, and peach pie. 4. Have students complete the Rate Your Plate activity “Working for Denser Bones.” Use this as a springboard to discuss ways to increase calcium in the diet. 5. Bring a variety of calcium supplements to class, including antacids. Or, have students bring to class calcium supplements they consume. Test their digestibility/ absorbability by dropping each supplement in 6 ounces of cider vinegar. Explain that vinegar has approximately the same pH as the stomach. Stir every 5 minutes and observe which ones dissolve in 30 minutes... in 60 minutes. Use this as a springboard for discussing calcium supplements. 6. Have students visit a local pharmacy and select 10 products sold as iron supplements: five for use with infants or children, four for adults, and one prenatal vitamin. The pharmacist will have to assist the student with prenatal vitamin information. Determine the source and amount of iron in these products, as well as cost per daily dosage. 7. Have students visit a supermarket to look at the breakfast cereals to find the one highest in iron and fiber and lowest in sugar. Compare their findings. Rank cereals from most nutrient-dense to least. Use this as a springboard to discuss iron sources. 8. Have students write the name of each mineral on an index card. On the back, they will list one to three key functions of that mineral; food sources; deficiency name, if appropriate; deficiency symptoms; and toxicity symptoms. Have students study these index cards in pairs until they can recall the information about each mineral. 9. Before class, write the name of each mineral on a piece of paper, index card, or "post-it." If you use paper or an index card, remember to take stick pins or tape to class to fasten the card/paper on students' backs. Secure one card/paper/post-it on the back of each student. Have students circulate throughout the room asking other students questions about the mineral posted on their back. Only yes and no questions are permitted, for example, “Am I involved in red blood cell formation?” and “Are spinach, oysters, and liver good sources of me?”. Only two questions can be asked of any person. After asking two questions of a person, students must move to someone else. Continue the game until everyone correctly identifies the mineral they are. 10. Post lists of foods around the room. Have students determine the key mineral(s) present in each group of foods. 11. Place posters with names of vitamins and minerals around the room. Give students index cards describing symptoms of deficiencies and excesses. Have them match symptom cards with the appropriate vitamin or mineral. CHAPTER 10 NUTRITION: FITNESS AND SPORTS OVERVIEW This chapter begins by addressing the importance of physical activity. Exercise program guidelines for the general population are presented. Energy metabolism and how the macronutrients are used during different muscular activities set the stage for a discussion of good dietary principles for athletes. Issues such as carbohydrate loading; diets for building muscle; special vitamin and mineral needs; the pre, during, and post-event meals; and fluid consumption are covered. Ergogenic aids are discussed in the Nutrition for Your Health section. KEY TERMS Adenosine triphosphate (ATP) Adenosine diphosphate (ADP) Aerobic Anaerobic Carbohydrate loading Creatine Ergogenic Exercise Fat adaptation Heat cramps Heat exhaustion Heatstroke Lactic acid Moderate-intensity aerobic physical activity Muscle strengthening activity Physical fitness Phosphocreatine (PCr) Physical activity Physical fitness Progression Pyruvic acid Stress fracture Vigorous-intensity aerobic physical activity STUDENT LEARNING OUTCOMES Chapter 10 is designed to allow you to: 10.1 List five positive health-related outcomes of a physically active lifestyle. 10.2 Enumerate three key elements of a sound fitness regimen. 10.3 Describe the use of carbohydrates, fat, and protein to meet energy needs during different activities. 10.4 Differentiate between anaerobic and aerobic uses of glucose, and identify advantages and disadvantages of each. 10.5 Show how muscles and related organs adapt to an increase in physical activity. 10.6 Outline how to estimate an athlete’s calorie needs and discuss the general principles for meeting overall nutrient requirements in the training diet. 10.7 Examine the problems associated with weight loss by dehydration and outline the importance of fluids during exercise. 10.8 Understand how athletes can optimize performance by consuming foods and fluids before, during, and after exercise. 