The supplements, which are being marketed to sports people looking to build lean muscle while reducing body fat and enhancing endurance, was revealed by a team led by Dr Alison Heather, a physiology professor at the University of Otago in Dunedin.
"The point is that you can't judge a book by its cover,” Heather said. ”The nutritional supplement label may not disclose all ingredients, and sometimes these additions are not declared on the product label.
“Athletes risk testing positive for a banned substance and the general public risks being inadvertently exposed to androgens, which have recognised health risks.”
The presence of androgens—usually steroid hormones that control the development of male characteristics by binding to androgen receptors—in the supplements is a cause for concern, especially as most of the tested products did not declare their addition.
Heather said her team must now investigate further to identify which androgens appear in the supplements to better understand the implications for health and sports doping,.
The worldwide dietary supplement market is worth an estimated US$142.1bn, and by 2017 it is expected to reach almost $205bn. Most androgen-containing supplements state their contents on the label.
Yet there have been many reports of unlabelled androgen-containing supplements, with some companies covertly adding androgens to their nutritional supplements to better satisfy their advertised claims.
More stringent testing
To investigate the availability of unlisted androgens in over-the-counter nutritional sports supplements, Heather and her team bought 79 random nutritional supplements from stores in Sydney. These included protein powders, amino acids, creatines, fat metabolisers, so-called testosterone-boosters, carbohydrates and stimulant/nitric oxide pre-workout supplements.
Of the 74 samples they tested by bioassay, six were androgen-positive even though they did not list this on the label. One other tested positive, but was listed an androgen on the label.
Although only 10% of the tested supplements proved positive for androgens, Heather is still concerned that some players in the nutritional sports supplement industry lack transparency in revealing all the ingredients in their products.
To counter this, she recommended more stringent legislation to make the public fully aware of what they are putting into their bodies.