By Pat Anson, PNN Editor

Hundreds of dietary supplements – including some marketed to relieve joint and muscle pain – are tainted with pharmaceutical drugs, according to a new study published in JAMA Network Open.  

Researchers with the California Department of Public Health looked at 746 supplements that the Food and Drug Administration found to be adulterated from 2007 to 2016. About half of the supplements remained on the market, even after the FDA found they contained potentially harmful drugs.

"The FDA didn't even bother to recall more than half of the potentially hazardous supplements," Pieter Cohen, MD, a Harvard Medical School professor told NPR. "How could it be that our premier public health agency spends the time and money to detect these hidden ingredients and then doesn't take the next obvious step, which is to ensure that they are removed from the marketplace?"

Over half of American adults take dietary supplements that contain minerals, vitamins, herbs, fish oil and other “natural” substances.  Most of the adulterated supplements were marketed for sexual enhancement, weight loss or muscle building.

Of the 14 supplements that were promoted as treatments for arthritis, muscle and joint pain, osteoporosis or other painful conditions, half contained diclofenac, a nonsteroidal anti-inflammatory drug (NSAID) and five contained dexamethasone, a steroid used to treat inflammation.

One supplement promoted as a treatment for arthritis – Pro ArthMax -- was found to contain four different NSAIDs, as well as a muscle relaxant and a non-narcotic pain reliever that was never approved for use in the United States. The manufacturer of Pro ArthMax voluntarily recalled the supplement in 2014 after being warned by the FDA.   

Cohen chided the agency for relying on voluntary recalls to get tainted supplements off the market and accused the FDA of “dereliction of duty” in a JAMA commentary. He called on Congress to change the federal law that exempts the $35 billion dollar supplement industry from pre-market safety and clinical studies that are required for pharmaceutical drugs.   

“More than FDA action will be required to ensure that all adulterated supplements are effectively and swiftly removed from the market,” Cohen wrote. “The process that the FDA is required to follow to remove supplements from the marketplace (is) cumbersome and time-consuming; nevertheless, the agency’s failure to aggressively use all available tools to remove pharmaceutically adulterated supplements from commerce leaves consumers’ health at risk.”

Dietary supplements that are tainted with hidden drugs may interact with other medications and raise the risk of adverse events, particularly when consumers already may be using NSAID-containing products.