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 first but not food only' approach remains central 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 inadvertent antidoping rule violations (ADRVs). Evidence Acquisition: This structured narrative review searched PubMed and Scopus for literature published between January 2000 and December 2025. Evidence from primary studies, randomised controlled trials, systematic reviews, meta-analyses, mechanistic studies, contamination analyses, behavioural research, consensus statements and official guidance documents from major sports and antidoping organisations was critically evaluated and synthesised. A PRISMA-style literature identification and evidence-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-specific strength of recommendation reported separately. Results: Evidence supporting supplementation varies substantially across categories. Creatine and caffeine have the most consistent evidence for selected performance outcomes, whereas beta-alanine, dietary nitrate and sodium bicarbonate show context-specific benefits. Iron and vitamin D have clearer clinical indications when deficiency is present, but limited evidence supports routine use in replete athletes. Many recovery- or health-oriented supplements rely on smaller, heterogeneous studies or indirect outcomes. Contamination risk is also heterogeneous and is highest for multi-ingredient products, preworkout supplements, weight-loss products, muscle-building products, 'testosterone boosters', selective androgen receptor modulators (SARMs) and other substances positioned as supplements despite pharmacological or prohibited profiles. Effective risk reduction requires individual nutritional assessment, evidence-based selection, third-party certification, product verification, education of athletes and Athlete Support Personnel, and systematic documentation. Conclusions: Supplement use in athletes should be considered a controlled, individualised and documented intervention rather than routine practice. The proposed framework integrates efficacy, evidence quality, mechanisms of action, contamination pathways, behavioural determinants, strict liability and antidoping risk to support safer supplementation decisions. Protecting athlete health and the integrity of clean sport requires a shift from performance-driven to risk-aware supplementation.Strength-of-Recommendation Taxonomy (SORT): Overall framework: B/C, based on consensus statements, position stands, limited controlled studies and expert-informed synthesis. Supplement-specific ratings are provided in Table 2.