Your Weekly Checkup: Can Dietary Supplements Harm You?

A recent analysis found unapproved and sometimes dangerous drugs in 746 dietary supplements.

Pills in honeycomb shaped storage pods

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“Your Weekly Checkup” is our online column by Dr. Douglas Zipes, an internationally acclaimed cardiologist, professor, author, inventor, and authority on pacing and electrophysiology. Dr. Zipes is also a contributor to The Saturday Evening Post print magazine. Subscribe to receive thoughtful articles, new fiction, health and wellness advice, and gems from our archive.  

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I have written previously about dietary supplements and noted that half of American adults consume at least one dietary supplement daily. Most randomized clinical trials of vitamin and mineral supplements have not demonstrated clear benefits in preventing chronic diseases unrelated to nutritional deficiency. Moreover, the Food and Drug Administration does not review dietary supplements for safety and efficacy.

Dietary supplements include vitamins, minerals, botanicals, amino acids, and enzymes that are not intended to treat or prevent disease and are classified as a category of food not subject to the premarket safety and effectiveness testing required by the FDA for drugs. Many consumers think that these supplements are carefully regulated and that the label accurately lists the ingredients. This is often not the case because a less expensive ingredient can be substituted for a more expensive one listed on the label, or an active drug might be included in what is labeled as only a botanical supplement (see below).

While the FDA is tasked with identifying and removing unsafe products from the market to help ensure that products marketed as dietary supplements are safe, well-manufactured, and accurately labeled, it is often ineffective in doing so because of cumbersome, outdated, and unenforced regulations. The FDA relies on surveillance efforts after the drug is marketed, including review of adverse event reports and consumer complaints, inspection of dietary supplement firms, screening of imported products, and adverse reports from the dietary supplement firm.

When such a product is identified, the FDA frequently requests that the responsible firm voluntarily recall the product. However, many supplements subject to recalls remain on sale still adulterated with pharmaceutical drugs, sometimes years after the initial recall. Consumers of a supplement subject to a voluntary recall sometimes are unaware of the recall and continue to purchase the product.

An analysis of FDA warnings of contaminated supplements from 2007 through 2016 published recently found unapproved and sometimes dangerous drugs in 746 dietary supplements, almost all of them marketed for three categories: sexual enhancement, weight loss, or muscle growth. The most common adulterants were sildenafil (Viagra) for sexual enhancement supplements, sibutramine (an adrenaline-like drug sold under the brand name Meridia and withdrawn from the U.S. market in 2010) for weight loss supplements, and synthetic steroids or steroid-like ingredients for muscle building supplements. Fluoxetine, a prescription antidepressant (Prozac), was found in 17 of 317 weight loss products.

About 80 percent of the supplements were contaminated by one pharmaceutical, 20 percent contained more than one unapproved ingredient, and two of the supplements contained six unapproved drugs. Despite these contaminants, fewer than half the products were recalled.

Twenty-eight products were named in multiple FDA warnings, with nineteen (67.9%) still containing new unapproved ingredients in the second or third warning, indicating the FDA found the product to be adulterated more than once.

An editorial accompanying the article cited above noted that in the current study, the FDA discovered 746 supplements to be adulterated but announced voluntary recalls for only 360, leaving more than 350 adulterated supplements still available for sale. The editorial called for reform of the Dietary Supplement Health and Education Act of 1994.

It is clear that active drugs continue to be found in dietary supplements, even after FDA warnings, because of major deficiencies in the FDA’s regulation of supplements. The drug ingredients in these dietary supplements have the potential to cause serious adverse health effects owing to inappropriate use, interaction with other medications, underlying health conditions, or other pharmaceuticals within the supplement.

In the meantime, my advice for those who ingest dietary supplements: Caveat emptor. Let the buyer beware.

Also read Vitamin Hype: Are You Wasting Your Money on Supplements?

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