CH-9-10 Minerals – Nutrition for Sport and Exercise : Chapter Notes

This Document Contains Chapters 9 to 10 Chapter 9: Minerals Overarching Concepts 1. Minerals differ from vitamins in several ways. 2. Extreme intakes—too little or too much—are detrimental to health. 3. Athletes in training are unlikely to need more than the DRI. 4. Adequate mineral intake is associated with adequate caloric intake and a variety of nutrient-dense foods. 5. Adequate calcium intake is critical across the life cycle to maintain calcium homeostasis, calcium balance, and bone mineral density. 6. Iron-deficiency anemia impairs endurance performance. 7. A “food first, supplements second” policy can serve athletes well. Learning Objectives LO 9.1 Classify minerals and describe their general roles. LO 9.2 Explain how mineral inadequacies and excesses can occur and why each might be detrimental to performance and health. LO 9.3 Describe the factors that increase, maintain, and decrease bone mineral density, including a discussion of the minerals associated with bone formation and their effects on performance and health. LO 9.4 Describe the role of iron in red blood cell formation and the impact of low iron intake on performance and health. LO 9.5 Describe the roles of minerals in the immune system. LO 9.6 Compare and contrast minerals based on their source—naturally occurring in food, added to foods during processing, and found in supplements—including safety and effectiveness.. Chapter Outline I. Introduction A. Pre-test assessment B. Introduction to minerals 1. Minerals differ from vitamins in many ways 2. Inorganic, not well absorbed, not easily excreted II. 9.1 Classification of minerals (see Table 9.1, page 324) • There are 21 essential minerals. • A DRI and UL have been established for most minerals. • Moderate to rigorous exercise may increase the loss of some minerals, which typically can be replaced with properly chosen foods. • In the United States, dietary intake of several minerals is less than recommended. A. Amount found in the body 1. Macrominerals a. Found in relatively large amounts b. Calcium, phosphorous, magnesium c. Sodium, potassium, chloride, sulfur 2. Microminerals (trace minerals) a. Iron, zinc, copper, selenium b. Others such as manganese and molybdenum B. Functionality (see Table 9.2, page 324) 1. Proper bone formation a. Calcium, phosphorus, magnesium, fluoride 2. Electrolytes a. Sodium, potassium, chloride 3. Enzyme-related functions a. Iron, zinc, selenium, copper C. A recommended daily intake has been established for many minerals (see Table 9.3, page 330) 1. Dietary Reference Intakes (DRI) a. How much is enough? 2. Tolerable Upper Intake Level (UL) b. How much is too much? 3. Internet café: Reliable information about minerals on the Web D. Moderate to rigorous exercise increases the loss of some minerals 1. Mineral loss in sweat and urine may be greater in athletes 2. Adaptation to conserve some minerals as athletes acclimate to heat 3. Small to moderate losses can be offset by dietary intake 4. Larger losses may need supplementation 5. Zinc moves from muscle cells into the ECF and might be excreted in urine E. Poor food choices by athletes and sedentary people often lead to low mineral intake 1. Athletes likely low in dietary calcium, iron, zinc, selenium, magnesium, copper 2. Energy-restricted athletes at the most risk 3. Nutrient-dense foods are important to meet overall needs 4. The best approach for determining mineral intake is personalized dietary assessment for each athlete Question for discussion: Why do many athletes and nonathletes fail to consume an adequate amount of minerals? III. 9.2 Mineral deficiencies and toxicities • An adequate amount of each mineral is needed for proper biological function, but an excessive amount can be detrimental. • Moderate to rigorous exercise increases the loss of some minerals, but with a few exceptions (for example, sodium) the losses are small and easily replenished with food. • Most athletes can obtain sufficient amounts of minerals from food if the diet is well balanced. • Low calcium and iron intakes, which are more prevalent in females, may result in subclinical and clinical deficiencies. Supplementation is appropriate for some individuals. • Mineral toxicities are rare but possible. A. Mineral homeostasis 1. Generally maintained by adjusting absorption and excretion a. If storage is high, absorption decreases b. If storage is low, absorption increases 2. Hormonal and other mechanisms are also influential B. Many factors influence mineral absorption (see Table 9.5, page 332) 1. Factors that increase mineral absorption a. Presence of a growth state b. Presence of a deficiency state c. Larger (vs. smaller) amounts consumed in food d. Presence of food in the GI tract e. Certain compounds in food (e.g., vitamin C, soluble fiber, MFP factor) f. Certain chemical forms 2. Factors that decrease mineral absorption a. Increasing age b. Poor health or GI disease c. Presence of competing minerals d. Certain compounds found in food (e.g., phytic acid, insoluble fiber) e. Excessive supplementation of individual minerals f. Presence of food in the GI tract g. pH of the GI tract h. GI transit time 3. Consume a variety of nutrient-dense foods a. Provides a wide array of minerals b. Minimizes risk for competition for absorption c. Maximizes chances for adequate absorption C. It is important to guard against mineral deficiencies 1. General characteristics a. Deficiencies develop over time b. No signs or symptoms initially c. Signs or symptoms are non-specific when they first occur d. Specific symptoms associated with severe deficiencies 2. Prevalence of subclinical mineral deficiencies a. Iron deficiency without anemia 1) In U.S., 2-5% of males, 9-16% of adolescent females, 12% of nonpregnant adult females 2) Prevalence may be higher in female endurance athletes and vegetarians 3) Effect on performance not known but it is prudent to avoid this condition b. Osteopenia 1) Low bone mineral density 2) In U.S., 22 million women and 12 million men 3) May be as high as 11-22% of athletes c. It is reasonable to assume some athletes could have subclinical deficiencies of iron, calcium, zinc, selenium, and magnesium d. Subclinical deficiencies of other minerals not well documented 3. Prevalence of clinical mineral deficiencies a. Iron-deficiency anemia 1) In U.S., 3% of females 2) Prevalence in female athletes estimated to be 3% or more 3) Prevalence in male athletes very low but not zero 4) Results in fatigue and impaired performance b. Osteoporosis 1) In U.S., 8 million