Vitamins and Exercise Performance

Just for Nutrition or Are they Performance Enhancers Also?

Vitamins

n Basic Facts

n Vitamins are organic compounds that are essential for optimal physiological functioning

n Functions

n Coenzyme functions – help in activation of enzymes

n Antioxidant functions – help enzymes lessen effect of free radicals

n Hormone functions – important in formation of certain hormones

n Energy – vitamins do not serve as an energy source

Vitamins

n More Basic Facts

n 13 different “essential” vitamins

n 4 are fat-soluble

n 9 are water-soluble

n There are several other “vitamin-like” substances talked about in relation to exercise performance, but are not vitamins

n Inositol, PABA, Vit B₁₅ (pangamic acid), Vit₁₇ (laetrile)

n Bee pollen, coenzyme Q₁₀, ginseng, ginkgo

Vitamins

n Magnitudes of Deficiency

n Preliminary stage

n Inadequate amount in diet (bioavailability)

n Biochemical deficiency

n Body’s pool of a particular vitamin is decreased

n Physiological deficiency

n Symptoms of vitamin deficiency appear; i.e. loss of appetite, weakness, physical fatigue

n Clinically manifested vitamin deficiency

n Specific clinical symptoms observed; i.e. anemia, where health and performance are adversely affected

Fat-Soluble Vitamins

n Basic Facts

n 4 fat-soluble vitamins

n Some can be made in body; also stored in body

n Deficiencies are rare in industrialized populations

n Excessive amounts may be toxic

Fat-Soluble Vitamins

n Vitamin A (retinol)

n RDA is 900 RAE (4,500 IU) for males; 700 RAE (3,500 IU) for females

n Food sources – animal foods & dark green or yellow-orange vegetables

n Major function – essential for epithelial cell formation, vision, immune function

n Deficiency – loss of night vision, infections

n Supplementation – may cause several health problems in excess; i.e. birth defects

n Performance Effect – does not improve performance in endurance runners through ↑ gluconeogenesis

Fat-Soluble Vitamins

n Vitamin D (cholecalciferol)

n AI (adequate intake) is 5 ug (200 IU) per day

n Food sources – fish liver oils, eggs, tuna, salmon, or fortified foods; most foods do have Vitamin D so need exposure to sunlight

n Major function – important for bone and skin metabolism

n Deficiency – bone loss (osteomalacia –softer bones)

n Supplementation – may cause damage to soft tissues due to calcium deposits

n Performance Effect – does not improve bone mass in athletes

Fat-Soluble Vitamins

n Vitamin E (alpha-tocopherol)

n RDA is 15 mg (200 IU) per day

n Food sources – polyunsaturated vegetable oils (corn, soybean, safflower) and fortified cereals

n Major function – antioxidant in cell membrane (prevention of cell membrane destruction)

n Deficiency – may have damage to soft tissues (skeletal muscle, heart, blood vessels)

n Supplementation – does not appear to have significant deleterious effects

n Performance Effect – shown to enhance aerobic capacity (VO₂ max) and improve anaerobic threshold in altitude studies; otherwise, not effective

Fat-Soluble Vitamins

n Vitamin K (phylloquinone; menoquinone)

n AI is 120 ug for men; 90 ug for women per day

n Food sources – vegetable oils (soybean, olive) and green and leafy vegetables

n Major function – blood clotting & strengthen bones

n Deficiency – impairment of blood clotting; osteoporosis

n Supplementation – does not appear to have significant deleterious effects

n Performance Effect – not effective in improving performance but may be helpful to bone health of female athletes

Water-Soluble Vitamins

n Basic Facts

n 9 water-soluble, 8 of which are in B-complex

n Not stored in the body

n Deficiency effects may appear within 2-4 weeks

Water-Soluble Vitamins

n Thiamin (Vitamin B₁)

n RDA is 1.2 mg for men; 1.1 for women per day

n Food Sources – whole grain cereals, beans, pork, fortified (added 1 or more nutrients other than found in natural amount) cereals

n Major function – metabolism of glucose; high intensity, endurance activity increases need for thiamin

n Deficiency – may result in loss of appetite, mental confusion, muscle weakness, pain in calf muscles

n Supplementation – no evidence of toxicity

n Performance – overall, not shown to improve muscle strength or endurance; however, shown to reduce subjective feelings of fatigue; proposed to improve pistol shooting

Water-Soluble Vitamins

n Riboflavin (Vitamin B₂)

n RDA is 1.3 mg for men; 1.1 for women per day

n Food Sources – milk, whole grain cereals, dark green leafy vegetables, enriched (contain B₁, B₂, niacin, & iron) cereals

n Major function – formation of oxidative enzymes for energy production from CHO & fats; also protein metabolism

n Deficiency – may result in inflammation of tongue, dry scaly skin; women beginning aerobic training program may need extra

n Supplementation – no evidence of toxicity

n Performance – not shown to improve performance, particularly with distance swimmers

