Minute levels of banned substances in some dietary supplements are leaving athletes susceptible to failed drugs tests according to Loughborough University Professor of Sport and Exercise Nutrition Ron Maughan.
Professor Maughan, who chairs the Sports Nutrition Group of the International Olympic Committee Medical Commission, has warned of the dangers of commercially available supplements which could turn athletes into unwitting drugs cheats.
He said: "It is now well established that many dietary supplements contain compounds that can cause an athlete to fail a doping test. In some cases the presence of these compounds is not declared on the product label.
"For some prohibited substances, the amount that will trigger a positive test is vanishingly small and may not be detected by routine analysis of the supplement."
Professor Maughan has raised particular concerns about the presence of the steroid nandrolone (and its metabolic precursors) which are banned by the World Anti-Doping Agency (WADA).
Maughan and his team investigated athlete responses to trace amounts of a nandrolone precursor (19-norandrostenedione) where subjects ingested either water or a commercial sports bar contaminated with minute levels of the banned substance.
Despite contamination levels 1,000 times lower than concentrations typically scanned for during supplement manufacture, volunteers' samples still registered a positive doping result for nandrolone.
Professor Maughan added:
"The potential for such low levels of contamination in a sports supplement to result in adverse test results raises significant concerns for the manufacture of dietary supplements intended for consumption by athletes liable to regular doping tests.
"It presents a serious dilemma for sports supplement manufacturers, athletes, and those responsible for the welfare of athletes."
This week Professor Maughan is presenting at a Science Media Centre briefing on the science of anti-doping testing and at the inaugural event of the Royal Society of Chemistry lecture series - "Athletes, Chemists, Law and Sport - Who's Really Winning?".