women and 2 million men 2) Bone loss exacerbated with low estrogen (associated with inadequate dietary intake, low caloric intake, and low body fat) 3) 10-13% female distance runners 4) Small % of amenorrheic female distance runners < age 30 c. Clinical deficiencies negatively affect performance and health D. Mineral toxicities are rare but possible 1. Little is known about toxicity in well-nourished individuals 2. Tolerable Upper Intake Level (UL) 3. Some supplements are highly absorbable 4. Supplement carefully and monitor dosage Question for discussion: Why is it recommended that people check with their doctor before taking a mineral supplement? IV. 9.3 The roles of minerals in bone formation • Adequate nutrient intake, in particular calcium, vitamin D, and protein, and weight-bearing exercise are necessary throughout life for bone health. • The key to preventing osteoporosis is achieving peak bone mineral density. • Calcium intake is particularly low by teenage females, raising serious concerns about future bone health. • Calcium supplementation in mid- and later life has some benefit, but cannot completely offset the calcium loss from bone that accompanies aging. • Athletic amenorrhea is detrimental to bone health. A. Bone-forming minerals 1. 90% is calcium and phosphorus, used to form hydroxyapatite 2. Small amount of fluoride 3. Several minerals have indirect roles 4. Vitamin D is critical to bone development B. Bones have both structural and metabolic functions 1. Bone growth, modeling, and remodeling a. Increased length and thickness during childhood and adolescence b. Growth is longitudinal (length) and radial (thickness) c. Modeling is the process in which bones are formed and shaped d. Mechanical stress strengthens bones e. Increased mineral content until approximately age 35 f. Slow mineral loss after approximately age 35 g. Accelerated mineral loss in females when estrogen production declines 2. Bone remodeling a. Bone turnover is constant b. Site of bone remodeling 1) Cortical bone a) approximately 80% of skeleton b) Shafts of the long bones and on the surface 2) Trabecular bone a) approximately 20% of skeleton b) Ends of the long bones and under the surface c) Honeycomb-like structure d) Greater surface volume, metabolic activity, and turnover c. Rate and time of bone remodeling 1) Rate a) 1-2% of entire skeleton but approximately 20% of trabecular bone b) approximately 1 million active sites each day 2) Length of time a) In children, weeks b) In young adults, approximately 3 months c) In older adults, approximately 6 to 18 months d) Over a ten-year timeframe an adult’s skeleton will be completely remodeled d. Osteoclasts resorb bone 1) Stimulated by physical activity and microfractures 2) Stimulated by hormones—PTH and calcitriol e. Osteoclast/osteoblast balance 1) In children and adolescents, deposition is favored 2) In young adults, balance generally exists 3) In middle-aged to older adults, resorption is favored (more osteoclastic activity) C. Achieving peak bone mineral density is critical to long-term health 1. Highest lifetime bone mineral density a. Trabecular bone by approximately age 30 b. Cortical bone by approximately age 35 2. Approximately 60% is genetically determined 3. Important influences (see Figure 9.3, page 339) a. Adequate calcium, vitamin D, and protein intakes b. Weight-bearing exercise or activity or high-impact exercise (jumping, strength training) c. Hormones 4. Nutritional factors affecting peak bone density a. Calcium 1) Greatest amount needed for ages 9 to 18 (1,300 mg/day) 2) Substantial need throughout adulthood (1,000 to 1,200 mg/day) a) Average adult female intake is approximately 650 mg/day b) Average adult male intake is approximately 925 mg/day b. Vitamin D 1) 5 mcg/day until age 50 2) Need increases with age a) 10 mcg ages 51 to 69; 15 mcg age 70 and above b) Conversion to active form declines c) Exposure to UV light declines c. Protein 1) Adequate protein in children is associated with bone growth 2) Necessary for secretion of IGF-1 5. Mechanical factors affecting peak bone density a. Weight-bearing exercise b. High-impact activities c. Excess body weight D. Bone loss associated with aging 1. In women, 0.25 to 1.0% yearly until age 50 2. With estrogen deficiency, 1-2% yearly (mainly from vertebrae) 3. In the decade after menopause, 20-30% of bone density from trabecular bone and 5-10% from cortical bone 4. In older men, approximately 1% yearly 5. Bone loss associated with low calcium availability for functional use and to maintain calcium homeostasis 6. Under hormonal regulation 7. Normal calcium excretion is approximately300 mg between GI secretions and urine losses E. Calcium may be taken from bone to maintain calcium homeostasis (see Figure 9.5, page 342 Calcium regulation) 1. Hormonally controlled a. Parathyroid hormone (PTH) b. Calcitriol (form of vitamin D) 2. Calcium homeostasis a. Regulation of calcium in the blood and extracellular fluid b. Primarily controlled by PTH c. Critical for proper nerve and muscle function d. Fast calcium exchange 1) PTH activates calcium pumps in membranes surrounding bone fluid 2) Calcium is mobilized from bone fluid not mineralized bone 3) PTH stimulates calcium resorption in kidney and increased GI absorption 3. Calcium balance a. Total absorption, distribution, and excretion b. Different from calcium homeostasis but related c. Increased or decreased absorption and excretion as needed d. Bone turnover is balanced under normal conditions 4. Long-term low calcium intake a. Bone turnover is not balanced b. Slow calcium exchange 1) PTH stimulates dissolution of bone 2) Increases osteoclastic activity; decreases osteoblastic activity 3) Calcium (and phosphate) released from bone 4) Over time, integrity of bone is decreased F. Bone loss is associated with lack of estrogen 1. Powerful influence on osteoclast number and activity 2. Generally associated with menopause 3. Also present in some young female athletes 4. Distance runners, ballerinas, and gymnasts are at greater risk 5. Focus on research: Does the Disruption of the Menstrual Cycle That Occurs in Some Athletes Have Health Implications? G. The roles of calcium and exercise in preventing or reducing bone loss associated with aging have not been fully established 1. Diet-related a. In women after age 70, calcium supplementation is beneficial b. Calcium supplementation after age 35 may be prudent to slow calcium losses from bones c. Calcium supplementation in this group will not offset all of the factors that affect a decline in BMD d. In women under 50 and most men, adequate calcium and vitamin D intakes slow the loss of bone calcium e. In the first 10 years after menopause, calcium supplementation has a small, positive effect 2. Exercise-related a. High-intensity weight-bearing activities b. Resistance training c. Mechanical stress increases bone density d. Other types of exercise are beneficial but do not slow bone loss H. Recommended dietary intakes of calcium and vitamin D have been revised 1. 