Herbal supplements are a $5 billion industry. But the FDA does not regulate supplements the same way they do prescription drugs, which means many herbal supplements are not what they seem. Creative Commons

There’s the age-old adage that things aren’t always what they seem. Unfortunately, even in the age of regulation, that proverb still holds true for consumers of dietary supplements. According to a new study, most of the herbal supplements we buy that promise, among other things, to boost memory, enhance our mood or fight off colds are, for the most part, totally bogus. The New York Times reported that one-third of all herbal supplements tested in the study contained nothing more than “powdered rice and weeds.”

Researchers in Canada reviewed 44 different herbal supplements, ranging from things like Ginkgo biloba, often thought to treat memory disorders, to St. John’s wort, which purportedly treats mild depression. Using a sophisticated method of DNA barcoding, a technique of genetic “fingerprinting” developed about a decade ago, scientists found that one-third of them were complete substitutions. Many of them simply contained fillers like wheat, rice and soybean.

“This suggests that the problems are widespread and that quality control for many companies, whether through ignorance, incompetence or dishonesty, is unacceptable,” David Schardt, a senior nutritionist at the Center for Science in the Public Interest, a safety and nutrition advocacy group, told The New York Times. “Given these results, it’s hard to recommend any herbal supplements to consumers.”

Other herbal supplements were discovered to be adulterated with ingredients not listed on the label. Ginkgo biloba, for instance, contained black walnut, which can be deadly for people with nut allergies. Bottles labeled as St. John’s wort were made of nothing but rice. One bottle even contained Alexandrian senna, a powerful laxative made from an Egyptian yellow shrub.

“Most of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers,” researchers concluded in a study published in the journal BMC Medicine. “These activities dilute the effectiveness of otherwise useful remedies, lowering the perceived value of all related products because of a lack of consumer confidence in them.”

Product substitution occurred in 30 of 44 of the products tested in the Canadian study and only two of the 12 companies had products without any substitution, contamination or fillers. “Some of the contaminants we found pose serious health risks to consumers,” researchers noted.

The herbal supplement industry is a $5 billion industry. According to CNN, more than half of U.S> adults take some kind of supplement, including multivitamins, minerals and herbs. The supplement industry as a whole is worth $27 billion, and is expected to continue rising as it has since the late 1980s. There are now over 29,000 different products available on the market, Healthy Living noted.

And unlike other drug products, the U.S. Food and Drug Administration does not regulate dietary supplements with the same scrutiny it applies elsewhere. Supplement makers do not have to prove that their products are safe or effective; it’s essentially an honor system.

"There's a false perception that supplements fall under the same regulatory umbrella as prescription drugs," Dr. Orly Avitzur, a medical adviser for Consumer Reports, told CNN in 2011. "That's not the case."

And part of the problem lies with consumers, as well. Many people assume that if their local pharmacy or health food store carries a particular herbal supplement, it can’t be harmful.

“Overall, I would agree that quality control is an issue in the herbal industry,” Stefan Gafner, the chief science officer at the American Botanical Council, told The New York Times. “But I think that what’s represented here is overblown. I don’t think it’s as bad as it looks according to this study.”

The method of DNA barcoding researchers used was previously applied to herbal teas. One study of herbal teas found that over a third of herbal products contained dried plant fragments not labeled on the ingredients.