Good nutrition is necessary for good performance and optimal nutrition can make the difference in a championship performance. Optimal nutrition, however, is the result of good dietary habits and is not achieved by following a special diet for several days or by consuming a special food or supplement. Ergogenic aids can be categorized as mechanical, psychological and psychophysiologic, pharmacologic, and nutritional. The category of nutritional ergogenic aids includes special dietary regimens, special foods, and supplements. Of these, supplements, especially vitamins, pseudovitamins, and nonvitamins, are the most widely used. Supplements promoted as vitamins are more realistically described as vitamins, pseudovitamins, and nonvitamins. Pseudovitamins do have some activity related to vitamins, but at present no evidence exists for their requirement by humans. Nonvitamins are substances that may be found in naturally occurring foods but have no demonstrated nutritional value and are therefore not considered essential nutrients for humans or animals. Nutritional deficiencies can result in decreased performance. However, there is no evidence that consumption of nutrients beyond the requirements of the organism is beneficial and, in fact, some nutrients ingested at high levels for long periods of time result in toxicity. A review of the literature reveals that deterioration of physical performance resulting from prolonged vitamin deficiency is well documented. Numerous studies substantiate that once vitamin requirements are met, there appears to be no value in consuming additional amounts. Unfortunately, the literature is not as complete regarding vitamin or mineral toxicity. However, there is ample evidence to show that the possibility of toxicity is a genuine concern. Supplementation is common among athletes, with reported occurrence ranging from 54 to 84 per cent. Studies on the general public place the incidence of supplementation between 40 and 67 per cent. Although some dietary studies of athletes report the frequency of use of supplementation, few report the levels being consumed. A study currently in progress has found world-class amateur and professional athletes to use supplements at an incidence comparative to that reported in other studies of athletes. However, the levels at which supplements were taken are considered extremely high. Maintaining ideal weight and variety are the quantity and quality indexes for diet. Following sound nutritional principles will help to insure the athlete's ability to perform at his or her best. In general, a diet that provides 45 to 55 per cent of the calories from carbohydrate, 12 to 15 pr cent from protein, and 30 to 40 per cent from fat will meet the athlete's needs.(ABSTRACT TRUNCATED AT 400 WORDS)