2010 DRI established new RDAs and ULs (see Table 9.8, page 345) I. Many people consume an inadequate amount of calcium daily (see Table 9.9, page 346) J. There are numerous strategies for increasing dietary calcium consumption 1. Calcium sources a. Milk and milk products b. Reduced-lactose or lactase-treated milk products c. Fermented milk products d. Calcium-containing vegetables such as cabbage, broccoli, and green leafy vegetables e. Calcium-fortified foods (Table 9.10, page 348 Nondairy Sources of Calcium) f. Calcium supplements 2. Many people consume an inadequate amount of calcium daily 3. Over-consumption of calcium supplements (UL 2500 mg/day) can lead to kidney stones and displacement of other nutrients K. Phosphorus, fluoride, and magnesium are also involved with bone health 1. Phosphorus is abundant in food 2. Fluoride is added to supplements or water 3. Magnesium is found in vegetables, nuts, beans, and legumes Question for discussion: In what ways does society promote poor calcium intake and a sedentary lifestyle? V. 9.4 The roles of minerals in blood formation • Iron is necessary for proper red blood cell formation. • Low iron intake may result in iron deficiency or iron-deficiency anemia. • Iron-deficiency anemia negatively affects performance. • Premenopausal female athletes have the highest risk of developing iron deficiency and iron-deficiency anemia, particularly if caloric intake is restricted and the diet lacks iron-rich foods. • Iron supplementation may be beneficial for some female athletes, but it should not be self-prescribed. A. Iron is an integral part of hemoglobin 1. Hemoglobin (Figure 9.11, page 349 Simplified hemoglobin and heme molecules) a. Iron-containing protein b. Necessary for oxygen, carbon dioxide, and nitric oxide transport c. Normal: 12.1 to 15.1 g/dl in females; 13.8 to 17.2 g/dl in males 2. Hematocrit a. Measure of oxygen-carrying capacity b. Expressed as % of total blood plasma volume c. Normal: approximately 42% in females; approximately 45% in males 3. Iron deficiency anemia a. Most common nutrition-related anemia b. Low iron stores may be due to: 1) Poor intake 2) Poor absorption 3) Excessive blood loss c. Table 9.11, page 350 Nutritional and Non-Nutritional Anemias B. Blood tests can help detect iron deficiency (see Table 9.12, page 351) 1. Common measures are hemoglobin, hematocrit, and ferritin 2. Iron status declines over time a. As iron stores are being depleted, hemoglobin and hematocrit do not decline initially b. Serum ferritin concentration declines 3. False (runner’s) anemia C. Iron-deficiency anemia negatively affects performance 1. Iron-deficiency anemia impairs performance a. VO2max (aerobic capacity) declines b. Endurance capacity declines c. A decrease in iron-containing compounds decreases oxygen utilization 2. Effect of iron deficiency without anemia on performance is unclear D. The prevalence of iron deficiency and iron-deficiency anemia in female athletes is likely higher than in the general population 1. Unlikely in most males (<2% in males under 70 years old) 2. Infrequently seen in adolescent males or male endurance athletes (5%) 3. 12% of females 20-49 years old (CDC), approximately25% of female endurance athletes in cited studies 4. Some medications induce bleeding and loss of iron 5. Greatest risk is for menstruating females 6. Athletes with low caloric intake are at greater risk 7. Sweat loss 8. Iron loss in feces and urine in times of intensive training E. Athletes should consume a variety of iron-containing foods 1. Adequate energy intake 2. Variety of iron-dense foods (Table 9.14, page 355 Iron-Containing Foods) 3. Heme (animal) sources are better absorbed than nonheme (plant) sources 4. Vitamin C increases iron absorption Question for discussion: Why might a female distance athlete need a blood test every 6 months? VI. 9.5 The roles of minerals in the immune system • Rigorous training and prolonged exercise suppress the immune system. • Inadequate intake of zinc, magnesium, or selenium impairs the immune system, as does excessive intake of zinc or iron. A. The immune system protects the body from disease 1. Immunity a. Non-specific immunity (skin, respiratory system, and GI tract) b. Specific antibodies c. Cytokines regulate the immune system 2. Zinc a. Widely found in cellular enzymes b. Involved in various immune functions c. DRI is 8 mg/day for females; 11 mg/day for males d. Most endurance athletes (approximately90%) do not meet the DRI e. Overtraining and zinc deficiency can result in repeated URTI f. Supplementation (low dose) is appropriate when DRI isn’t met through the diet g. Supplemental zinc can interfere with iron and copper absorption and decrease lymphocyte response 3. Selenium a. Involved in cellular and immune system function b. Found in meat, fish, poultry, whole grains, and nuts c. Depressed immunity is associated with deficiency 4. Iron a. Plays important role in immune system functions b. Excess iron impairs immune function Question for discussion: How can athletes determine if their intake of minerals is above inadequate but below excessive? VII. The adequate intake of all minerals • Consumption of a variety of nutrient-dense foods and sufficient caloric intake are associated with an adequate intake of minerals. • Supplementation, particularly iron and calcium, may be beneficial to provide minerals missing from the diet. • Iron supplements should not be self-prescribed. A. The key to obtaining all the minerals needed from food is to consume a nutrient-dense, whole-foods diet 1. A varied, nutrient-dense diet can provide adequate amounts of minerals 2. High-sugar/high-fat diets often do not meet daily mineral requirements 3. Consume an adequate amount of calcium and iron from food B. The dose and potency of a mineral supplement can vary substantially from brand to brand 1. Mineral-fortified foods a. Some foods have many minerals added b. Degree of absorption is unknown 2. Multimineral supplements a. Dosages may exceed the DRI or UL for some nutrients b. Degree of absorption is not known 3. Supplementing with individual minerals a. Calcium and iron are most common b. Should