Water-Soluble Vitamins

n Niacin (not Vitamin B₃)

n RDA is 16 NE/day (niacin equiv) for men; 14 NE for women

n Food Sources – lean meats, whole grain cereals, legumes (bean & peanuts), enriched (contain B₁, B₂, niacin, & iron) cereals

n Major function – component of coenzymes for glycogen breakdown and fat synthesis

n Deficiency – may result loss of appetite, skin rashes, mental confusion, lack of energy, muscle weakness

n Supplementation – not considered toxic but large doses may cause flushing, burning, tingling sensations

n Performance – may lessen performance in endurance athletes due to blocking of FFA release from adipose tissue, hence more rapid depletion of glycogen in muscle; may be helpful in temperature regulation in hot environment

Water-Soluble Vitamins

_n Vitamin B₆ (pyridoxine)

n RDA is 1.3 mg/day (ages 10-50 years); higher amount in later years

n Food Sources – lean meats, whole grain cereals, brown rice, eggs

n Major function – important in CHO, fat, and protein metabolism

n Deficiency – may result nausea, impaired immune function, skin disorders, weakness, mental depression, anemia; exercise does not cause excessive loss of B₆

n Supplementation – may be associated with some health risks, ie. nerve damage, if consumed in large doses over time

_n Performance – not been shown to influence performance of endurance athletes; exercise may actually promote storage of Vitamin B₆

Water-Soluble Vitamins

_n Vitamin B₁₂ (cobalamin)

n RDA is 2.4 ug/day for average adult

n Food Sources – lean meats, cheese, eggs, milk; minimal amount in plant sources

n Major function – important in formation of DNA, RBC’s, and protective sheath of nerve fibers

n Deficiency – may result anemia and/or nerve damage; needed particularly in pregnant women to prevent birth defects

n Supplementation – large doses are considered relatively harmless; since it helps prevent anemia, it is theorized to improve aerobic performance; a form of B₁₂ (Dibencobal) is theorized to increase muscle growth and strength

n Performance – not been shown to influence performance of endurance athletes or body builders

Water-Soluble Vitamins

_n Folate (folic acid)

n RDA is 400 ug/day of DFE (Dietary Folate Equivalents) for average adult; increased to 600 ug/day during pregnancy

n Food Sources – green, leafy vegetables, organ meats (liver and kidney), dry beans, whole-grain products, oranges, bananas

n Major function – important in formation of DNA, RBC’s, important in early stages of pregnancy for development of baby

n Deficiency – may result in impaired DNA formation and adverse neural and vascular effects; also anemia; large alcohol consumption and use of oral contraceptives may impair absorption of folate; may be related to cancer development; needed particularly in pregnant women to prevent birth defects

n Supplementation – megadoses could mask a Vitamin B₁₂ deficiency preventing anemia, but cover up need of B₁₂ for prevention of nerve damage; theorized to be necessary for distance runners who train vigorously resulting in destruction of RBC’s

n Performance – not been shown to influence performance of endurance runners

Water-Soluble Vitamins

_n Pantothenic acid

n AI is 5 mg/day for adults; less for young, more for pregnancy

n Food Sources – organ meats (liver and kidney), eggs, whole-grain products, legumes, yeasts

n Major function – important in energy metabolism for acetyl CoA formation; form glucose; breakdown fats; modify proteins; synthesize acetylcholine (neurotransmitter)

n Deficiency – not readily seen in humans, but symptoms are fatigue, muscle cramping, impaired motor performance are possible

n Supplementation – large doses are relatively nontoxic; theorized to be improve aerobic metabolism by improving use of O₂ and less lactate accumulation

n Performance – research is equivocal (some suggest a benefit and others do not); possible benefit to endurance athletes

Water-Soluble Vitamins

n Biotin

n AI is 30 ug/day for adults; less for young, more for lactation (post-pregnancy)

n Food Sources – organ meats (liver and kidney), egg yolks, legumes, green leafy vegetables

n Major function – important in amino acid metabolism; making glucose and fatty acids

n Deficiency – rare but symptoms are loss of appetite, mental depression, dermatitis, and muscle pain

n Supplementation – megadoses seem harmless; lacking research in this area

n Performance – no evidence to show its benefits or detriments

Water-Soluble Vitamins

n Vitamin B complex

n Deficiency – results in significant reduction of endurance capacity

n Supplementation – helpful primarily when diet is deficient in Vitamin B complex

n Performance – large doses of B₁, B₆, and B₁₂ may improve fine motor control and performance in pistol shooting due to development of neurotransmitters that induce relaxation; may be helpful in sport with high energy expenditures

