Supplement users were 2.74 times more likely to report doping

Dietary supplements are near-universal in competitive sport, and for a decade researchers have debated whether using them nudges athletes towards prohibited performance-enhancing substances — a kind of gateway question with real consequences for anti-doping policy. Sport organisations need to know whether supplement use genuinely tracks with doping before they build education programmes around it. This systematic review and meta-analysis set out to quantify the relationship: first, comparing the prevalence of doping between supplement users and non-users, and second, testing whether supplement use relates to the social-cognitive factors, such as intentions and attitudes, that predict doping behaviour.

The reviewers searched EMBASE, MEDLINE, PsychINFO, CINAHL and SPORTDiscus from database creation to May 2022 for studies that sampled athletes and measured both dietary supplement use and doping. Twenty-six cross-sectional studies met the criteria, together involving 13,296 athletes. Risk of bias was assessed using the JBI Critical Appraisal Checklist for cross-sectional studies and the STROBE checklist, and random-effects models were used to pool prevalence rates and the correlations between supplement use and doping-related intentions and attitudes.

Doping was 2.74 times more prevalent among dietary supplement users than non-users, with a pooled prevalence of 14.7% for users against 6.7% for non-users. Supplement users also reported stronger doping intentions (r=0.26) and more favourable doping attitudes (r=0.21). Preliminary evidence suggested a protective pattern too: supplement users were less likely to dope if they were more task oriented and had a stronger sense of morality. The authors note that a large proportion of athletes use supplements without doping, and that inconsistent measurement of both supplement use and doping across studies limits the findings.

This is the first pooled estimate of a relationship that individual studies have reported for years, and it puts a number on it. But because every included study was cross-sectional, it cannot establish direction: whether supplement use precedes doping, whether the same attitudes drive both, or something else entirely. The authors argue anti-doping education should address supplement use directly, and they flag an important open question — what protects the majority of supplement-using athletes who never dope. Task orientation and moral values are early candidates, but that evidence is preliminary.

If you compete in any tested sport, this is context worth having: supplement use and doping cluster together statistically, which is one reason anti-doping bodies pay attention to supplement culture. It does not mean taking protein powder or creatine sets anyone on a path to prohibited substances — most supplement-using athletes in these studies did not dope. The finding is better read as a signal about attitudes and environments than about the supplements themselves, and the researchers themselves call for education offering safer strategies rather than blanket alarm.