Use of nutritional supplements in sports: risks, knowledge, and behavioural-related factors.

A large number of recreational and elite athletes use nutritional supplements in hopes of improving performance. These aids can be costly and potentially harmful, and the advertised ergogenic gains are often based on little or no scientific evidence. Due to the lack of regulation of the dietary supplement industry, an abundance of supplement products of dubious value, content, and quality are now available around the world. Many supplement products contain substances that are prohibited in sport or that have been associated with significant morbidity and mortality. For athletes, lack of knowledge or misinformation has been established despite numerous sources of information being available, and the reasons for, and implications of, unsupervised and unrestricted supplement use require further attention. In addition to the necessity of an appropriate regulation of dietary supplements, nutritional education and scientifically sound guidance for athletes is required. Intervention and prevention efforts should be particularly targeted to adolescents.