Are Dietary Supplements, Harmful or Good for Athletes?

Athletes are bombarded with nutritional/dietary supplements (NSs/DSs) that promise to improve health, function, and performance. Many of these claims, however, are based on little evidence, and the efficacy and safety of many products are debatable. A review of doping, risk factors, protective factors, performance enhancement, sports performance, dietary supplements, nutritional supplements (NSs), and health consequences was completed using PubMed, Google Scholar, Web of Science, and Science Direct. The inclusion criteria were studies published up until June 2021, which analyzed the content of nutritional/dietary substances and their influence on sports performance. Seventy-three review articles were included in this review. In summary, supplementation will always be a part of athletes’ careers due to its perception of ergogenic capabilities, and there is evidence of some dietary nutritional supplements DSs/NSs substances supporting performance enhancement and recovery. However, there is data that due to real harm and unethical manufacturing and marketing practices, some products may contain unwanted/illegal substances. Athletes should be aware of the risk of being tested positive due to contamination of NSs/DSs with a World Anti-Doping Agency (WADA)-banned substance. Athletes and coaches should stick only to supplements that show strong research evidence supporting sports performance and safety use.