People who participate in recreational and sports activities generally are aware of the importance of diet and nutrition in physical performance. Sound scientific evidence to support the use of some supplements is available specifically for water, carbohydrate and protein. Evidence of the need for increased vitamin intake among physically active people is lacking. Only people with biochemical evidence of depleted mineral elements benefit from use of appropriate supplements. Indiscriminate use of individual mineral supplements can promote nutritional deficiencies of other minerals. Two dietary supplements, chromium (Cr) and creatine (CRTN), recently have been promoted as being able to boost performance. Chromium has recently been shown to facilitate the action of insulin which is an ergogenic agent. However, humans supplemented with 200 micrograms of Cr as Cr picolinate showed no benefit in strength development and body composition (loss of body fat and gain of muscle mass). CRTN is a key component of phosphocreatine (PCRTN), an immediate source of energy and replenisher of the energy molecule adenosine triphosphate in the cell. CRTN loading increases muscular stores of PCRTN and enhances strength gain by promoting increased training and facilitating recovery after heavy training. Adverse effects of long term supplementation of CRTN are not available. The general recommendation is to avoid the use of nutritional supplements unless under the guidance of a physician or a licensed dietitian. Emphasis should be on the consumption of a diet containing a variety of foods with high vitamin and mineral nutrient content. This information will be useful to nutritionists who study the effects of diet on physical performance and who counsel physically active people.
© Copyright 1999 Proceedings of the National Academy of Sciences of the United States of America. Stanford University's Highwire Press. Alle Rechte vorbehalten.