be physician prescribed, not self-prescribed c. Likely to affect absorption of other minerals d. High bioavailability may not be desirable 4. Spotlight on supplements: How Beneficial is Chromium Supplementation for Athletes? a. Some may contain highly absorbable form b. Enhances insulin sensitivity c. DRI for adults 20-35 mcg (depends on gender and age) d. Doses < 200 mcg seem safe e. Effectiveness for increasing muscle mass and decreasing body fat unclear Question for discussion: When it comes to minerals, what is the danger for athletes who think that “more” is always “better”? IX. Summary and review A. Chapter summary B. Post-test assessment C. Review questions D. References Supplementary Teaching Materials and Classroom Activities Note: The text chapter includes an application exercise involving the selection and evaluation of a mineral supplement for a high school gymnast (p. 360). Activity 9-1 Have students bring in an empty bottle for a mineral supplement that they are consuming now or have consumed in the past. For those students who do not buy mineral supplements, have them bring in a label from a highly fortified food that they eat. Many students consume energy bars or fortified cereal, so it is not difficult for each student to find one product label. Students can then compare the amount of minerals they consume from fortified foods and mineral supplements to the DRI and the UL. They can also compare the amount in the fortified foods and supplements to naturally occurring sources of minerals. Activity 9-2 Continue to have students evaluate their own 24-hour dietary intake over a period of 1 to 3 days (see Chapter 4, Activity 4-3), this time for minerals. There are numerous in-class activities available if students have completed the dietary analysis and bring it to class. Some suggested activities include having students: 1. Gather data about the average mineral intake of students in the class. Using a show of hands of those students who wish to participate, determine the number and/or percentage of students who met the DRI for four minerals analyzed (calcium, iron, magnesium, zinc). Sub-divide the group into those that consumed sufficient kilocalories daily and those that did not. Have students draw conclusions about the relationship between caloric and mineral intakes. 2. Estimate intake of minerals from naturally occurring food sources only. Compare to the DRI. Estimate intake of minerals from naturally occurring and fortified foods. Compare to the DRI. 3. Compare mineral intake from all sources to the Tolerable Upper Intake Level (UL). 4. Identify foods consumed that were excellent sources of a particular mineral. 5. Identify foods that are nutrient dense. 6. Evaluate both vitamin and mineral intakes. How many students met the DRI for all the vitamins and minerals from naturally occurring food sources only? From naturally occurring and fortified food sources? From all sources including supplements? Is it possible to obtain all the vitamins and minerals from food sources? 7. Discuss strategies for changing mineral intake. List strategies that students have used successfully in the past as well as barriers they have encountered. Thorough evaluation of the dietary analysis to determine if mineral needs were met or well matched to the training cycle requires more time and is generally completed outside of class. Activity 9-3 Have students evaluate websites associated with mineral supplements targeted to athletes. This can be an in-class demonstration with websites pre-selected by the instructor or an out-of-class assignment. Student Assignment The purpose of the assignment is to evaluate the content material of a website selling mineral supplements to athletes and active people. Using a search engine, enter the words “mineral supplements + athletes” into the search box. Choose one commercial site (.com) and answer the following questions about the website. 1. What is the URL of the website? 2. Describe the product being sold. Who is the target audience? How is the product supposed to work? 3. Describe the objective information found on the site (e.g., ingredients, dose, physiological or biochemical roles, scientific evidence). 4. Describe the subjective information (e.g., advertising, testimonials). 5. Evaluate the objective information (e.g., comparing factual information on the site to information found in the textbook). 6. Describe the subjective information that you think would influence someone to purchase mineral supplements from this website. In your opinion, what is most influential? 7. What information would you like to have seen on the website? 8. Was the following statement clearly visible on the website: “This product is not intended to diagnose, treat, cure or prevent any disease. These statements have not been evaluated by the Food and Drug Administration.” 9. Is the product being sold legal, ethical, safe, and effective? If not, why not? 10. Write a one-paragraph summary of this website. Crossword Puzzle Answer Key 1. osteoclast 2. osteoblast 3. excretion 4. hydroxyapatite 5. chondrocyte 6. hematocrit 7. ferritin 8. hormone 9. osteoporosis 10. calcitriol 11. resorb 12. serum 13. parathyroid Word Find Puzzle Answer Key • 4 minerals critical for bone formation: calcium, phosphorus, magnesium, fluoride • 3 major electrolytes: sodium, potassium, chloride • 3 trace elements that may be lost in sweat or urine: zinc, iron, copper • 4 food components that inhibit mineral absorption: phytic acid, oxalates, insoluble fiber, fat • 2 types of cells involved in skeletal growth: osteoblasts, osteoclasts • 2 hormones that regulate calcium balance: parathyroid hormone, calcitriol • 3 serum values used to evaluate iron status: hemoglobin, hematocrit, ferritin • 3 rich food sources of copper: seafood, nuts, seeds Chapter 9 Crossword Puzzle Across Down 4. The principal storage form of calcium and phosphorus in the bone. 6. The percentage of the volume of blood that is composed of red blood cells. 9. Disease of the skeletal system characterized by low bone mineral density and deterioration of the bone’s microarchitecture. 10. 1,25-dihydroxyvitamin D3, a hormonally active form of vitamin D. 11. To break down and assimilate something that was previously formed. 13. The _____ glands produce a hormone that helps to raise blood calcium by stimulating bone calcium resorption. 1. Bone-removing cell. 2. Bone-forming cell. 3. The process of eliminating compounds from the body. 5. A cartilage cell. 7. Iron-containing storage protein. 8. A chemical compound that has a regulatory or stimulatory effect. 