Martínez-Sanz et al. 2017, doping substances in dietary supplements (review)

Review in Nutrients, “Intended or Unintended Doping?”, examining the presence of WADA-prohibited substances in sports dietary supplements. From 446 screened records it reviewed 23 studies that analysed supplements for banned substances. Reported contamination rates with prohibited substances ranged between 12% and 58% across studies, with undeclared substances including both prohormones and steroids and a range of stimulants. The authors concluded that unintentional doping through supplements is a real and significant risk and that athletes should verify a product’s safety and manufacturer guarantees before use. The wide 12–58% range reflects heterogeneous, often high-risk product samples rather than a representative population, so it should be read as a spread across studies, not a single prevalence figure for all supplements.