“Since the 2000s, a growing number of off-the-shelf ‘food,’ ‘herbal,’ or ‘dietary’ ‘supplements’—aimed at gym goers and people wanting to lose weight or enhance their sex lives—have contained pharmacologically active substances,” the authors wrote. “Most users will be unaware that they are taking these substances.”
The amount of tamoxifen varied by sample, with one sample containing 3.8 mg per pill. The suggested dose of Esto Suppress is two pills per day; when the drug is prescribed for early-stage breast cancer, patients typically take 20 mg a day. The researchers noted, however, that their samples were purchased two years ago, and it is not known whether the supplement still contains tamoxifen.
“This research highlights the need for consumers to be aware when choosing their sports supplements,” a spokesman for the Medicines and Healthcare Products Regulatory Agency (MHRA) told HuffPost Lifestyle. “These products may claim to increase performance but can contain powerful ingredients which can have serious side-effects.”