12. The fluid that separates from clotted blood; similar to plasma but without the clotting agents. Chapter 9 Word Find Puzzle P O T A S S I U M E H T I S M L D N D N E U E D I R O L H C Y S T A C N I Z Y U M O S T E O C L A S T S G D I B I O V T U A N O B H O I O G B N I R O N P E M S D F L U O R I D E U E N A L T H C O P P E R A N F N U O T S T M G I O R E C H G Y P D S G M N Y I K O O N S L R A Y F O I R O U T N O U N N M H P A R A T H Y R O I D H O R M O N E E H A Y N I A U E C M T H A U P M D H M O S S S C S G L Y E H I L W U O I U A R T D E A T A C T F E R R I T I N H T U I E E C C R E E T A N D O Z W F E O S F E I I S A O S T E O B L A S T S C U A S T D O O F A E S K A U J A Y L R R T O F I R E B I F E L B U L O S N I O X A L A T E S L O I R T I C L A C T Instructions: In the grid above, find the following words or phrases, and then write them beside each clue. • 4 minerals critical for bone formation: • 3 major electrolytes: • 3 trace elements that may be lost in sweat or urine: • 4 food components that inhibit mineral absorption: • 2 types of cells involved in skeletal growth: • 2 hormones that regulate calcium balance: • 3 serum values used to evaluate iron status: • 3 rich food sources of copper: Chapter 10: Diet Planning: Food First, Supplements Second Overarching Concepts 1. Athletes need a comprehensive nutrition plan to match the demands of training and competition. 2. The keys to a nutritious diet are appropriate energy intake and the consumption of a variety of nutrient dense foods. 3. Diet planning must be highly individualized. 4. Athletes must develop specific strategies for appropriate food and fluid intake before, during, and after exercise. 5. For those who choose to consume caffeine or alcohol, moderation is recommended. 6. Dietary supplements should be judged on the basis of ethics, legality, safety, and effectiveness. 7. Most herbals and botanicals are more similar to drugs than to foods. 8. Food and supplements are not mutually exclusive, rather, they are complementary. Learning Objectives LO 10.1 Explain how energy intake and nutrient density are fundamental to diet planning. LO 10.2 Create a 1-day diet plan for an athlete based on MyPlate guidelines, and make practical suggestions for food and fluid intake prior to, during, and after exercise. LO 10.3 Discuss the risks and benefits of caffeine and alcohol use by athletes. LO 10.4 Discuss the role of supplementation in an athlete’s diet, and summarize the safety and effectiveness of popular supplements. LO 10.5 Explain how a comprehensive nutrition program supports training, recovery, performance, and good health. Chapter Outline I. Introduction A. Pre-test assessment B. Introductory concepts 1. Diet is a pattern of eating 2. Nutrition periodization is a diet plan that matches the needs of training 3. Both energy (kcal) and nutrient intakes are important II. 10.1 Energy: The basis of the diet-planning framework • An estimate of daily caloric intake forms the basis for planning the athlete’s diet. • Caloric intake can change substantially based on volume of training. • Daily energy intake for athletes typically ranges from 30 to 60 kcal/kg. • Within caloric needs, carbohydrate, protein, and fat intake must be balanced to support training and performance. • Choosing nutrient-dense foods helps athletes meet their nutrient needs within their caloric needs. A. Estimating energy needs (Table 10.1, page 369) B. General principles 1. Humans are designed to be biologically active a. Active individuals need more kcal b. Higher-caloric diets make it easier to obtain needed nutrients (nutrient density is critical) c. Caloric need for athletes can range considerably by individual and phase of training d. Genetic influence 2. Energy needs will vary with training cycle a. Usually lowest in the “off-season” b. High-volume training periods can substantially increase need (e.g., Figure 10.1 Training schedule and estimated energy expenditure of a female collegiate rower) c. Daily intake of < 30 kcal/kg is not typically recommended d. Range = 30-60 kcal/kg per day C. A dietary prescription helps athletes consume the proper amount of carbohydrates, proteins, and fats within their energy needs 1. Determining CHO, protein, fat, and alcohol intakes a. Sufficient CHO 1) Based on adequate resynthesis of muscle glycogen daily 2) Calculate kcal provided by CHO b. Sufficient protein 1) Calculate kcal provided by protein c. Sufficient fat 1) ≈1.0 g/kg body weight (assumes energy balance) d. “Discretionary calories” 1) Alcohol 2) Foods with a low nutrient density 2. Modifications to reduce body fat a. “Discretionary calories” reduced or eliminated b. Mild to moderate reduction in dietary fat c. Increased energy expenditure d. Goal is usually a 500 kcal/day deficit e. Larger deficits make it difficult to train and recover glycogen stores f. Individualized diet plan needed 3. Underweight athletes a. Can be genetic b. Goal is usually a 500 kcal/day increase c. Difficult for underweight athletes to increase weight d. Calorie-dense foods e. Individualized diet plan needed D. Consuming nutrient-dense foods is the key to eating nutritiously without consuming excess calories 1. Relatively high concentrations of nutrients compared to kcal a. Low-fat dairy products b. Most fruits and vegetables c. Whole grains, beans, legumes d. Lower-fat meat, fish, poultry e. Not necessarily low in kcal (e.g., nuts) 2. Low-nutrient-dense foods a. Sugar b. Alcohol c. When sugar and fat are added, nutrient density typically declines d. Discretionary calories Question for discussion: What are the problems associated with a lack of diet planning, particularly caloric intake? III. 10.2 Translating nutrient recommendations into food choices • Athletes need a comprehensive, individualized nutrition plan to support training, meet body composition goals, optimize performance, and maintain good health. • Food intake needs to be distributed across the day with special consideration for intake before, during, and after exercise. • Trial and error is needed to find strategies that work for the individual athlete. • Caffeine is safe in moderate amounts for adults and may enhance performance due to central nervous system stimulation. • Alcohol has a negative effect on performance, but has beneficial health effects when moderate amounts are consumed. A. Guidelines for meal planning 1. Food Intake Patterns (MyPlate) 2. Especially useful for those with little knowledge of nutrition 3. Public domain information B. Each athlete should have an individualized diet plan 1. The key to diet planning 