Refined Analysis of a Cross-Sectional Doping Survey Among Recreational Triathletes: Support for the Nutritional Supplement Gateway Hypothesis

Introduction: The current literature provides no consensus that nutritional supplements (NS) may provide a gateway to doping. In particular, studies in recreational athletes are lacking. Within a previous cross-sectional empirical study, our group provided first evidence that the use of NS may provide a gateway for the use of doping substances in recreational triathletes. For the present paper, we refine the analysis of the triathletes’ survey in order to provide evidence for a NS gateway hypothesis in recreational athletes. Methods: A self-report, paper-and-pencil questionnaire was distributed to a sample of 2,997 competitive ironman and half-ironman (n = 1,076; 36.1%) triathletes. The randomized response technique (RRT) was used to assess the 12-month prevalence estimate for the use of doping substances. The prevalence for the use of NS was assessed by using direct questioning. Two-tailed (α = 0.05) large-sample z-tests were performed to assess whether the estimated prevalence for the use of doping substances differs significantly between users and nonusers of NS. Results: The 12-month prevalence estimate for the use of doping substances is significantly higher in athletes who report using NS (20.6%) compared to those who do not (11.4%; z = 2.595, p = 0.0097). Conclusion: The present results are consistent with the hypothesis that the use of NS provides a gateway to the use of doping substances. Therefore, doping prevention concepts should not primarily focus on preventing the use of doping substances per se, but should start one step earlier, namely by the use of NS.