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Herbal supplements — are they what they claim?
Only about half contain the claimed substances


By David Dunaief, M.D.

November 06, 2013

Millions of Americans take herbal supplements. In fact, a survey from 2007 showed that approximately 18% of Americans used herbal supplements in the previous year (Natl Health Stat Report. 2008). 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 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 BC (JAMA. 1998;280:1604-1609).

However, even with a long tradition, are they really safe and effective? Even more, are we getting what the label claims is in the bottle? It would be a frightening thought if we were not.

The problem lies with the fact that herbal supplements are self-regulated for the most part. Manufacturers must label them with a disclaimer, saying that the content and health claims have not been reviewed by the Food and Drug Administration 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 for benefit. They also may be harmful on several levels; some cause interactions with drugs, such as warfarin; some are incorrectly labeled regarding contents or doses; some include unlabeled medications and sometimes exceeding pharmaceutical doses; 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.

Contents of herbal supplements

We want to be certain that the contents in the bottle match what is on the label. Unfortunately, in a recently published study, results showed 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. They found that only 48% 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 not 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 found in the bottles. This is not the first time supplements have been tested, but this time researchers utilized 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, results show that as many as 25% of the bottles tested did not contain black cohosh (J AOAC Int. 2012 Jul-Aug;95:1023-1034). They tested 36 bottles acquired from brick-and-mortar chain stores and from online. David Baker, M.D., an OB/GYN professor, also utilized the DNA barcoding technique mentioned above.

Gingko biloba

Does Gingko biloba live up to its claim of helping improve memory or prevent dementia? Unfortunately, in the first large double-blinded randomized controlled trial, the gold standard of trials, results were disappointing (JAMA 2008;300:2253-2262). Gingko biloba was no better in preventing dementia or Alzheimer's disease than a placebo. There were over 3,000 participants in the trial; most did not have cognitive issues, but 14% had mild cognitive impairment at the start of the trial. The treatment group took 120 mg of Gingko biloba.

This is only one, albeit large, well-designed, study. But at least this supplement is safe, right? Well in a recent toxicology study using lab rats, results demonstrated an increased risk of developing cancer, especially thyroid and liver cancers, as well as nasal tumors ( 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 (Am Heart J. 2013;166:187-196). 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 Lab (, Center for Science in the Public Interest (, NIH National Center for Complementary and Alternative Medicine Herb Fact Sheets (, and Natural Medicines Comprehensive Database (


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.


This column was previously published in the Times Beacon Record Newspapers.