[Fraud in nutritional supplements for athletes: a narrative review].

The use of nutritional supplements (NSs) is a widespread practice in both professional and amateur athletes. Their choice must be based on criteria of safety, legality, and effectiveness. There are several risks that some of these products can trigger, this being a reason for fraud to the consumer. By way of example, the presence of a legal substance in doses higher than its recommendation may cause unwanted side effects; on the other hand, its presence in quantities lower than necessary (effective threshold) may not have the effect expected or announced by the product. Therefore, the objective of this review was to describe the existence of fraud in relation to nutritional labeling and/or to the content of NSs intended for athletes. A narrative review was conducted through PubMed in which 16 studies met the inclusion criteria. The results show that nutritional labeling differs from the actual amounts of ingredients. This type of fraud has been found in protein powder supplements, pre-workout mixtures, creatine, and beverages containing vitamins and minerals, among others. Fraud due to errors in the labeling by omission of substances present in the product or by errors in the analysis or declaration of quantities, is high. This lack of transparency in the actual composition of labels can contribute to sports performance and/or health problems in the athlete. Therefore, an improvement of the legislation on NS is necessary to ensure their safety, effectiveness, and legality.