Dietary Supplement Use and Doping Attitudes: A Cross-Sectional Survey

Background: The incremental model of doping behavior (IMDB) posits that doping develops over time through the habit of using performance enhancers such as dietary supplements. We investigated the association between dietary supplement use and beliefs and doping attitudes among Norwegian sportspersons. Methods: A total of 1441 subjects (females: 44%; age 31.3 ± 11.6 years) responded to an online questionnaire including measures of dietary supplement use and beliefs, performance enhancement attitude (PEAS), and a doping likelihood vignette. Data were analyzed using descriptive statistics, correlations, and multiple regression analysis. Results: 58% used dietary supplements. Dietary supplement beliefs were positively correlated with doping attitudes (r = 0.27 (PEAS) and r = 0.16 (vignette), p < 0.001). Among non-competitive respondents, younger respondents were more likely to endorse supplement use (r = −0.08, p = 0.073 vs. r = −0.30, p < 0.001) and doping use (r = −0.17, p < 0.001 and r = −0.21, p < 0.001). Males endorsed supplement use (Welch’s t tests > 5.19, p < 0.001) and doping (Welch’s t tests > 4.08, p < 0.001) more than females. Norwegian sportspersons are generally ambivalent about dietary supplements but opposed to doping practices in sport. Results of multiple regression analysis indicated that younger, male, non-competitive, and supplement-endorsing participants were more likely to endorse doping likelihood. However, these differences were small, and participants were generally against doping. Conclusions: The associations between dietary supplement use and beliefs and doping attitudes are weak but compatible with the IMDB. The differences between groups are small; however, focusing on beliefs about dietary supplements in young, male, non-competitive persons may improve the effectiveness of anti-doping interventions.