Table 1.
Proposed nutritional ergogenic aids – vitamins
| Nutrient | RDA | Proposed ergogenic value | Summary of research findings |
|---|---|---|---|
| Vitamin A | Males 900 mcg/d Females 700 mcg/d |
Constituent of rhodopsin (visual pigment) and is involved in night vision. Some suggest that vitamin A supplementation may improve sport vision. | No studies have shown that vitamin A supplementation improves exercise performance [139]. |
| Vitamin D | 5 mcg/d (age < 51) | Promotes bone growth and mineralization. Enhances calcium absorption. Supplementation with calcium may help prevent bone loss in osteoperotic populations. | Co-supplementation with calcium may help prevent bone loss in athletes susceptible to osteoporosis [707]. However, vitamin D supplementation does not enhance exercise performance [139]. |
| Vitamin E | 15 mg/d | As an antioxidant, it has been shown to help prevent the formation of free radicals during intense exercise and prevent the destruction of red blood cells, improving or maintaining oxygen delivery to the muscles during exercise. Some evidence suggests that it may reduce risk to heart disease or decrease incidence of recurring heart attack. | Numerous studies show that vitamin E supplementation can decrease exercise-induced oxidative stress [708–710]. However, most studies show no effects on performance at sea level. At high altitudes, vitamin E may improve exercise performance [711]. Additional research is necessary to determine whether long-term supplementation may help athletes better tolerate training. |
| Vitamin K | Males 120 mcg/d Females 90 mcg/d |
Important in blood clotting. There is also some evidence that it may affect bone metabolism in postmenopausal women. | Vitamin K supplementation (10 mg/d) in elite female athletes has been reported to increase calcium-binding capacity of osteocalcin and promoted a 15–20% increase in bone formation markers and a 20–25% decrease in bone resorption markers suggesting an improved balance between bone formation and resorption [712]. |
| Thiamin (B1) | Males 1.2 mg/d Females 1.1 mg/d |
Coenzyme (thiamin pyrophosphate) in the removal of CO2 from decarboxylic reactions from pyruvate to acetyl CoA and in TCA cycle. Supplementation is theorized to improve anaerobic threshold and CO2transport. Deficiencies may decrease efficiency of energy systems. | Dietary availability of thiamin does not appear to affect exercise capacity when athletes have a normal intake [713]. |
| Riboflavin (B2) | Males 1.3 mg/d Females 1.7 mg/d |
Constituent of flavin nucleotide coenzymes involved in energy metabolism. Theorized to enhance energy availability during oxidative metabolism. | Dietary availability of riboflavin does not appear to affect exercise capacity when athletes have a normal intake [713]. |
| Niacin (B3) | Males 16 mg/d Females 14 mg/d |
Constituent of coenzymes involved in energy metabolism. Theorized to blunt increases in fatty acids during exercise, reduce cholesterol, enhance thermoregulation, and improve energy availability during oxidative metabolism. | Studies indicate that niacin supplementation (100–500 mg/d) can help decrease blood lipid levels and increase homocysteine levels in hypercholesteremic patients [714, 715]. However, niacin supplementation (280 mg) during exercise has been reported to decrease exercise capacity by blunting the mobilization of fatty acids [716]. |
| Pyridoxine (B6) | 1.3 mg/d (age < 51) | Has been marketed as a supplement that will improve muscle mass, strength, and aerobic power in the lactic acid and oxygen systems. It also may have a calming effect that has been linked to an improved mental strength. | In well-nourished athletes, pyridoxine failed to improve aerobic capacity, or lactic acid accumulation [713]. However, when combined with vitamins B1and B12, it may increase serotonin levels and improve fine motor skills that may be necessary in sports like pistol shooting and archery [717, 718]. |
| Cyano-cobalamin (B12) | 2.4 mcg/d | A coenzyme involved in the production of DNA and serotonin. DNA is important in protein and red blood cell synthesis. Theoretically, it would increase muscle mass, the oxygen-carrying capacity of blood, and decrease anxiety. | In well-nourished athletes, no ergogenic effect has been reported. However, when combined with vitamins B1 and B6, cyanocobalamin has been shown to improve performance in pistol shooting [718]. This may be due to increased levels of serotonin, a neurotransmitter in the brain, which may reduce anxiety. |
| Folic acid (folate) | 400 mcg/d | Functions as a coenzyme in the formation of DNA and red blood cells. An increase in red blood cells could improve oxygen delivery to the muscles during exercise. Believed to be important to help prevent birth defects and may help decrease homocysteine levels. | Studies suggest that increasing dietary availability of folic acid during pregnancy can lower the incidence of birth defects [719]. Additionally, it may decrease homocysteine levels (a risk factor for heart disease) [720]. In well-nourished and folate deficient-athletes, folic acid did not improve exercise performance [721]. |
| Pantothenic acid | 5 mg/d | Acts as a coenzyme for acetyl coenzyme A (acetyl CoA). This may benefit aerobic or oxygen energy systems. | Research has reported no improvements in aerobic performance with acetyl CoA supplementation. However, one study reported a decrease in lactic acid accumulation, without an improvement in performance [722]. |
| Beta carotene | None | Serves as an antioxidant. Theorized to help minimize exercise-induced lipid peroxidation and muscle damage. | Research indicates that beta carotene supplementation with or without other antioxidants can help decrease exercise-induced peroxidation. Over time, this may help athletes tolerate training. However, it is unclear whether antioxidant supplementation affects exercise performance [709]. |
| Vitamin C | Males 90 mg/d Females 75 mg/d |
Used in a number of different metabolic processes in the body. It is involved in the synthesis of epinephrine, iron absorption, and is an antioxidant. Theoretically, it could benefit exercise performance by improving metabolism during exercise. There is also evidence that vitamin C may enhance immunity. | In well-nourished athletes, vitamin C supplementation does not appear to improve physical performance [138, 723]. However, there is some evidence that vitamin C supplementation (e.g., 500 mg/d) following intense exercise may decrease the incidence of upper respiratory tract infections [696, 724, 725]. |
Recommended Dietary Allowances (RDA) based on the 1989 Food & Nutrition Board, National Academy of Sciences-National Research Council recommendations. Updated in 2001