Athletes are using increasing amounts of dietary supplements to help boost their performance, but many of the products they use are contaminated by substances that could result in positive tests for anabolic steroids, according to the International Olympic Committee.
A report in the Financial Times cites an IOC study which shows that consumers of such dietary supplements, most of which are easily available over the counter, may unwittingly be taking pro-hormones of nandrolone and testosterone, substances banned by the IOC.
Dr Patrick Schamasch, IOC medical director, told the paper: "Many of these products are also used by teenagers. It means teenagers may be taking hormones without knowing it. This makes it also a public health issue."
The study found that 14.8 per cent of 634 nutritional supplements tested contained non-labelled substances that could lead to a positive doping test.
Dr Schamasch said the majority of contaminated supplements contained pro-hormones of nandrolone, testosterone or both. Nandrolone has been linked to liver cancer and loss of fertility.
Nandrolone has been the cause of several high-profile doping cases in recent years, with everyone from Olympic athletes to popular soccer players found guilty of using the product.
Dr Schamasch told the paper that most contaminated products were made by small companies, claiming that they may not have cleaned their equipment thoroughly. "Probably 90-95 per cent of these substances are not contaminated deliberately," he said.
A high proportion of contaminated products originated in the US where regulation was less strict than in Europe, prompting the IOC to increase pressure on the US government to tighten regulation in the sector.