Why Dietary Supplements are Suspect, from the April 2016 Harvard Women's Health Watch

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Evidence indicates that few supplements are effective and some may be harmful. Moreover, the products may not contain what their labels claim they do.

Dietary supplements — including herbs, vitamins, minerals, and other products — are a $37 billion industry in the United States, and 60% of women take them regularly. At the same time, a growing pile of research is suggesting that supplements — even mainstays like calcium — may be harmful at high doses.

Dr. David Eisenberg, adjunct associate professor at the Harvard T.H. Chan School of Public Health, was the first to document the widespread use of alternative therapies in the United States. “There are many research publications that suggest that some supplements may be useful and that Chinese herbs likely hold promise, but researching them — both individually and in combinations — as they are used clinically is technically very challenging,” Dr. Eisenberg says. “The absence of well-designed research involving many herbs and supplements, in part due to the fact that these tend not be patentable and financially protectable, does not necessarily correspond with a total absence of efficacy.” 

The lack of research can also be traced to the way supplements are regulated. Although some supplements have be examined in government-funded clinical studies, manufacturers aren’t required by the FDA to conduct clinical studies of the products and submit evidence that they are safe and effective for treating specific conditions.

Unfortunately, there is no guarantee that the supplements that showed promise in government-funded studies are the same products sold over the counter. The supplements used in government-funded studies were analyzed for purity and standardized by dose. However, recent investigations have determined that many of the thousands of supplements on the shelves haven’t been held to the same standards. In fact, many do not contain the very substances listed on their labels, and some have been found to contain potentially harmful contaminants that aren’t listed among the ingredients.

Read the full-length article: "Why supplements are suspect

Also in the April 2016 issue of Harvard Women's Health Watch:

  •     Why Harvard experts have a beef with the new meat guidelines
  •     Breast cancer: The good news
  •     Why you may need a statin
  •     How to work around a minor hearing loss

Harvard Women's Health Watch is available from Harvard Health Publications, the publishing division of Harvard Medical School, for $20 per year. Subscribe at http://www.health.harvard.edu/newsletters/womens or by calling 877-649-9457 (toll-free).

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Kristen Rapoza
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