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Bodybuilding supplement may contain breast cancer drug and added risks

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Reported by the Huffington Post UK on Feb. 15, evidence of a drug used to treat breast cancer was found in samples of a dietary supplement marketed to male athletes such as bodybuilders who use anabolic steroids.

Between 2011 and early 2012, a team of Liverpool John Moores University researchers purchased four samples of Esto Suppress, and found Tamoxifen present in three of the four samples analyzed. Used as a type of hormone therapy in the treatment of breast cancer, Tamoxifen blocks estrogen activity to stop or slow the growth of breast cancer cells. According to the National Cancer Institute, approximately 70 percent of breast cancers are ‘estrogen sensitive’ where in the estrogen hormone receptors become activated when estrogen binds to them, stimulating cancer tumor growth

Esto Supress is promoted as a “potent anti-estrogenic compound” recommended for bodybuilders as a means to eliminate the estrogen that develops in response to the large testosterone boost from heavy anabolic steroid use.

Tamoxifen is one of the selective estrogen receptor modulators (SERMs) approved by the FDA and used for more than 30 years in breast cancer treatment; according to the Liverpool researchers male bodybuilders have taken Tamoxifen for more than 30 years to prevent and treat enlarged breast tissue (gynecomastia), a common side-effect from repeated anabolic steroid cycles.

Yet even with informed use, Tamoxifen has its risks: from mood swings and depression to blood clots, stroke, cataracts and even other forms of cancers. In a letter posted to the BMJ on Feb. 14, the Liverpool researchers warn of the dangers of such “pharmacologically active substances” that are present in a “growing number of off-the-shelf “food,” “herbal,” or “dietary” “supplements”—aimed at gym goers” who are unaware they are taking such substances; in the case of Esto Supress, the Tamoxifin is listed by the chemical name only.

It is not known whether the Esto Suppress currently being sold still contains tamoxifen, but the researchers’ stress that it is important that healthcare professionals ask their patients about their use of “supplements” and report suspected adverse reactions

Bodybuilders Unaware Of Consuming Supplements That May Contain Breast Cancer Drug, Experts Warn, Feb. 14, PA/The Huffington Post UK

Is the breast cancer drug tamoxifen being sold as a bodybuilding dietary supplement?, Feb. 13, BMJ 2014; 348:g1476,