Contaminated Dietary Supplements at Health Food Stores

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Isn’t it terrible to think that you can take something to improve your health that instead endangers your life? Yet, that’s what can happen if you take a dietary supplement contaminated with toxins or dangerous drugs. Don’t make the mistake of thinking that this is an obscure problem, because it is not. In fact, in 2009, the US Food and Drug Administration (FDA) discovered that dozens of dietary supplements contained active pharmaceutical ingredients — meaning prescription drugs — not listed on their labels. Experts believe that the more than 140 contaminated products that the agency has exposed so far are just the tip of the iceberg, with many more currently on shelves and available for sale.

Pieter A. Cohen, MD, an associate residency director at Cambridge Health Alliance in Massachusetts, sounded an alarm with his article “American Roulette — Contaminated Dietary Supplements,” in The New England Journal of Medicine last October. When I called to ask about the report, Dr. Cohen told me that he’d noticed a pattern among patients taking what they thought were “natural” weight-loss pills who were experiencing significant side effects. “We found that these pills actually contained potent prescription medications,” he said. He added that it’s important for people to realize that when you buy a drug such as aspirin, you know that the FDA scrutinizes such products and therefore, barring manufacturing mistakes, you can rely on the fact that what is on the label is what is in the bottle. But when you buy a supplement, there’s a greater possibility that it may contain undeclared prescription medications… drugs rejected by the FDA due to safety concerns… toxic metals, such as lead or mercury… bacteria… or pesticides.

A few particular types of supplement are more dangerous — you’ll learn why in a minute. Before that, though, it’s important to know why such potentially harmful products are being sold in stores in the first place — so you know how to protect yourself.

Going in the Wrong Direction

Supplement manufacturers once had to demonstrate that their products were safe before they could sell them. That’s no longer the case. Under the 1994 Dietary Supplement Health and Education Act (DSHEA), a federal law, the official presumption is that supplements are safe unless or until proven otherwise. No clinical trials are required before a product is marketed, and if a problem arises, the burden is on the FDA to prove that it’s unsafe before taking action to restrict its use or to pull it off the market. Many people erroneously assume “natural” means “safe” and they think, therefore, that these products are less likely to be harmful than pharmaceuticals — but the problems that arise usually are due to ingredients not listed on the label.

Of course, it is illegal to sell tainted products, and reputable companies don’t. But the lack of oversight can make it easy for unscrupulous supplement manufacturers to sell adulterated products. In one study, researchers found that more than one-third of dietary supplements claiming to treat erectile dysfunction (ED) or to otherwise enhance male “performance” contained undisclosed prescription drug ingredients — the same ones in those drugs you see advertised on TV. This is bad news — the reason they require a prescription is that it’s dangerous for certain people, such as those on heart medications.

The Worst Supplements of All

Any type of supplement could potentially be contaminated with poor-quality, even toxic ingredients. But one of the most potent dangers — the presence of active pharmaceutical medications — is most likely to be found in three categories of products: those for sexual enhancement…for weight loss… and for athletic performance. Also be wary of products marketed not just for general health but for particular conditions — such as diabetes, insomnia or high cholesterol — which are likely to contain numerous ingredients and thus pose a greater risk.

How to Buy Safe Supplements

Whatever supplement you take, be very particular. Dietary supplements are not required to be standardized in the US, so an herb from one company may be completely different in quality and potency from what is ostensibly the same herb from another company. In addition, manufacturers are not required to list the country of origin of ingredients — so a botanical medicine “made in the USA” may contain herbs from another country. While plenty of high-quality herbs are imported, others are farmed under conditions we’d consider unacceptable, such as using toxic pesticides or grown in soil contaminated with lead or mercury.

steps to take

Work with a doctor who is trained in evaluating the products. For instance, naturopathic physicians are well-schooled in how to identify quality natural-product manufacturers.

  • Look for supplements with a USP stamp on their labels. The US Pharmacopeia (USP) is an independent organization dedicated to quality control that tests products and visits sites of companies that join their program. Dietary-supplement manufacturers are not required by law to follow USP standards, but some do so voluntarily.
  • Single-ingredient products can be a safer choice. Other than multivitamins, the supplements with more ingredients have a greater likelihood that they’ll contain contaminants or have harmful side effects.
  • Start taking only one new supplement at a time. This allows you to know what might be causing any side effects such as a rash, diarrhea, constipation or insomnia.
  • Avoid weight-loss, erectile dysfunction and athletic-performance supplements unless recommended by your doctor or trained practitioner.
  • Report any suspected adverse effects from a supplement to the FDA — this is especially important given that, at present, such reporting is the best mechanism we have to get dangerous products off the market. File a report at
  • Talk to your doctor. Make sure he/she is aware of and up-to-date on all supplements you take, and discuss dosage, possible interactions and other safety issues.

Pieter A. Cohen, MD, associate residency director, Cambridge Health Alliance, Somerville, Massachusetts, instructor, Harvard Medical School, Boston, Massachusetts

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