10.9 List several ergogenic aids and describe their effects, if any, on an athlete’s performance. LECTURE OUTLINE 10.1 An Introduction to Physical Fitness A. Benefits of regular physical activity (see Fig.10-1) 1. Improvement of heart function 2. Less injury 3. Better sleep habits 4. Body composition improvement 5. Stress reduction 6. Blood pressure reduction 7. Blood cholesterol reduction 8. Blood glucose regulation 9. Enhanced immune function 10. Aids in weight control B. Physical activity vs exercise 1. Physical activity: any movement of skeletal muscles that requires energy, including exercise, sports, and simple unplanned activities of daily living. 2. Exercise: physical activities that are planned, repetitive, and intended to improve physical fitness (i.e., walking, biking, swimming, team sports, and running). C. 2008 Physical Activity Guidelines for Americans recommends adults avoid inactivity. 1. Engage in 150 minutes per week of moderate-intensity, or 75 minutes per week of vigorous-intensity aerobic physical activity for substantial health benefits. 2. Additional health benefits are seen with 300 minutes of moderate-intensity activity per week or 150 minutes of vigorous-intensity activity per week. 3. Include muscle-strengthening activities 2x/week. 10.2 Achieving and Maintaining Physical Fitness A. Assess Your Current Level of Fitness B. Set a Goal 1. Choose goal that is challenging but also attainable. 2. Measurable, attainable, and realistic goals provide focus and motivation. C. Plan Your Program (see Table 10-1) 1. FITT principle: Frequency, Intensity, Time, Type of exercise 2. Aerobic exercise enhances heart and lunch function. a. Uses large muscle groups in a rhythmic fashion and aim to increase your heart rate. b. ACSM recommends 30 minutes per day moderate-intensity aerobic activities 5 days/week c. Examples: brisk walking, running, cycling, etc. d. Intensity 1) Target zone for heart rate is 55%–90% of age-predicted maximum heart rate (220 – age) (see Table 10-2) a) During initiation phase, aim for lower end of target zone, and gradually progress to higher heart rate b) Medications for heart conditions may affect heart rate 2) Rating of Perceived Exertion (see Table 10-3) a) Aim for 4, which corresponds to “somewhat strong” b) “Talk test" 3. Muscular fitness encompasses strength, endurance, and power a. Training 1) Muscular strength: maximal force a muscle can exert against a load at one time 2) Muscular endurance: ability of the muscle to perform repeated, sub-maximal contractions over time without fatigue 3) Muscular power: combines strength with speed for explosive movement b. ACSM recommends including muscle strengthening activities 2–3 times per week on nonconsecutive days c. Examples: weight-lifting, Pilates, push-ups, etc. 4. Flexibility exercises enhance balance and stability a. Poor flexibility linked to chronic pain b. Flexibility prevents injury and muscle soreness while enhancing balance and stability c. ACSM recommends flexibility 2 to 3 days per week d. Examples include stretching, pilates, and tai chi. 5. Warm-up and cool-down a. Warm-up: 5–10 minutes of low intensity exercises b. Cool down: slow down for 5–10 minutes of low-intensity activity followed by 5–10 minutes of stretching. 6. Get started a. Begin with short periods of physical activity b. Build up to 30 minutes each day c. Create new goals when others are reached 10.3 Energy Sources for Exercising Muscles (see Table 10-2) A. Overview 1. ATP: immediate source of energy for body functions 2. Energy in food is converted to ATP a. ADP + food energy + phosphate group ATP b. ATP  energy to do work + ADP + phosphate group B. Anaerobic Metabolism Supplies Energy for Short Bursts of Intense Activity 1. Stored ATP a. Resting muscle can store enough ATP to keep a muscle working for about 2 to 4 seconds b. Cells must constantly and repeatedly use and then re-form ATP using various sources of energy. 2. Phosphocreatine (PCr) is the first line of defense for resupplying ATP in muscles a. Splitting phosphocreatine into phosphate and creatine supplies energy to reform ATP from ADP b. Could maintain muscle contractions for about 10 seconds c. Main advantage—activated quickly d. Major source of energy for events lasting less than 1 minute e. Not much is stored f. Strength-training athletes use creatine supplements to increase PCr in muscles 3. Anaerobic glucose breakdown a. When limited O2 supply b. Yields only 5% of ATP c. Advantage: Fastest way to resupply ATP other than PCr breakdown d. Disadvantages 1) Provides energy for events lasting only 30 seconds to 2 minutes 2) Lactic acid accumulation and short-term fatigue C. Aerobic Metabolism Fuels Prolonged Lower-Intensity Activity 1. Carbohydrates a. Main fuel for fast paced activity b. Breakdown requires O2 c. Yields energy more slowly d. Provides energy for events lasting 2 minutes to >3 hours e. Important fuel in endurance activities f. Does not produce lactic acid g. Pyruvic acid enters mitochondria where energy is released