2. May involve a new dietary pattern 3. May involve modification of current diet C. Food intake needs to be distributed appropriately throughout the day 1. Food and fluid intake prior to exercise a. Goals 1) Provide glucose 2) Delay fatigue during prolonged exercise 3) Prevent hypohydration and excessive dehydration 4) Minimize gastrointestinal distress 5) Satisfy hunger b. Guidelines 1) All guidelines are subject to trial and error 2) Timing a) Work backwards from time of exercise onset (if known) b) Adjust volume of food and fluid based on time c) CHO (1) 1.0 g/kg body weight 1 hr prior, 2.0 g/kg 2 hrs prior, etc. (2) Depends on gut tolerance d) Protein and fat (1) Some protein is usually included (2) Fats provide satiety but must allow for slow absorption e) Adjust pre-training guidelines for pre-competition intake (Figure 10.8 Guidelines for Food and Fluid Intake Prior to Exercise) f) The wrong pre-competition meal is more detrimental than the right pre-competition meal is beneficial! 2. Food and fluid intake during exercise a. Goals 1) Provide glucose 2) Delay fatigue 3) Prevent hypohydration and excessive dehydration 4) Prevent overconsumption of water 5) Prevent excessive changes in electrolyte balance 6) Replace sodium, if losses are large or rapid 7) Minimize gastrointestinal distress b. CHO 1) Limited CHO stores 2) As endurance exercise continues, higher % derived from blood glucose 3) Liver glycogen tries to compensate but capacity is limited 4) CHO intake allows blood glucose concentration to remain within the normal range 5) Studies show CHO intake of ≈30 to 60 g/hr can delay fatigue 6) Intake beneficial for endurance, ultraendurance, and “stop-and-go” athletes c. Fluids and electrolytes 1) Customized fluid and electrolyte intake plan 2) Avoid over- or under-consumption of fluid 3) Excessive sodium losses should be replaced during exercise a. ≈1 g/hour 4) Endurance athletes often include CHO in the fluid a. ≈4 to 8% CHO 3. Food and fluid intake after exercise (see Figure 10.21, page 382) a. Goals 1) Provide CHO to resynthesize muscle and liver glycogen 2) Provide proteins to aid in the repair of muscle 3) Rehydrate and reestablish euhydration 4) Replace lost electrolytes 5) Avoid GI upset b. Timing is critical 1) Begin recovery strategies as soon after exercise as practical 2) Cell sensitivity and permeability are high 3) CHO a) Muscle glycogen synthesized at highest rate immediately after exercise b) Two-hour delay results in substantial reduction of muscle glycogen resynthesis c) ≈1.5 g/kg body weight in first hour post-exercise d) Medium- to high-glycemic index foods are beneficial e) ≈0.75 to 1.5 g/kg each hour over the next three hours 4. Protein a) Intake immediately after exercise is beneficial b) 10-20 g high-quality protein as soon as possible, but not more than 2-3 hours after exercise c) Be practical (e.g., chocolate milk, turkey sandwich) 5. Fluid and electrolytes a) Intake immediately after exercise is important b) ≈ 1.5 L (1,500 ml) fluid per kg of body weight lost c) Consume enough fluid to be euhydrated before next exercise session d) Consume foods containing sodium e) Consume a variety of foods that contain other electrolytes (fruits and vegetables) Question for discussion: The team bus stops at a cluster of fast food restaurants for dinner. What would be the best menu choices for a postexercise meal? IV. 10.3 The risks and benefits of caffeine and alcohol consumption • Caffeine is safe in moderate amounts for adults and may enhance performance due to central nervous system stimulation. • Alcohol has a negative effect on performance, but may have beneficial health effects when moderate amounts are consumed A. Many athletes consume caffeine safely and effectively as a central nervous system stimulant 1. General characteristics a. Legally and socially acceptable stimulatory drug b. Psychotropic drug c. Primary ingredient is methylxanthine d. Considered safe at low doses, but does have side effects e. May be a banned substance at certain urinary concentrations f. Used for performance enhancement, weight loss, and CNS stimulation 2. Caffeine content of food and beverages (Table 10.4) a. Caffeinated coffee, tea, soft drinks, energy drinks, some medications b. Amount added to food does not have to appear on the label 3. Safety of caffeine a. Generally considered safe but addictive b. Side effects 1) Increased blood pressure at rest and during exercise 2) Increased heart rate 3) Gastrointestinal distress 4) Insomnia 5) Addiction cited at doses as low as 100 mg/day c. Moderate doses of 500 mg may result in irritability, anxiety, headaches, etc. 2) Moderate doses (up to ≈450 mg) in athletes do not negatively affect hydration status 3) Use by hypohydrated athletes is a concern 4. Effectiveness of caffeine as a performance enhancer a. Fatty acid mobilization increased but does not spare muscle glycogen b. Effective as a central nervous system stimulant c. Masks fatigue d. Increased pain threshold e. Trial and error, as sensitivity varies f. Energy drinks might overstimulate and prevent the desired effect 5. Effectiveness of caffeine for weight loss a. By itself, does not result in fat or weight loss b. Enhances the effect of ephedrine 6. Caffeine as a banned substance a. May be banned by some governing bodies b. Exceeding the threshold would probably impair performance B. Athletes should consider the risks and benefits of alcohol consumption 1. General characteristics a. Ethanol consumption described as “drinking” b. One drink is defined as: 1) ½ oz ethanol 2) About 3 to 4 oz wine 3) 10 oz wine cooler 4) 12 oz beer 5) 1 ½ oz hard liquor c. Moderate consumption is defined as: 1) Up to 1 drink/day for women and up to 2 drinks/day for men d. Contains 7 kcal/g 2. Alcohol use by athletes a. Though not a banned substance, most universities have team rules that ban or limit alcohol use b. More males than females binge drink c. May be used as a coping mechanism for anxiety and depression d. Alcohol intake causes and extends depression 3. Effect of alcohol on training or performance a. Large individual variations b. When alcohol replaces CHO in muscle, glycogen resynthesis is reduced c. When taken in addition to CHO, must account for additional kcal d. Typically has a negative effect on fluid balance e. Reduces core temperature when exercising in low temperatures f. Reduces ability to exercise on subsequent days g. Not recommended: 1) Prior to performance—impairs judgment 2) Binge drinking 4. Negative and positive effects of alcohol on health a. Consider amount and pattern of consumption