Caveat Emptor With Herbal Supplements

Aug 19, 2015
Millions of Americans take herbal supplements. In fact, a survey from 2007 showed that 18 percent of Americans used herbal supplements in the previous year...

Millions of Americans take herbal supplements. In fact, a survey from 2007 showed that 18 percent of Americans used herbal supplements in the previous year (1). Many take them on a daily basis, hoping they will prevent disease, keep them healthy, or even help treat disease, with or without conventional drugs. Many think that herbal supplements, unlike most medications, are natural substances, and therefore are likely to be safe.

Herbs have been used for thousands of years. Hippocrates, the father of medicine, recognized that there may be potential benefits of taking St. John’s wort for the treatment of mood disturbances. Another substance, saw palmetto, was used by the Egyptians for urinary tract problems in the 15th century B.C. (2).

However, even with a long tradition, are they really safe and effective? Even more, are we getting what the label says is in the bottle? Earlier this year, the NYS Attorney General performed DNA tests on 78 bottles of herbal supplements at Target, GNC, Walmart and Walgreens. Eighty percent did not contain the labeled ingredients, and some contained high levels of mercury, arsenic and lead (3). They also contained some substances that patients may be allergic to when the label on the bottle claimed otherwise.

The problem lies with the fact that herbal supplements are self-regulated. Manufacturers must label them with a disclaimer, saying that the content and health claims have not been reviewed by the FDA and that they are not meant to treat or prevent disease. Would you be comfortable buying drugs that were self-regulated? Probably not!

Many think the worst thing that could happen is they don’t help. Unfortunately, this may not be the worst effect. They may or may not work – the research on most is not very compelling. They also may be harmful on several levels: some cause interactions with drugs, such as Coumadin; some are incorrectly labeled regarding contents or doses; some include unlabeled medications in the bottles; and some cause side-effects. Just because they are said to be natural, doesn’t mean they’re safe.

Let’s look at the evidence.

Content of herbal supplements

We want to be certain that the contents in the bottle match what is on the label. Unfortunately, the recent investigation isn’t the first time the issue has been raised. An earlier study found that not all herbal supplements contain what is claimed, and some contain potentially harmful contaminants or inaccurate concentrations. Canadian researchers tested 44 herbal supplements from a dozen companies in the U.S. and Canada (4). They found that only 48 percent contained the herb that was on the label. In addition, about one-third of these supplements also contained fillers or contaminants. For example, a bottle labeled St. John’s wort actually contained a laxative from a plant called Alexandrian senna, and no St. John’s wort. With two other popular herbs, ginkgo biloba, used for memory, and echinacea, used to treat or prevent colds, there were fillers and potentially harmful contaminants in the bottles. These were identified using a sensitive DNA testing technique called DNA barcoding.

Black Cohosh

Black cohosh is used by women to help treat vasomotor symptoms, specifically, hot flashes associated with menopause. In a local study done at Stony Brook University Medical Center, as many as 25 percent of the bottles tested did not contain black cohosh (5). They tested 36 bottles acquired from brick-and-mortar chain stores and online. David Baker, M.D., an Obstetrics/Gynecology professor, also utilized the DNA barcoding technique mentioned above.

Ginkgo Biloba

Does ginkgo biloba live up to its claim of helping improve memory or prevent dementia? Unfortunately, in the first, large, double-blinded, randomized controlled trials (RCT), the gold standard of trials, results were disappointing (6). Ginkgo biloba was no better in preventing dementia or Alzheimer’s disease than a placebo. There were more than 3,000 participants in the trial; most did not have cognitive issues, but 14 percent had mild cognitive impairment. The treatment group took 120 mg of ginkgo biloba.

This is only one, albeit large, well-designed, study. But at least this supplement is safe, right? Well, in a toxicology study using lab animals, results demonstrated an increased risk of developing cancer, especially thyroid and liver cancers, as well as nasal tumors (7). Researchers point out that, while this is an interesting finding, it does not mean necessarily that the results are transferable to humans. Also, the doses used in this toxicology study were much higher, when compared to those taken by humans.

Red yeast rice and Phytosterols

Lest you think that herbs are not effective, red yeast rice is an herbal supplement that may be valuable for treating patients with elevated levels of cholesterol. In a study in patients with high cholesterol who refused or had painful muscle side effects from statin treatment, results showed that red yeast rice and lifestyle changes were effective in lowering LDL “bad cholesterol” levels (8). Patients making lifestyle changes alone were able to lose weight and maintain lower LDL levels over one year. The patients taking red yeast rice maintained LDL reductions over the year, as well. When phytosterols were added for patients taking red yeast rice, there was no further improvement in cholesterol levels. Again, some herbs may be effective, while others may not.


By no means are all herbs suspect, but you need to perform some due diligence. What can be done to make sure that doctors and their patients are more confident that the herbal supplements contain what we think? Well the best would be if an agency like the FDA would oversee these products. However, since that has not happened yet, there are resources available. These include Consumer Labs (www.Consumerlabs.com), Center for Science in the Public Interest (www.CSPInet.org), and NIH National Center for Complementary and Alternative Medicine Herb Fact Sheets (www.nccam.nih.gov/health/herbsataglance.htm), and Natural Medicines Comprehensive Database (www.naturaldatabase.com).


When taking herbal supplements, it is very important that patients share this information, including the brand names and doses, with their doctors and pharmacists. Herbal supplements may interact with medications, but they also may not contain labeled ingredients, and could have detrimental effects. If you have symptoms that are not going away, it could be due to these supplements. The best natural approach is always lifestyle modification.

Herbal supplements are sorely lacking proper regulation. So caveat emptor — buyer beware when it comes to taking herbal supplements.


(1) Natl Health Stat Report. 2008. (2) JAMA. 1998;280(18):1604. (3) NYTimes.com. (4) BMC Medicine 2013, 11:222. (5) J AOAC Int. 2012 Jul-Aug;95(4):1023-34. (6) JAMA 2008;300:2253. (7) ntp.niehs.nih.gov. (8) Am Heart J. 2013;166(1):187-196.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com or consult your personal physician.