h. Yields 95% of ATP i. Bonking: decline in mental function as blood glucose declines during endurance exercise; due to depletion of liver glycogen 2. Fat a. The main fuel for prolonged low-intensity activity (slow and steady) b. Triglycerides yield 3 fatty acids and 1 glycerol c. Fatty acids travel to muscle cells and are used for energy (aerobic) d. Progressively important as duration of activity increases (>20 minutes) and intensity decreases e. Advantages: can store a lot in a concentrated form f. More fatty acids in blood = more fat used as fuel 3. Protein a. A minor fuel source, primarily for endurance exercise b. Less prominent role in fueling muscular activity c. Contributes 5% of general energy needs d. Contributes as much as 10–15% of energy as muscular stores of carbohydrate are exhausted during endurance activities e. Mostly branched-chain amino acids f. Diet provides plenty; no need to supplement D. Can Physical Training Affect Fuel Use? 1. Increased training  increased mitochondria and blood flow (more O2)  increased aerobic capacity 2. Training improves insulin sensitivity 3. Training improves ability to store glycogen 4. Training induces elevations in muscle triglyceride content increasing muscle use of fat as fuel 5. Training increases efficiency of protein use as fuel 6. Cardiovascular and respiratory systems become more efficient at providing oxygen to cells 10.4 Tailoring Nutrient Recommendations for Athletes A. Calorie needs 1. Calorie need is dependent on body size and type of training 2. Moderate activity requires 5–8 kilocalories/minute 3. Ways to determine if getting enough energy a. Keep a food diary b. Estimate percent body fat: note difference between fat percent recommended for average person vs. athlete 1) Males: 5% to 18% 2) Females: 17% to 28% 4. Consume a mix of carbohydrates, protein, and fat 5. Adjust kilocalories to achieve stable, desirable body weight a. Athlete too fat, decrease intake 200 to 500 kilocalories per day b. Athlete too thin, increase intake 500 to 700 kilocalories per day 6. Table 10-3 presents sample daily menus based on MyPlate that provide examples of various total caloric intakes B. Carbohydrate 1. Percent of total energy intake a. About 60% of kilocalories b. Low-CHO diets are not recommended for athletes 2. Grams CHO/kilogram body weight a. Minimum of 6 grams per kilogram body weight b. Endurance athletes (> 60 minutes duration) need 7 to 10 grams per kilogram body weight (~ 600 g/day) 3. The type of carbohydrate matters: not high fat (see Table 10-4) 4. Carbohydrates needed to prevent fatigue and provide muscle and liver with adequate amount to store 5. Sports drinks may aid in carbohydrate loading 6. Moderate (rather than high) fiber intake to reduce bloating and gas C. Fat 1. Up to 35% of calories 2. Emphasize rich sources of monounsaturated fat 3. Limit saturated fat and trans fat intake D. Protein 1. 0.8 to 1.7 grams per kilogram of body weight (recall RDA is 0.8) (see Table 10-5) 2. Athletes may need more protein because a. There is also increase in calorie needs b. Need for additional amino acids to repair damaged muscle tissue c. Provide enough protein for fuel as well as maintenance of protein synthesis and other metabolic processes 3. Requirements easily met by diet; supplements not needed 4. Some experts recommend 2.0 grams per kilogram for weight training a. Not well-supported by research b. Excess amino acids used for fuel c. Increased urinary calcium losses d. Increased urine production; may lead to dehydration e. Lack of CHO may lead to fatigue E. Vitamin and Minerals 1. Overview a. Athletes tend to get all vitamins and minerals needed because of higher-than-normal energy intake b. Concern if intake less than 1,200 kilocalories or vegetarian 1) May especially be low in B vitamins 2) Consume low-fat, nutrient-dense foods 3) Eat fortified foods and/or multi-vitamin 2. B vitamins support energy metabolism and red blood cell health. a. B vitamins important in energy metabolism, metabolism of amino acids, and formation of red blood cells b. Deficiency now common c. Deficiency can impair athletic performance d. At risk populations: seniors, vegans, female athletes of childbearing age, and anyone who restricts dietary intake to control weight e. Fortified foods or multivitamin can be helpful if at risk 3. Antioxidant nutrients may prevent oxidative damage. a. Exercise increases production of free radicals which can lead to fatigue and cell damage b. Athletes may need increased vitamin C and vitamin E c. Increase intake from foods such as fruits, vegetables, whole grains, and vegetable oils. 4. Iron deficiency impairs performance a. Iron needed for red blood cell formation, oxygen transport, and energy production b. Vulnerable populations 1) Female: menstrual losses 