Ex Nutr c9-Vit Mineral1 Vitamins Water-soluble, fat-soluble Reusable coenzymes in many metabolic reactions Generally, exercise ↑vitamin requirement ↓absorption

Ex Nutr c9-Vit Mineral 1

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 6The roles of water-soluble vitamins in energy metabolism


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


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



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 20Effect 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 21Dietary 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 22Effect 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


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



Phytate: 植酸 ; Tannins: 單寧酸 ; phosphate 磷酸根


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)




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


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


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?


Vitamin C

Vitamin Ebeta-carotene


Polyphenols



Regeneration of GSH

Glutathione reductase

Glutathione

(GSH)

Ex Nutr c9-Vit Mineral 36Possible 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


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





Documents

Ex Nutr c9-Vit Mineral1 Vitamins Water-soluble, fat-soluble Reusable coenzymes in many metabolic reactions Generally, exercise ↑vitamin requirement ↓absorption