| Vitamin | Function(s) | Food Sources | Claim(s) of Supplements | The Science |
| A | Promotes healthy skin; essential for normal colour vision | Vegetables and fruit; butter and margarine; liver and meat; eggs; whole milk and cheese; oily fish | Maintains normal vision, healthy skin and mucous membranes | Not involved in energy production; little evidence to suggest it can improve sporting performance |
| B1 (Thiamine) | Involved in release of energy from carbohydrate; used for the normal functioning of nerves, brains and muscles | Wholemeal bread and wholegrain cereals; beans, lentils and peas; pork; fruit; fortified breakfast cereals | May optimise energy production and performance | Involved in energy production; increased needs of athletes can normally be met in the diet; evidence doesn't suggest that high intakes enhance performance |
| B2 (Riboflavin) | Involved in energy release, especially from fat and protei n | Liver; milk, cheese and yoghurt; eggs; fortified breakfast cereals; green vegetables | May optimise energy production | Although exercise may increase the body's requirements, higher demands can usually be met through diet |
| Niacin | Helps to convert carbohydrates into energy | Liver, kidneys and red meat; chicken and turkey; nuts; milk, yoghurt, cheese; eggs; bread; fortified breakfast cereals | Runners need more because it's involved in metabolism | Not enough evidence to prove that high doses can help to improve performance; requirements can be met by a balanced diet |
| B6 (Pyridoxine) | Involved in metabolism of proteins, fats and carbohydrates | Widely distributed in foods; potatoes; beef; fish; poultry; nuts; breakfast cereals | Runners need more to meet their increased energy requirements | Not enough evidence to prove that high doses can help to improve performance; requirements can be met by a balanced diet |
| Pantothenic acid | Involved in metabolism of proteins, fats and carbohydrates | Liver; wholemeal bread; brown rice; nuts; eggs; vegetables | Runners need more because it's involved in metabolism | No evidence suggests high doses improve performance |
| Folic acid (B vitamin) | Essential in the formation of DNA; necessary for red blood cell manufacture | Liver; green vegetables; wheatgerm | Helps overall well-being | No studies have been carried out on athletic performance and folic acid |
| B12 | Necessary for proper formation of blood cells | Meat; fish; eggs; fortified cereals | Can improve the body's oxygen-carrying capacity and enhance its aerobic performance; athletes have been known to use injections of B12 before competition in the hope that it will improve endurance | Extra B12 has no effect on endurance or strength |
| Biotin | Involved in the manufacture of fatty acids and glycogen, and in protein metabolism | Egg yolk; liver; nuts; wholegrains; oats | Although once known as the 'dynamite vitamin' among body builders, no specific role for biotin in sporting performance has been claimed | The body can make its own biotin, so supplements aren't necessary |
| C | Needed for production of collagen which is used in the structure of connective tissue and bones; promotes healthy blood vessels, gums and teeth | Fresh fruits, especially citrus fruits, berries and currants; dark green leafy vegetables, tomatoes and peppers | May help to increase oxygen uptake and aerobic energy production; intensive exercise tends to cause greater connective tissue damage, so runners need higher doses | A deficiency lowers levels of physical performance, so an adequate intake is important. Exercise may increase requirements, yet these can be met by diet |
| D | Controls absorption of calcium and phosphate; essential for healthy bones and teeth | Fish oils and oily fish; eggs; fortified cereals; sunshine | n/a | Not so far shown to be beneficial to performance |
| E | Protects tissues against damage; promotes normal growth and development | Vegetable oils; wheatgerm; wholemeal bread; cereals; egg yolk; nuts; dark green, leafy vegetables | May improve oxygen utilisation in the muscle cells | Studies show supplements can have a beneficial effect on performance at high altitudes |
| Information obtained from: Runner's World archives, Boots, Solgar Vitamins, the British Nutrition Foundation and The Complete Guide to Sports Nutrition by Anita Bean. |