2) Vegetarians and low-calorie dieters: low intake 3) Distance runners: GI bleeding c. Sports anemia: increased blood volume dilutes iron, not true anemia d. Anemia: depressed hemoglobin level e. Check iron status at beginning and mid training season f. Supplements only on doctor's advice g. Increase intake from diet with food sources of heme iron and paired nonheme sources with vitamin C. 5. Calcium intake is important, especially in women a. Women at risk due to restriction of kilocalories by avoiding dairy products b. Women who stop menstruating need to be concerned (female athlete triad) 1) Leads to increased risk of decreased bone mass and stress fractures 2) Remedy: decrease training and gain weight 3) Bone loss may be irreversible F. Fluid 1. Fluid needs for average adults a. 9 cups/d for women b. 11 cups/d for men 2. Fluids needed to allow body to keep cool a. Sweating rates during exercise: 3 to 8 cups per hour b. Water loss >3% of body weight is associated with increased body temperature and decreased performance 3. Do not depend on thirst mechanism a. Athletes should weigh pre- and post-exercise to determine weight loss b. Monitoring color of urine is another method of assessing hydration status (no darker than lemonade) c. Drink beverages freely up to 24 hours before event d. Drink 1½–2½ cups of fluid at least 4 hours before exercise e. Consume 1.5 to 3.5 cups of fluid per hour for events lasting longer than 30 minutes f. Consume 2 to 3 cups of fluid within 4–6 hours after exercise. g. Restore weight before next exercise period h. Avoid caffeine and alcohol as they are diuretics (see Table 10-6) 4. Heat/dehydration-related illness a. Heat exhaustion 1) Depletion of blood volume 2) Symptoms a) Profuse sweating b) Headache c) Dizziness d) Nausea/vomiting e) Muscle weakness f) Visual disturbances g) Flushing of the skin 3) Treatment: move to a cool environment, sponge with water, and replace fluids b. Heat cramps 1) Occurs when fluids are replaced without also replacing sodium 2) Symptoms include painful contractions of skeletal muscles lasting up to 3 minutes at a time 3) Prevention includes moderation of activity, adequate salt intake, adequate hydration c. Heatstroke 1) Caused by high blood flow to exercising muscle, which overloads body’s cooling capacity 2) Symptoms a) Hot, dry skin b) Fainting c) Internal temperature > 104°F d) Nausea e) Confusion f) Irritability g) Poor coordination h) Seizures i) Coma 3) Circulatory collapse, nervous system damage, and death could result without treatment 4) Prevention entails closely monitoring changes in body weight due to fluid depletion 5) Treatment includes professional medical attention and keeping cool with ice packs 5. Sports drinks a. Not necessary for events < 60 minutes or weight loss 60 minutes, especially in hot weather, to maintain blood volume c. Use drinks with electrolytes and with 60 minutes because prolonged exercise depletes muscle glycogen b. “Hitting the wall:” physical and mental fatigue resulting from depletion of muscle glycogen c. Consume 30–60 g carbohydrate per hour d. Experiment during training e. Many products available (see Table 10-10) 1) Gels: 25 g/serving 2) Bars: 2–45 g/serving 3) Sport drinks: 14 g / 8 oz. f. Not enough evidence to support supplementation of branched chain amino acids as fuel during an event g. Fat during an event is unlikely to boost performance h. Tips for choosing a good energy bar 1) 40 g CHO 2) ≤ 10 g protein 3) ≤ 4 g fat 4) ≤ 5 g fiber i. Possible drawbacks of energy bars 1) Expensive 2) Overuse can lead to nutrient toxicities 4. After exercise, replenish glycogen and fluid. a. 1–1.5 grams of carbohydrate per kilogram body weight consumed within 30 minutes after endurance exercise b. Repeat every 2 hours for the next 4 to 6 hours c. Consume high-glycemic-index carbohydrates d. Combination of carbohydrate and protein foods e. Fluid and electrolyte intake essential B. Strength and Power Athletes: Strategies to Enhance Muscle Gain 1. Muscular power combines strength with speed, improving the ability to apply force quickly (ex: middle-distance running, gridiron football, rowing, swimming) 2. In general, calorie needs high with emphasis on protein intake in recovery 3. Before and during strength and power training, focus on calories, carbohydrates, and fluids. a. Ensure adequate hydration prior to an event b. Consume 4 to 7 g carbohydrate per kilogram body weight in days prior to a strength and power event c. Consume 1 to 4 g carbohydrate per kilogram body weight in pre-event meal or beverage 4. After strength and power activities, consuming carbohydrates and protein promotes recovery. a. Cells are insulin sensitive in hours after exercise b. Consume 1–1.5 g of carbohydrate per kilogram body weight to restore muscle glycogen