Dietary supplements can be a dangerous mix with traditional drug therapies

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Nearly 70% of us take dietary supplements, according to to the Council for Responsible Nutrition. But researchers at the University of Minnesota in Minneapolis are examining how those supplements we take can have a negative impact on the efficacy of certain cancer drugs.

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Beware of these mixes

Here are a few examples of what researchers are examining right now, according to the Wall Street Journal:

  • Echinacea is thought to boost your immune system, but it can possibly reduce the effectives of the breast cancer drug tamoxifen.
  • Kava is known as a anxiety and stress reliever, but it may hamper the efficacy of another breast cancer drug as well.
  • Fenugreek is used to help cancer treatment, among other things, but it may increase the effects of blood thinners.
  • Saw palmetto is used to stop prostate cancer growth, but it too may increase the effects of blood thinners and NSAIDs (Nonsteroidal anti-inflammatory drugs.)

The problem with mixing herbs and traditional medication is that the herbs can speed up or slow down the absorption of the medication into your body. That’s because of the influence herbal remedies have on important enzymes in your body.

So if you’re taking any kind of herbal remedy or dietary supplement and also taking traditional medication, be sure your doctor knows. Unfortunately, the sad reality is some studies suggest as many as 70% of patients don’t inform their physicians about use of supplements.

At the very least, be sure to take a look at Memorial Sloan Kettering Cancer Center’s About Herbs database, which is a tool for the public as well as healthcare professionals, to help figure out the value of using common herbs and other dietary supplements. They do a great job of spelling out the potential interactions with conventional drug therapy.

Are your herbal supplements what they claim to be?

Another issue with herbal remedies is purity. The attorney general of New York State tested a variety of herbal remedies at Walmart, Walgreens, Target and GNC. Four out of five products did not contain *any* of the herbs listed on the labels, according to The New York Times. Instead, they contained other ingredients that could be life threatening to some people.

(Each retailer has pledged to cooperate, more or less, with the attorney general in an effort to improve the safety of consumers who take herbal supplements. Walgreens, in particular, is removing all the tested products that failed from all stores across the US. That’s been the most strident response so far.)
The thing is, these are not isolated results. This is a common problem that’s been detailed again and again.

In a 2013 study published in the journal BMC Medicine, Canadian researchers tested 44 bottles of herbal supplements bought in Canada and the United States. A full one-third of the samples tested were adulterated; they did not have any of the key ingredients they promised.

Cheap fillers like rice, soybean, and wheat were used in place of actual ingredients people were paying big money to take, according to The New York Times. (The study’s authors decided *not* to reveal any product names to avoid singling out a sole company.)


There’s no foolproof way to protect yourself as a consumer, but Clark suggests you only buy USP (United States Pharmacopeia) certified supplements. The USP seal is the mark of the industry’s attempt at self-regulation. Other than that, know it’s buyer beware and you could be buying anything.

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