Dr. Timothy CannonTimothy L. Cannon, MD, is board certified in medical oncology, hematology and internal medicine. His specialty is managing gastrointestinal cancers. Dr. Cannon emphasizes personalized care for his patients and is interested in pharmacogenomics as well as using technology to improve patients’ access to care. Read Dr. Cannon’s profile.

An employee once told me that she spent one-third of her take-home salary on nutritional supplements. When I asked her why, she replied, “There is no replacement for good health.”

My next question was why she believed that the supplements promote good health. She gave me two reasons:

  • They are natural.
  • People have been taking them for many years.

Supplements: Does “Natural” Equal “Good?”

Many cancer patients that I treat are drawn to treatments that are marketed as “natural.” Marketing literature for health products typically uses “natural” as a synonym for “good.” This is a one-sided view of nature, of course, but health product marketers usually omit the potentially threatening aspects of nature. Eula Biss, in her book “On Immunity,” pointedly remarked that our understanding of nature as a synonym for good is a sign of our profound alienation from it.

When it Comes to Supplements, More Isn’t Better

According to this article, vitamins, minerals and other supplements may be great in normal amounts. However, they can be dangerous in excessive amounts—and it can be easy for a person taking supplements to unknowingly consume excessive amounts.

Could an Excess of Vitamins Cause Cancer?

Beta carotene and vitamin A supplementation, which at one point doctors thought might prevent cancer, actually seem to promote some types of cancer. Similarly, results from another trial suggested that selenium and vitamin E may increase the risk of prostate cancer and diabetes, respectively.

Though we don’t fully understand how some vitamins may promote cancer growth, the possible link between excessive supplements and cancer is concerning. In addition to causing health problems, I have seen many patients (and relatives) incur financial debt from the expense of supplementation.

Supplements Need Clinical Trials, Too

We know now that having more of a vitamin, mineral or natural product is not always safe. This leads us to question the wisdom of selling supplements without first testing them in clinical trials.

Many times, patients who take one supplement take many. Since most physicians do not see enough patients taking any one supplement frequently enough, they are unable to notice a dangerous trend. Therefore, it is unlikely that the medical community will recognize the potential dangers of some supplements. The solution may be to require specific clinical trials for individual supplements.

To Supplement or Not: Talk to Your Doctor First

It is always important to talk to your doctor before taking (or stopping to take) any type of supplement. If you take a multivitamin every day, that may be a healthy and even necessary part of your diet. Treat supplements as you would any type of medicine, and discuss them with your physician.

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