Herbal Supplements - A New Study

Air Date: 
Thursday, November 14, 2013
Tom Shipka

In a recent commentary I argued that we should be skeptical about alternative medicine because, contrary to conventional medicine, its claims are not confirmed by science and it is unregulated by the FDA (Food and Drug Admistration). New evidence has now surfaced about herbal supplements, a staple in alternative medicine, which underscores the need for such skepticism. The evidence appears in an important research study in Canada which was published last month in the journal BMC Medicine (1) and reported this month in The New York Times (2).

The study was led by Steven G. Newmaster of the Biodiversity Institute of Ontario at the University of Guelph. He and his colleagues genetically tested forty-four bottles of popular herbal supplements sold by twelve companies in Canada and the United States. Here is what they found:

  • The products of only two of the twelve companies contained the ingredients listed on the label while the products of the other ten companies contained substitutions or adulteration with fillers, such as rice, soybean, or wheat, which were not listed on the label. In fact, the products of two of these ten companies contained none of the ingredients listed on the label. (3)
  • Bottles of Echinacea, a supplement used by millions to prevent or treat colds, were found to include a bitter weed and a plant which has been linked to rashes, nausea, and flatulence. (4)
  • Two bottles sold as St. John’s wort, a supplement widely used to treat depression, were found to include none of this herb.  One bottle contained rice and the other an Egyptian shrub called Alexandrian senna which is a powerful laxative. (5) 
  • Bottles of gingko biloba, a supplement marketed as a memory enhancer, were found to include fillers and black walnut, a hazard to people who are allergic to nuts. (6)
  • A bottle sold as black cohosh, a supplement used to treat hot flashes and other problems associated with menopause, turned out to be a bottle of a plant – Actaea asiatica - that can be toxic to humans; and (7)
  • One-third of the supplements tested showed "outright substitution," that is, there was "no trace of the plant advertised on the bottle." (8)

And what was the reaction to the study? On the one hand, a senior nutritionist at the Center for Science in the Public Interest - David Schardt - concluded that the study shows such a serious lack of quality control that people who recommend herbal supplements should stop doing so. On the other hand, spokespersons for the supplement industry - Stefan Gafner of the American Botanical Council and Duffy McKay of the Council for Responsible Nutrition - insisted that the study exaggerated the problem and that the herbal supplement industry can improve quality control without government interference. (9)

Meanwhile, in the wake of the study, three things seem clear:

  • Firstly, herbal supplements may be both ineffective and dangerous,
  • Secondly, there are very few safeguards in place to protect supplement users, and
  • Thirdly, given the political clout of the National Health Federation and other organizations which promote the interests of alternative medicine, change is unlikely. 

So, to buyers of herbal supplements, I invoke a Latin warning from the 1500s: Caveat emptor! - "Let the buyer beware!"

  1. Steven G. Newmaster et al., "DNA Barcoding Detects Contamination and Substitution in North American Herbal Supplements," BMC Medicine, October 2013, 11:22.
  2. Anahad O’Connor, "Pills That Aren’t What They Seem," The New York Times, November 5, 2013, p. D1, p. D5.  
  3. Ibid., p. D5.
  4. Ibid., p. D1.
  5. Ibid., p. D1.
  6. Ibid., p. D1, p. D5.
  7. Ibid., p. D5.
  8. Ibid., p. D5.
  9. Ibid., p. D5.