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Herb Adulteration: What’s Really In That Supplement?

As early as 2006, I used to be able to write monthly about US FDA warnings on erectile dysfunction supplements being found adulterated with prescription drugs such as sildenafil, the phosphodiesterase-5 inhibitor found in Viagra. These adulteration episodes raised the question of how many anecdotal reports of herbal products “working” had to do with them containing approved medicines.

So common was this practice that FDA created a site in 2008 that was dedicated to this problem: Hidden Risks of Erectile Dysfunction “Treatments” Sold Online. Indeed, these products were more commonly encountered from online retailers and not in health food stores. Other similar practices include bodybuilding supplement being spiked with anabolic steroids and weight loss supplements being adulterated with sibutramine (formerly Meridia), an anorectant removed from the market last year after showing increased incidence of heart attacks and stroke in patients with preexisting cardiovascular disease.

The herbal industry, led by the American Herbal Products Association (AHPA), aimed to clean up this problem and launched an initiative called, KeepSupplementsClean.org. Spurred by an FDA letter to the industry on 15 December 2010 of increased scrutiny on the adulteration problem, AHPA actually encouraged FDA to root out manufacturers who adulterated their products or failed to qualify suppliers of their raw materials.

AHPA has publicly expressed its support for FDA actions against marketers of products that masquerade as dietary supplements but contain illegal ingredients. AHPA encourages FDA to use its regulatory authority to hold accountable those who violate the law and jeopardize the public confidence, including all legal means to enforce the law.

The initiative seems to have been effective. This week, the independent testing organization ConsumerLab.com reported that testing of 11 “sexual enhancement” products revealed no adulteration with prescription drugs. On the other hand, the organization showed that, “[f]our products contained less of a key ingredient than claimed on the label, one product was contaminated with an unacceptable level of lead, and two products lacked FDA-required information on their labeling.”

Economically-Motivated Adulteration

This week also saw increased attention on another problem: herbal supplements containing less-expensive plant materials, some of which can cause liver damage. A US Department of Agriculture group has published an analytical method to detect adulteration of Scutellaria lateriflora L. (American skullcap) with two species of germander, a plant well known to contain compounds bioactivated by cytochrome P450 to reactive chemicals that damage the liver. The group of Vanderbilt University biochemist Larry Marnett showed in an elegant 2007 Chemical Research in Toxicology paper how the germander compound teucrin A is activated and identified key proteins in the liver that are chemically attacked by the reactive metabolite.

Skullcap supplements are normally taken to relieve anxiety and do indeed contain flavone compounds that bind to the benzodiazepine site on GABAA receptors like some prescription drugs. However, the herb hasn’t fared well in clinical trials for anti-anxiety activity.

Well, how’s this for increasing anxiety: In the current USDA study, 13 Scutellaria lateriflora products were tested using the new method and four were found to contain teucrin A, indicating that the products contained germander.

But this is apparently old news. In a NutraIngredients USA article that discussed the paper’s findings, American Botanical Council founder and Executive Director Mark Blumenthal called the finding, “disappointing, but by no means surprising,” noting that,

Many experts in the herb community have known about this misidentification for many years, he said. “ABC published an article by botanist Steven Foster about this problem in HerbalGram in the fall of 1985! Foster cited this problem as having been around for decades.

Indeed, one can find on the ABC website a nice monograph by Gayle Engles on the history of skullcap use and the cases of human hepatotoxicity from the 1980s.

The use of cheaper materials in drug and supplement products came to light with melamine used to artificially boost apparent protein content in pet food and infant formula products in China. In 2009, the Council for Responsible Nutrition released a statement on the problem of economically-motivated adulteration in the supplement industry. While the new Good Manufacturing Practice guidelines for the industry were intended to address this issue, the current USDA analytical paper tells us that more stringent enforcement of the rules is necessary.

Until then, be careful when taking herbs for anxiety. Because that’s exactly what you might get.

*This blog post was originally published at Science-Based Medicine*


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