b. Detrimental 1) Addiction, aggressive behavior, poor judgment 2) Associated with some auto accidents, homicides, suicides 3) Stroke, arrhythmias, hypertension, and other diseases when greater than moderate amounts c. Beneficial (in moderation) 1) Lower risk for cardiovascular disease, stroke, diabetes Question for discussion: A 165 lb (75 kg) athlete drinks a large (16 oz) caffeinated coffee in an effort to enhance performance. Is this an appropriate amount of caffeine? V. 10.3 Dietary supplements and ergogenic aids • Dietary supplementation decisions are a part of the athlete’s comprehensive nutrition and training plan. • Only a handful of dietary supplements have been shown to be safe and effective to improve training or performance. • For those supplements found to be effective, the impact on training and performance is likely to be small, although small effects in well-trained athletes are important to consider. • Minimal regulation of dietary supplements in the United States means that athletes must be careful when choosing supplements. A. General characteristics 1. Regulation in the U.S. is minimal (DSHEA) 2. May contain banned substances 3. Except for creatine, most have not been well studied in athletes 4. Few dose-response studies 5. Few have been shown to enhance performance (Table 10.6, page 387 Safety and Effectiveness of Selected Dietary Supplements Used by Athletes) 6. Some dietary supplements have been found to be detrimental to performance 7. There is no substitute for disciplined training and proper diet B. For those supplements that are known to be effective, the ability to enhance performance is relatively small 1. Training is likely to have the biggest impact on performance 2. Proper use and timing of nutrients also has a larger impact than most legal supplements a. Effect of most dietary supplements is estimated to be zero b. Creatine 1-2% increase estimated c. Caffeine 2-3% increase estimated d. Figure 10.22, page 389 Estimated performance improvement in various interventions 3. Illegal substances a. Anabolic steroids b. Blood doping (erythropoietin) 4. Remind athletes to investigate five critical aspects of dietary supplements a. Legality b. Ethics c. Purity d. Safety e. Effectiveness C. Practitioners should discuss dietary supplement use with athletes 1. Provide as much unbiased, scientific information as possible 2. Don’t dismiss all dietary supplements 3. People who sell supplements are not a source of unbiased information 4. Express concerns about potential side effects 5. “Guide but don’t decide” (athlete’s decision) C. Spotlight on supplements: Understanding a Dietary Supplement Label 1. Serving size 2. Amount 3. Percent Daily Value 4. Ingredient list 5. Additional information 6. Principal display panel 7. Health and structure/function claims D. Vitamin and mineral supplements are frequently used by athletes 1. Most widely used supplement by athletes 2. Benefit depends on dietary intake 3. If diet is adequate in nutrients, supplementation will not improve performance 4. May be beneficial to offset a dietary deficiency 5. Indicated for pregnant or lactating athletes E. Protein supplements are particularly popular with high school and collegiate male athletes 1. Can consume enough protein from food 2. Supplements may be convenient 3. Not more or less effective for increasing muscle mass than food proteins 4. Spotlight on supplements: Should I Take a Protein Supplement? F. Athletes typically consume herbals and botanicals to prevent or recover from illness or injury 1. Complementary and alternative medications 2. Many times used to treat illness 3. More drug-like than food-like 4. Safety varies with dose 5. Question: is it legal, ethical, safe, pure, and effective? Question for discussion: How might dietary supplementation fit into the athlete’s comprehensive training and nutrition plan? V. A comprehensive nutrition plan to support training and performance • Nutrition supports training; thus every athlete needs a comprehensive nutrition plan. • Any nutrition plan must be individualized and based on the sport and position played. A. Helping an athlete create a nutrition plan requires an understanding of the athlete’s sport and position played 1. General guidelines are made for sports with similar demands (Table 10.7, page 398) a. Very high intensity, very short duration 1) Maximal effort for < 30 sec 2) Sprinters, throwers, lifters 3) High muscularity, usually low percentage body fat b. High intensity, short duration, continuous activity 1) 30 sec to 30 min 2) Short-distance running, swimming, cycling, rowers, skaters 3) High power-to-weight ratio 4) High muscularity, relatively low percentage body fat c. High intensity, short duration, intermittent activity 1) Exercise lasting seconds or minutes with some rest periods 2) Gymnastics, wrestling, boxing, martial arts, bodybuilding 3) High power-to-weight ratio 4) High muscularity, typically low percentage body fat 5) Weight may have to be certified 6) Appearance may be influential in scoring d. Intermittent, high intensity 1) “Stop-and-go” sports 2) Soccer, basketball, hockey, tennis 3) Consider relative need for speed, strength, and power 4) Needs vary based on sport, position, area covered, frequency of substitution e. Endurance and ultraendurance 1) Continuous exercise lasting one to many hours 2) Distance running, swimming, cycling 3) Extraordinarily long events 4) Relatively low percentage body fat generally advantageous 5) Substantial nutritional demands during training and competition f. Intermittent, low intensity 1) Some maximal effort but generally low intensity for several hours 2) Golf, baseball 3) Body composition plays lesser role 2. Individualized plans are needed a. Plan should be comprehensive b. Within the same sport, individual plans may be very different B. Spotlight on a real athlete: Annika, a Collegiate Rower C. Focus on research: How Are Nutrient Recommendations for Athletes Determined? Question for discussion: Arnold Schwarzenegger, former Mr. Olympia (1970–75) and governor of California, said, “Bodybuilding is much like any other sport. To be successful you must dedicate yourself 100% to your training, diet, and mental approach.” Do you agree or disagree? X. Summary and review A. Chapter summary B. Post-test assessment C. Review questions D. References Supplementary Teaching Materials and Classroom Activities Note: The text chapter includes an application exercise requiring creation of a diet prescription and a 1-day meal plan based on MyPlate or the Food Pyramid for Athletes (p. 376). Activity 10-1 Have