Background
Nutritional sports supplements are often marketed to athletes to help build lean muscle tissue, reduce body fat and enhance endurance. The lack of Good Manufacturing Practice and regulation in the production and sale of nutritional supplements has often led to the covert fortifying of these supplements with anabolic steroids to better achieve the claimed benefits of the nutritional sports supplement. These additions are not declared on the product label and may have potential health risks to consumers if taken unknowingly and for an extended length of time. Moreover, consumption of these supplements may elicit a positive doping test for a professional athlete.

Aim
The aim of the study is to screen a range of nutritional sports supplements from the Australian market for the presence of androgenic and progestogenic molecules using in vitro yeast cell-based bioassays.

Methods
Forty nutritional sports supplements were randomly purchased from Sydney-based stores and underwent a solid-phase extraction method with a C18 column to obtain a steroidal extract that was subsequently tested for androgenic and progestogenic bioactivity. The bioassay used is a Saccharomyces cerevisiae based assay co-transformed with an androgen receptor or progesterone receptor expression plasmid a response element and β-galactosidase reporter vector used to measure receptor activity.

Results
Of the 40 supplements tested, 4 supplements were positive for androgenic bioactivity with relative bioactivity of 10, 5, 2.1, and 1.5 compared to testosterone. Furthermore, 4 different supplements displayed weak progestogenic activity with relative bioactivities of 0.37, 0.38, 0.42 and 0.66 compared with progesterone. Additionally, one supplement did not display any activity but demonstrated strong anti-progestogenic bioactivity, lowering the bioactivity of progesterone by 62%.

Conclusion
Using a yeast-based androgen and progestogen bioassay, 9 sports nutritional supplements from the Australian market displayed androgenic and (anti)progestogenic activity, with only 1 of these supplements declaring the presence of a hormone.