Water-Soluble Vitamins

n Vitamin C (ascorbic acid)

n RDA is 90 mg/day for adult males; 75 mg/day for adult females; smaller amount for children; greater during pregnancy and lactation

n Food Sources – fruits (citrus), green leafy vegetables

n Major function – makes mineral ions more active; synthesis of collagen; formation of hormones, RBC’s, folic acid, cholesterol, a.a.; healing wounds; powerful antioxidant

n Deficiency – rare but could result in scurvy (disintegration of connective tissue) with symptoms of bleeding gums, rupture of blood vessels in skin, impaired wound healing, muscle cramps, and weakness; anemia

n Supplementation – megadoses may produce undesirable effects; may lessen severity of common cold but more research is necessary; may help prevent cardiovascular disease and cancer; individuals prone to kidney stones should avoid megadoses; many studies show not significant risks with megadoses; so supplementation recommendations remain equivocal

n Performance – does not increase performance in individuals who are not deficient in Vitamin C; may have benefit in heat acclimation or detriments

Vitamin Supplements: Ergogenic Aspects

n Should physically active individuals take vitamin supplements?

n For athletes who have energy intakes below 1,200 to 1,600 Calories/day

n In general, athletes who consume a balanced diet do not gain an advantage in performance when taking extra vitamins

Vitamin Supplements: Ergogenic Aspects

n Can antioxidant vitamins prevent muscle damage during exercise training?

n Chronic exercise training can increase the activity of antioxidant enzymes (superoxide dismutase and glutathione peroxidase)

n Most studies suggest that there is a reduction in the markers for muscle tissue damage

n Markers include: creatine kinase (CK), lactic acid dehydrogenase (LDH), and malondialdehyde (MDA, an end-product of fat breakdown from membranes)

Vitamin Supplements: Ergogenic Aspects

n The U.S.O.C. has made the following recommendations for athletes considering antioxidant vitamin intakes:

n Beta-carotene 3-20 mg/day

n Vitamin C 250-1,000 mg/day

n Vitamin E 150-400 IU/day (difficult to

obtain this entirely through

dietary sources)

Vitamin Supplements: Ergogenic Aspects

n How effective are special vitamin supplements marketed to athletes?

n Multivitamin-mineral supplements (1,000-6,000% of RDA)

n Do not provide any significant enhancement of athletic performance in well-nourished athletes

n Bee pollen

n It is a mixture of vitamins, minerals, a.a., & other nutrients

n Advertisements suggest enhancement of aerobic performance and faster recovery from exercise

§ Not been proven by well-designed studies

n Should use caution with supplementing individuals who may experience allergic reactions

Vitamin Supplements: Ergogenic Aspects

n How effective are special vitamin supplements marketed to athletes?

n Vitamin B₁₅ (not considered a vitamin)

n No specific disease state is associated with its deficiency

n No benefits in improving aerobic performance so not recommended for physically active individuals

Vitamin Supplements: Ergogenic Aspects

n How effective are special vitamin supplements marketed to athletes?

_n CoQ₁₀

n Found in mitochondria and helps in aerobic generation of ATP

_n May be beneficial in treating cardiovascular disease since it is suggested to protect heart tissue from damage due to lack of O₂

n Theorized to be of benefit in athletes since:

§ Improves heart function in cardiac patients

§ CoQ₁₀ levels have been shown to be lower in trained athletes

n Some studies suggest that it improves endurance performance

§ Combining CoQ₁₀ with Vit E, inosine, and cytochrome C, particularly in triathletes has not been proven to benefit performance

n May actually be ergolytic since it may produce more free radicals than usual and hence damage mitochondria

n Not recommended for physically active individuals

Vitamin Supplements: Ergogenic Aspects

n How effective are special vitamin supplements marketed to athletes?

n Ginseng

n Believed to influence neural and hormonal activity in the body; stimulates hypothalamus which controls pituitary gland (releases hormones that may stimulate adrenal gland to release cortisol; cortisol is may lessen sensation of stress)

§ From Russian studies, it was suggested as a physical and mental stress reducer

§ Suggest that athletes can train more intensely and not fatigue as quickly

n No proven benefits for aerobic performance

n Shown to improve multi-choice reaction time before and during a cycling exercise; i.e. reaction time

n Caution

§ Has relatively low acute or chronic toxicity, however abusive use has been associated with high blood pressure, nervousness, and sleeplessness

§ May be attributed to ephedrine as a commercial additive to ginseng

Vitamin Supplements: Ergogenic Aspects

n How effective are special vitamin supplements marketed to athletes?

n Ciwujia (similar to ginseng)

n Marketed to endurance athletes

§ Suggested to increase fat oxidation, increase VO₂, reduce lactate accumulation, and improve HR recovery from exercise

n Not been proven to be effective for aerobic performance; not recommended for endurance athletes

Summary

n There is not a strong case for supporting an ergogenic effect of any single vitamin, vitamin-mineral combinations, or various vitamin-like compounds

n The potential benefit of Vitamin E for exercise performance at altitude deserves more research

n Obtain vitamin nutrition through well-planned diet

n A typical one-a-day supplement containing 50-150% of the RDA for all vitamins and minerals may be recommended

n Definition note:

n Megadose generally refers to an amount 10 times the RDA, except for Vitamin A (only 5 times RDA) and Vitamin D (only 2 times RDA)