students create a one-day diet plan for an athlete based on MyPlate. Students can work individually or with a partner to complete this plan as an in-class or out-of-class assignment. Each student or group can be assigned or choose a kilocalorie level, but it is generally recommended that the sample diet have at least 1,800 kcal. Bringing plastic food models and measuring cups and spoons to class helps students to visualize and better understand portion sizes. Some students already have knowledge and experience using MyPlate. To make it more challenging for those students, use situations where choices are more limited. For example, have students create diets for someone who is lactose intolerant or vegan. After students have completed their diet plans, ask for volunteers to share what was created to help students recognize that two diet plans (or two meals) can be very different but contain approximately the same amount of kcal and macronutrients. Activity 10-2 Similar to Activity 10-1, have students create a plan for food and fluid intake prior to, during, and after exercise. Students can work individually, with a partner, or in a small group; this can be an in-class or out-of-class assignment. Plastic food models, measuring cups and spoons, and samples of widely used products (e.g., various sports beverages, gels, etc.) help students to visualize and better understand portion sizes. After students have completed this assignment, ask for volunteers to share what was created to help students recognize that there are a variety of ways for the athlete to meet pre-, during, and post-exercise goals. Some suggested scenarios include: • Food and fluid plan for pre-season football, 2-a-day practices • Pre-competition meal and fluid intake for a marathon starting at 7:30 a.m. • Fluid, carbohydrate, and sodium replenishment plan for a marathon • Fluid, carbohydrate, and sodium replenishment plan for a triathlon • Meal and fluid plan for a 3-day cancer walk in hot and humid conditions • Post-exercise plan for a basketball tournament • Post-weigh-in food and fluid plan for a wrestler who has just made weight Activity 10-3 Continue to have students evaluate their own 24-hour dietary intake over a period of 1 to 3 days (see Chapter 4, Activity 4-3). As the 24-hour dietary intake often serves as the basis for a term paper that evaluates dietary intake, it may be time for the paper to be due. The day the paper is due is often a good time to discuss total dietary intake, since many classroom discussions often focus on a single nutrient (e.g., CHO) or foods that are a good source of a particular nutrient. A discussion of total dietary intake gives the class an opportunity to discuss diet in its broadest context, including dietary supplements, caffeine, and alcohol consumption. Crossword Puzzle Answer Key 1. erythropoietin 2. carbohydrate 3. ergogenic 4. periodization 5. prescription 6. blood doping 7. psychotropic 8. glycerol 9. diet 10. bicarbonate loading Word Find Puzzle Answer Key • 2 macronutrients considered first in diet planning for athletes: carbohydrate, protein • 5 types of foods that are typically nutrient dense: fruits, vegetables, whole grains, beans, legumes • 2 food components that are non-nutrient dense: sugar, alcohol • 5 things intake of food/fluids during exercise should prevent or delay: hypoglycemia, fatigue, dehydration, hyponatremia, GI distress • 3 very-high-intensity, very-short-duration events: sprints, jumps, throws • 4 “stop and go” sports: soccer, basketball, football, tennis • 3 types of information found on a supplement label: quantity, percent DV, ingredients I V D T N E C R E P Y S P R I N T S H W V E G E T A B L E S I T S T N R Y I E O H S B D K K D O O W O R R G P D N N W Y S T E N S N I A R G E L O H W G Q N D R S O A T A R S E T R N T I E R U T R O S W E N B M O N F A T I G U E A O A A E N E H S J C T T G Y O B N D N T T H R O W S U E C R H U S C A O I T H I D T O S M O R E D E S T A S B E I E O S S N P E V M R O C O I T K O N T E N N I S A L I C U W R A U C E D T Y C J G D M C A R B O H Y D R A T E S T R B O I Y S O E Y P N O D F H B Y E H Y P O G L Y C E M I A S S I A A S M D O N I E T O R P I A L C O H O L E E L E G U M E S R F F F O O T B A L L D Chapter 10 Crossword Puzzle Across Down 2. A diet and exercise protocol called _____ loading is used to attain maximum glycogen stores prior to an important competition. 5. A dietary _____ is an individualized plan for an appropriate amount of kilocalories, carbohydrates, proteins, fats, and alcohol daily. 7. Capable of affecting the mind. 9. The food and drink normally consumed; the restriction of food and drink for the purpose of weight loss. 10. Consumption of sodium bicarbonate or sodium citrate prior to high-intensity exercise to neutralize the acid produced during high-intensity exercise. 1. Hormone that stimulates the development of red blood cells in the bone marrow. 3. Having the ability to generate or improve work. 4. The creation of a nutrition plan to support training that has been divided into distinct periods of time is known as nutrition _____. 6. Intravenous infusion of the athlete’s previously withdrawn blood for the purpose of increasing oxygen-carrying capacity. 8. A sugar alcohol whose ingestion results in temporary fluid retention and reduction of urine production. Chapter 10 Word Find Puzzle I V D T N E C R E P Y S P R I N T S H W V E G E T A B L E S I T S T N R Y I E O H S B D K K D O O W O R R G P D N N W Y S T E N S N I A R G E L O H W G Q N D R S O A T A R S E T R N T I E R U T R O S W E N B M O N F A T I G U E A O A A E N E H S J C T T G Y O B N D N T T H R O W S U E C R H U S C A O I T H I D T O S M O R E D E S T A S B E I E O S S N P E V M R O C O I T K O N T E N N I S A L I C U W R A U C E D T Y C J G D M C A R B O H Y D R A T E S T R B O I Y S O E Y P N O D F H B Y E H Y P O G L Y C E M I A S S I A A S M D O N I E T O R P I A L C O H O L E E L E G U M E S R F F F O O T B A L L D Instructions: In the grid above, find the following words or phrases, and then write them beside each clue. • 2 macronutrients considered first in diet planning for athletes: • 5 types of foods that are typically nutrient dense: • 2 food components that are non-nutrient dense: • 5 things intake of food/fluids during exercise should prevent or delay: • 3 very-high-intensity, very-short-duration events: • 4 “stop and go” sports: • 3 types of information found on a supplement label: 1 Crossword and word find contributed by Elesha Feldman Instructor Manual for Nutrition for Sport and Exercise Marie Dunford, J. Andrew Doyle 9781285752495