c. Consume 20 grams high quality protein within 1–2 hours after exercise to maximize protein synthesis d. Ration of carbohydrate to protein should be 3:1 (see Table 10-11) Nutrition and Your Health: Ergogenic Aids and Athletic Performance A. Ergogenic aids to enhance athletic performance 1. Not a new practice 2. $3.6 billion spent on sports nutrition supplements in 2011 3. Ergogenic: work-producing 4. Proven ergogenic aids include a. Sufficient water and electrolytes b. Adequate carbohydrates c. Balanced and varied diet consistent with MyPyramid 5. Nutrient supplements should only be used to address specific dietary shortcomings B. Many ergogenic aids marketed to athletes are useless or dangerous 1. There is little evidence to support the effectiveness and safety of many ergogenic aids 2. FDA has only limited power to oversee supplement industry, so supplements of even proven ergogenic aids may not be of high quality C. An evaluation of popular ergogenic aids (Table 10-12) 1. Useful in some circumstances a. Creatine may improve performance in athletes who undertake repeated bursts of activity (e.g., sprinting or weightlifting) b. Sodium bicarbonate may counter lactic acid buildup, but also may induce nausea or diarrhea c. Caffeine may promote mental alertness and increase use of fatty acids by muscles d. Beta-alanine may improve performance in strength and power sports 2. Possibly useful, still under study a. Beta-hydroxy-beta-methylbutyric acid (HMB) may decrease protein catabolism, thereby increasing muscle mass b. Glutamine may enhance immune function and preserve lean body mass c. Branched-chain amino acids may serve as an energy source during endurance activities when glycogen stores are depleted 3. Dangerous or illegal substances/practices a. Anabolic steroids do increase protein synthesis, but have many dangerous side effects b. Growth hormone (used other than for medical cases of short stature) causes uncontrolled growth of the heart and other internal organs c. Blood doping may enhance aerobic performance, but also causes thickening of blood d. Gamma hydroxybutyric acid (GHB) is promoted as a steroid alternative, but causes many harmful side effects e. Ephedrine (stimulant) is promoted to improve anaerobic performance but most studies do not support this; linked to heart palpitations, anxiety, and even death BEST PRACTICES: TEACHING STRATEGIES, DEMONSTRATIONS, ACTIVITIES, ASSIGNMENTS, AND MORE 1. Assign students the Rate Your Plate activity, "Evaluating Protein Intake—A Case Study." They should complete the calculations and the interpretation and application sections. Use this as a springboard for discussing protein intake for sport. 2. Have students look at their carbohydrate intake (in grams) from their diet that they recorded in Chapter 1. Ask them to list extra foods, high in carbohydrate and low in fat, they would need to eat to increase their intake to 600 grams per day, as a triathlete might eat. Have them list the servings they would choose and the amount of carbohydrate in each serving to ultimately sum to 600 grams. 3. Ask students to record their fluid intake in ounces or cups for one day. They shouldn't include milk. Have them total the amount they consumed in one day. Use this as a springboard for discussing fluid intake for sport. 4. Have students go to grocery stores, sports shops, or nutrition centers and look at commercial sports drink prices. In class, together with students, formulate these homemade sports drinks: a. Drink 1: Use 2 tablespoons sugar, 1/10 teaspoon salt, 1/16 of a teaspoon potassium chloride, to every quart of water. Flavor it with lemon or lime juice. b. Drink 2: Mix 1/2 cup water, 1/2 cup nonfat dry milk powder, 1/4 cup glucose polymer (can purchase in stores specializing in sports merchandise), 3 cups skim milk, 1 teaspoon flavoring for palatability (cherry, vanilla, or chocolate extract) Purchase a commercial sports drink or two and allow each student to taste and compare homemade and commercial sports drinks. Discuss the cost: benefit of purchasing versus making sports drink. Use this activity as a springboard to discuss fluid intake for athletes. 5. Have students write research papers on the relationship between proposed ergogenic aids and performance. Students can work in groups or individually. Have each student or group choose one substance to research. Table 10-12 can be used as a guide. Have students present their findings to the class. 6. Ask students to calculate 2% of their body weight. They should also weigh themselves before and after a period of exercise. Have them calculate how much fluid they should have to prevent losing more than 2% of their body weight. Instructor Manual for Wardlaw's Contemporary Nutrition Anne M. Smith , Angela L. Collene 9780078021374, 9781260092189