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Vitamins. Water-soluble, fat-soluble Reusable coenzymes in many metabolic reactions Generally, exercise ↑vitamin requirement ↓ absorption from GI tract ↑excretion from sweat ↑turnover (degradation)
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Ex Nutr c9-Vit Mineral Vitamins • Water-soluble, fat-soluble • Reusable coenzymes in many metabolic reactions • Generally, exercise ↑vitamin requirement • ↓absorption from GI tract • ↑excretion from sweat • ↑turnover (degradation) • ↑requirement (retention) because biochemical adaptation to training (↑ mitochondria density, muscle hypertrophy)
Ex Nutr c9-Vit Mineral The roles of water-soluble vitamins in energy metabolism
Ex Nutr c9-Vit Mineral Assessing vitamin status • Difficult to determine accurately • Diagnosis of vitamin deficiency needs to COMBINE following information • Blood analysis: plasma concentration and/or activity of functional enzyme(s) • Dietary intake: tedious and inaccurate • Clinical symptoms: unspecific • Most studies showed that athletes do NOT have lower vitamin status • Except with extremely low dietary energy intake or very imbalanced diet
Ex Nutr c9-Vit Mineral Recommended intakes of vitamins • Estimated average requirement (EAR): normally distributed • Amount of nutrient sufficient to meet the needs of average individual in certain age and gender • Recommended daily allowance (RDA): cover 97.5% of all healthy individuals • Athletes have higher requirement for vitamins, but also consume more foods/energy • If energy intake match energy requirement, athletes consume reasonably balanced diet, they can get all vitamins they need from food • No need for supplements
Ex Nutr c9-Vit Mineral Risk group for low vitamin intake • Low-energy or unbalanced diet • Very high energy intake (>4800 kcal/day) • Consume large ‘in between meals’ and high-energy sport drinks • Low in vitamins/minerals • Vegetarians: B12 • Vitamin loss in sweat negligible • NO increased vitamin excretion in urine and feces in athletes • Vitamin turnover usually unaffected by exercise • Acute exercise may change plasma concentrations • Mainly due to redistribution of labile pools
Ex Nutr c9-Vit Mineral Effect of exercise on mineral requirements • Temporary depression of free (unbound) plasma concentrations of some minerals after prolonged exercise • Fe, Zn, Cu • Redistribution of different tissue compartments • Release of proteins from liver/neutrophils that chelate (螯合) minerals, part of acute-phase response to inflammation
Ex Nutr c9-Vit Mineral Dietary surveys of mineral intakes in elite athletes • Difficult • Differences in bioavailability in various foods • Not all foods have analyzed for their mineral contents • Mineral contents may depend on their content in soil • Plasma concentrations usually do NOT represent body pool • Low iron stores • Middle- and long-distance runners, adolescent athletes, female athletes • Low Ca intake: female and adolescent athletes • Low Zn, Mg intake: female athletes
Ex Nutr c9-Vit Mineral Effect of exercise on iron requirements • Iron loss in sweat • Previous studies: can reach 0.3 mg/L Extra ~12 mg iron from food (10% absorbed) • Recent studies: 6-11% iron absorbed each day lost in sweat per hour of exercise • Higher sweat rate and higher iron loss in men • Increased iron requirement • ↑Myoglobin, red cell mass • GI bleeding: irritation of stomach lining or hemorrhage of colon caused by ischemia • Elite male distance runners loss 6 ml blood/day from GI during training and racing
Ex Nutr c9-Vit Mineral Iron • Iron depletion (serum ferritin儲鐵蛋白 < 12 ug/L) common in female athletes • Iron depletion without anemia ↑lactate during max exercise, ↑subjective feeling of exercise overload in elite athletes • ↑performance by iron supplementation in Iron depletion without anemia • Anemia reduce athletic performance • Insufficient oxygen delivery, breathlessness, mental dysfunction, impaired temperature control, ↓immunity • Periodic screening of serum ferritin in athletes • Higher absorption rate for heme 血基質-iron • Vitamin C absorption ↑ rate for nonheme-iron • Anemia also result from deficiency in B6, B12, folate • For nucleic acid and red blood cell production
Ex Nutr c9-Vit Mineral Phytate: 植酸; Tannins: 單寧酸; phosphate 磷酸根
Ex Nutr c9-Vit Mineral Calcium and bone health • Ca intake closely related to total-energy intake • Female athlete triad: amenorrhea, oligomenorrhea associated with high risk of early osteoporosis • Chronically low estrogen • Low body fat, low energy intake, high physical activity • Eating disorder • Gymnastics, swimming, long-distance running, dancers • ↑Ca consumption to 120% RDA help maintain bone density and development in amenorrhea • Use low-fat dairy products • Sweat concentration 0.1-1.0 mM • Lost 4 L sweat lost 2 mmol (80 mg) Ca 200 mg Ca intake (40% absorption)
Ex Nutr c9-Vit Mineral Micronutrients as antioxidants • Exercise ↑free radical (unpaired electron) production • Demonstrated in vivo studies • Mainly through electron leakage from electron transport chain, 3-5% oxygen consumed at rest • Damage to lipid, protein, DNA • Antioxidant defense system eliminate/quench free radicals • Prevent/reduce oxidative stress • Vitamin C, E, beta-carotene • Cu, Zn, Selenium: as cofactors for antioxidant enzymes • Glutathione: glycine, cysteine, glutamine • Polyphenols 多酚類: tea, red wine, fruits, vegetables
Ex Nutr c9-Vit Mineral Antioxidant and muscle damage • Unaccustomed exercise or eccentric actions damage myofibers • Muscle pain, soreness, stiffness, ↓range of motion, ↓glycogen resynthesis • Damaged muscle tissue cause initial activation of immune system • WBC attracted to damaged muscle breakdown of damaged fibers, initiate repair process • Occur within fist hour after eccentric exercise, followed by infiltration of monocyte and macrophage, reaching max at 24-72 after exercise • Repaired process involve production of reactive oxygen species (ROS) by invading leukocytes • ROS cause muscle soreness, ↑creatine kinase, oxidative damage to DNA and proteins
Ex Nutr c9-Vit Mineral Antioxidant mechanisms • Prevent ROS formation • Intercept ROS attack by scavenging • Binding transition metal ion, such as Cu, Fe, to prevent initiation of free radical reactions • React with chain-propagating radicals • Provide favorable environment for effective functioning of other antioxidants • Free radical really a bad thing? Or a signal for exercise adaptation?
Ex Nutr c9-Vit Mineral Vitamin C beta-carotene Vitamin E
Ex Nutr c9-Vit Mineral Polyphenols
Ex Nutr c9-Vit Mineral Regeneration of GSH Glutathione (GSH) Glutathione reductase
Ex Nutr c9-Vit Mineral Possible risks of high-doseantioxidant supplementation • Antioxidants inhibit apoptosis (programmed cell death) • Important defense mechanism, inhibit tumor development by eliminating new mutated cells • In situations with high DNA damage • Exercise, heavy smoking • Administration of large amounts of antioxidants may prevent effective removal of damaged cells • May ↑cancer risk • Insufficient data to recommend antioxidant supplements for athletes • Usually NO effect on exercise performance
Ex Nutr c9-Vit Mineral Athletes need more antioxidants? • Higher antioxidant required in athletes to reduce oxidative damage induced by exercise • Dietary sources of antioxidants are preferable to single/combined supplements • Based on epidemiological studies on adverse health outcomes • Pro-oxidant effects with prolonged use of high-dose antioxidant supplements • May need 3X of RDI • Supplements may be necessary if RDI can not be met • Antioxidant supplements on human performance usually negative
