Systematic review of undeclared prohibited substances and pharmacological adulterants in dietary supplements: prevalence, detection, and risks in sport

Introduction: The proliferation of dietary supplement use among athletes has heightened concerns over inadvertent doping due to contamination with substances prohibited by the World Anti-Doping Agency (WADA) and other undeclared pharmacological adulterants. This systematic review synthesizes empirical evidence on the prevalence, detection, and risks associated with sport supplement contamination. The review framework encompassed both explicitly prohibited doping agents and potent metabolic adulterants that pose significant regulatory and health risks. Methods: Following PRISMA guidelines, 12,031 records were initially identified across Scopus, Web of Science, and SPORTDiscus, of which 44 studies met the inclusion criteria. Results: Findings indicate that approximately 9-15% of commercially available supplements tested in empirical studies were contaminated with prohibited substances and unapproved pharmacological agents, predominantly stimulants and anabolic agents. Contamination was most frequently identified in pre-workout, weight-loss, and muscle-building products. Liquid Chromatography-Mass Spectrometry (LC-MS) emerged as the most widely used analytical method, followed by Gas Chromatography-Mass Spectrometry (GC-MS) and hybrid spectroscopic techniques, enabling high-sensitivity detection across diverse substance classes, including structural analogs and emerging metabolic markers.The findings highlight a critical gap between product labeling and actual chemical composition, posing a persistent threat to athlete integrity and public health. Discussion: This review stresses the need for more stringent international manufacturing standards, expanded analytical screening protocols that account for emerging structural analogs, and enhanced athlete education to mitigate the risk of unintentional doping.