That powdered herbal pill you’ve popped may not contain what you think. According to a new DNA-based study of a few dozen products from several herbal supplement companies, many supplements are packed with inert fillers that are not listed on the labels, including wheat, rice, and soybeans—and a few are apparently devoid of the very herbs they advertise.
The findings draw attention to a $5.6 billion U.S. market in herbal remedies that some critics say is too lightly regulated. Although many Americans regularly use supplements ranging from echinacea to saw palmetto to ginkgo—hoping to treat colds, boost prostate health, and preserve memory—some sellers have exaggerated the health benefits of certain products, or failed to disclose potentially harmful ingredients on the label.
The study, conducted by researchers at the University of Guelph in Canada and Bharathiar University in India, used “DNA barcoding” to determine which plant species were present in 44 herbal supplements selected from 12 companies. The tests indicated nearly 60 percent of the supplements contained at least one plant ingredient not listed on the label. Although such fillers might be used to prevent the ingredients from sticking together, some, such as wheat, could pose a hazard in significant amounts for gluten-intolerant people.
In one-third of the supplements tested, the main advertised ingredient was nowhere to be found: Instead, the product contained other substitute plant ingredients. Only 2 of the 12 companies tested had products whose ingredients consistently matched those listed on the labels. One supplement labeled as St. John’s wort, an herb used as a remedy for depression or anxiety, contained only rice, according to the DNA tests. Some supplements were contaminated with feverfew, a bushy plant with daisy-like flowers that is sometimes used to treat fevers and headaches, but can provoke an allergic reaction in some people and increase the risk of miscarriage in pregnant women. (The researchers, publishing in BMC Medicine, did not release the names of the supplement manufacturers.)
Tod Cooperman, the president of ConsumerLab.com, which provides third-party testing of nutrition products, told me the study results should “shake people up.” His company has tested over 3,500 nutrition products since 1999, checking for quality potency or contamination with potentially toxic substances, like pesticides: “Based on our most recent tests of herbal supplements, 43 percent have failed our tests.”
ConsumerLab.com is preparing to release a report about the weight loss supplement Garcinia cambogia. Out of 11 products the company purchased, Cooperman said, six contained less than half the amount claimed on the package.
The FDA allows companies to make and sell dietary supplements without prior approval, as long as they follow industry quality standards to prevent contamination with toxins. The agency monitors products on sale found to be harmful or falsely labeled. Companies that make supplements are not allowed to claim their products will prevent or cure any specific disease. They can, however, claim that a product like coenzyme Q10 can “help maintain heart health,” for example.
A critic of the new study, Stefan Gafner, the chief science officer at the American Botanical Council, claimed to The New York Times the DNA barcoding technique was flawed because it might not identify plant matter that had been highly processed.
“I don’t think it’s as bad as it looks according to this study,” Gafner said, while admitting there were quality control problems in the herbal industry.
Steven Newmaster, the paper’s lead author, emphasized the supplements his team tested involved only powders and pills—not extracts that DNA testing might miss. DNA from the substitute plants contaminating the products seemed to show up readily enough.
However, Cooperman noted that most herbal products sold in the U.S. today are extracts, rather than pills, so other types of testing would be necessary to ensure their quality.
A report by the Government Accountability Office in 2010 found that almost all dietary supplements researchers tested contained trace amounts of heavy metals like lead and mercury, in amounts well below the safety threshold. Others contained pesticides, or were labeled with illegal claims that they could treat cancer or Alzheimer’s.
Other studies have found herbal supplements can have harmful effects when mixed with prescription drugs. St. John’s wort, for example, is known to interact with 147 medications.