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Ex Nutr c9-Vit Mineral
Vitamins
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Water-soluble, fat-soluble
Reusable coenzymes in many metabolic
reactions
Generally, exercise ↑vitamin requirement
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↓absorption from GI tract
↑excretion from sweat
↑turnover (degradation)
↑requirement (retention) because biochemical
adaptation to training (↑ mitochondria density,
muscle hypertrophy)
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The roles of water-soluble vitamins
in energy metabolism
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Assessing vitamin status
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Difficult to determine accurately
Diagnosis of vitamin deficiency needs to
COMBINE following information
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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
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Except with extremely low dietary energy intake
or very imbalanced diet
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Recommended intakes of vitamins
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Estimated average requirement (EAR): normally
distributed
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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
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If energy intake match energy requirement, athletes
consume reasonably balanced diet, they can get all
vitamins they need from food
No need for supplements
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Risk group for low vitamin intake
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Low-energy or unbalanced diet
Very high energy intake (>4800 kcal/day)
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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
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Acute exercise may change plasma concentrations
Mainly due to redistribution of labile pools
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Effect of exercise on
mineral requirements
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Ex Nutr c9-Vit Mineral
Temporary depression of free (unbound)
plasma concentrations of some minerals after
prolonged exercise
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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
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Dietary surveys of mineral
intakes in elite athletes
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Difficult
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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
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Middle- and long-distance runners, adolescent athletes,
female athletes
Low Ca intake: female and adolescent athletes
Low Zn, Mg intake: female athletes
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Effect of exercise on
iron requirements
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Iron loss in sweat
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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
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↑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
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Iron
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Iron depletion (serum ferritin儲鐵蛋白 < 12 ug/L) common
in female athletes
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Anemia reduce athletic performance
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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
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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
Vitamin C absorption ↑ rate for nonheme-iron
Anemia also result from deficiency in B6, B12, folate
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For nucleic acid and red blood cell production
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Phytate: 植酸; Tannins: 單寧酸; phosphate 磷酸根
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Calcium and bone health
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Ca intake closely related to total-energy intake
Female athlete triad: amenorrhea, oligomenorrhea
associated with high risk of early osteoporosis
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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
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Lost 4 L sweat  lost 2 mmol (80 mg) Ca  200 mg Ca
intake (40% absorption)
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Micronutrients as antioxidants
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Exercise ↑free radical (unpaired electron) production
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Antioxidant defense system eliminate/quench free radicals
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Demonstrated in vivo studies
Mainly through electron leakage from electron transport chain, 3-5%
oxygen consumed at rest
Damage to lipid, protein, DNA
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
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Antioxidant and muscle damage
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Unaccustomed exercise or eccentric actions damage
myofibers
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Muscle pain, soreness, stiffness, ↓range of motion,
↓glycogen resynthesis
Damaged muscle tissue cause initial activation of
immune system
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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
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Antioxidant mechanisms
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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?
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Vitamin C
beta-carotene
Vitamin E
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Polyphenols
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Regeneration of GSH
Glutathione
(GSH)
Glutathione
reductase
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Possible risks of high-dose
antioxidant supplementation
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Antioxidants inhibit apoptosis (programmed cell
death)
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In situations with high DNA damage
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Important defense mechanism, inhibit tumor
development by eliminating new mutated cells
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
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Usually NO effect on exercise performance
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Athletes need more antioxidants?
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Higher antioxidant required in athletes to reduce
oxidative damage induced by exercise
Dietary sources of antioxidants are preferable to
single/combined supplements
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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
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