Most undisclosed substances found in the tested products were themselves experimental. (iStock)
Many bodybuilding products sold online are mislabeled and contain unapproved drugs and other ingredients that may not be safe, a new study suggests.
Researchers tested 44 products they bought online that were marketed as nonsteroidal selective androgen receptor modulators (SARMs), which mimic the effect of testosterone and help build muscle.
Overall, only about half of these items actually contained SARMs, the study found. One in four products contained ingredients that weren't on the label, including potentially dangerous drugs, and 59 percent had more or less than the advertised amounts of certain ingredients.
"Our findings show that people should be extremely careful about using these unapproved drugs purchased over the internet not only because these drugs can have harmful effects on their health, but also because the labels cannot be trusted and many products may contain other chemicals not listed on the label whose safety is unknown," said study co-author Dr. Shalender Bhasin of Harvard Medical School Brigham and Women's Hospital in Boston.
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Anabolic steroids are among the most frequently abused appearance- and performance-enhancing drugs, researchers note online November 28 in JAMA. Use of these drugs was once mostly limited to athletes, but they've gained in popularity among men seeking to build muscle and appear more fit.
SARMs are designed to have effects similar to steroids, and several companies are developing SARMs as potential treatment for functional limitations associated with aging and muscle-wasting disorders.
The U.S. Food and Drug Administration hasn't approved any SARMs to treat these medical problems. These unapproved drugs are marketed as dietary supplements even though they haven't been reviewed for safety or effectiveness, the FDA has warned.
Consumers shouldn't use SARMs in bodybuilding products because they can have life-threatening side effects such as heart attacks, strokes and severe liver damage, the FDA has warned.
SARMS, like anabolic steroids, are among the substances athletes aren't allowed to use under rules outlined by the World Anti-Doping Agency.
For the study, researchers searched online for suppliers selling SARMs and bought all of the items they found that were in stock and possible to purchase.
Then, the study team had all of the products they bought tested using protocols followed by the World Anti-Doping Agency.
Some products were found to contain a drug that increases growth hormone and other substances that are also banned by that agency, the study found. Four products were found to contain the breast cancer drug tamoxifen.
Most undisclosed substances found in the tested products were themselves experimental. Some of the compounds - Ostarine, Andarine, LGD-4033 and ibutamoren - have been tested in humans even though they have not yet won approval by the FDA.
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Development of another compound found in tested products, GW-501516, was halted because of safety concerns.
Another compound discovered in the products, SR9009, has been through some preliminary clinical trials but hasn't yet been tested in humans.
"But people do spend millions of dollars on unregulated drugs every day - and at their peril," said Dr. Richard Auchus, author of an accompanying editorial and a researcher at the University of Michigan in Ann Arbor.
Vitamin D and calcium are the only supplements people should buy, and even then consumers should only shop from legitimate suppliers like the website for a drugstore chain, Auchus advised.
That's because the current study highlights problems with supplements that go beyond just SARMs, which may lure a subset of the bodybuilding community with a distrust of medical professionals and a penchant for risk-taking behavior, Anchus said by email.
"This is one of many warnings about such supplements that scam and endanger the public," Auchus added.