Reducing the Risk of Unintentional Doping From Supplements: A Practical Guide for Athletes and Support Teams

Context: Dietary supplements are widely used across all levels of sport. While the ‘food frst but not food only’ approach remainscentral to sports nutrition, selected supplements may support performance, recovery or health when used appropriately. However,variable regulation, product contamination, mislabelling and inappropriate decision-making may expose athletes to inadvertentantidoping rule violations (ADRVs).Evidence Acquisition: This structured narrative review searched PubMed and Scopus for literature published between January2000 and December 2025. Evidence from primary studies, randomised controlled trials, systematic reviews, meta-analyses,mechanistic studies, contamination analyses, behavioural research, consensus statements and ofcial guidance documents frommajor sports and antidoping organisations was critically evaluated and synthesised. A PRISMA-style literature identifcation andevidence-selection diagram is provided as Supporting Table S1; the review was not designed as a systematic review or meta-analysis.Study Design: Narrative clinical review.Level of Evidence: Level V for the overall narrative framework, with supplement-specifc strength of recommendation reportedseparately.Results: Evidence supporting supplementation varies substantially across categories. Creatine and cafeine have the mostconsistent evidence for selected performance outcomes, whereas beta-alanine, dietary nitrate and sodium bicarbonate showcontext-specifc benefts. Iron and vitamin D have clearer clinical indications when defciency is present, but limited evidencesupports routine use in replete athletes. Many recovery- or health-oriented supplements rely on smaller, heterogeneous studies orindirect outcomes. Contamination risk is also heterogeneous and is highest for multi-ingredient products, preworkout supple-ments, weight-loss products, muscle-building products, ‘testosterone boosters’, selective androgen receptor modulators (SARMs)and other substances positioned as supplements despite pharmacological or prohibited profles. Efective risk reduction requires