Adolescent alcohol use among boys was prospectively associated with use of legal performance-enhancing substances in young adulthood, based on prospective cohort data from more than 12,000 individuals, wrote Kyle T. Ganson, PhD, MSW, of the University of Toronto, and colleagues.
In addition, legal use of performance-enhancing substances (PES) among young men was associated with increased risk of alcohol use problems.
Although previous studies have shown a range of adverse effects associated with the use of anabolic-androgenic steroid derivatives (defined as illegal PES), the possible adverse effects of legal PES (defined in this report as protein powders, creatine monohydrate, dehydroepiandrostenedione, and amino acids) have not been well studied, the researchers wrote.
In a study published in, the researchers reviewed data from 12,133 young adults aged 18-26 years who were part of the National Longitudinal Study of Adolescent to Adult Health from 1994 to 2008.
Overall, 16% of young men and 1% of young women reported using legal PES in the past year. Among men, legal PES use was prospectively associated with increased risk of a range of alcohol-related problem behaviors including binge drinking (adjusted odds ratio, 1.35), injurious and risky behaviors (aOR, 1.78), legal problems (aOR, 1.52), reduced activities and socializing (aOR, 1.91), and problems with emotional or physical health (aOR, 1.44).
Legal PES use among young adult women was associated with an increased risk of emotional or physical health problems (aOR, 3.00).
Between adolescence and young adulthood (an average of 7 years’ follow-up), alcohol use was prospectively associated with legal PES use in young men (OR, 1.39), but neither cigarette smoking nor marijuana use in adolescence was associated with later use of legal PES. Among young women, no type of adolescent substance use was prospectively associated with later use of legal PES.
“To date, legal PES have not been largely considered as part of the spectrum of substances used among adolescents, have not been subject to the same regulatory scrutiny as other substances known to be linked to subsequent substance use and are freely available over the counter to adolescents,” Dr. Ganson and associates noted.
“Clearly, the robust reciprocal temporal relationship between substance use and legal PES suggests that each may serve as a gateway for the other,” they wrote.
The study findings were limited by several factors including the inability to identify outcomes associated with variable PES components, incomplete data collection on several drinking-related risk behaviors, and inability to analyze prospective use of illegal or other substances associated with use of legal PES, the researchers wrote.
However, “these results provide further evidence in support of the gateway theory and prospective health risk behaviors associated with legal PES and substance use,” they wrote.
The data may inform policy on the additional regulation of legal PES use in minors. In the meantime, “it is important for medical providers and clinicians to assess problematic alcohol use and drinking-related risk behaviors among young adult men who have previously used legal PES,” Dr. Ganson and associates concluded.