To Supplement, or Not to Supplement - WebMD (blog)

By Heather Millar

I’m not much of a vitamin person. That is, I don’t take a lot of multi-vitamins and other dietary supplements. This pill aversion probably results from the experience of growing up in California in the 1970s. In those days, it seemed that every other week some new plant distillation or vitamin or essential mineral was hailed as the key to eternal youth and disease-free living. I guess I suffer from “vitamin-fatigue.” I try to eat a balanced diet and leave it at that.

Still, I know a lot of cancer patients and survivors who believe passionately that taking this or that over-the-counter pill will help to defeat their cancer, or to maintain a remission. Nutrition supplements have become a multi-billion dollar industry. About half of all American adults take some sort of supplement.

I don’t know if all those people are right, or wrong, but a recent commentary from the Journal of the National Cancer Institute at least suggests that some caution is in order.

The paper says that three common supplements may be harmless when taken at three times the recommended dose, but may cause cancer at the much higher doses recommended by some supplement companies.

Researchers from University of Colorado, UC San Diego, University of Arizona and University of North Carolina considered the following:

• Beta-carotine. A form of Vitamin A, good for your eyes, the stuff in carrots.

• Selenium. A trace mineral that helps to make enzymes that fight cell damage from so-called “free radicals,” by-products of oxygen metabolism that are thought to contribute to chronic diseases like cancer.

• Folic acid. The synthetic form of folate, a B-vitamin necessary to produce and maintain new cells. It also helps prevent the DNA damage that may lead to cancer.

All those things sound good, right? But the researchers found that if a little is good, a lot is not necessarily better. For instance, the Food and Drug Administration write-up on selenium, linked above, says that people only need it in trace amounts. Taken at high doses, these three supplements have been shown to increase the risk of a host of cancers.

Whenever you think that you’ve found the vitamin that will change your life, it’s a good idea to remember that the FDA does not regulate supplements as drugs, which must clear a very high bar before being approved for sale. Instead, supplements must only meet the federal standards for food safety, a much lower bar.

And it’s also good to remember that while our understanding of vitamins and biology has increased since vitamins were first isolated in 1905, our knowledge remains far from comprehensive.

As one of the commentary’s senior authors, Tim Byers of the Colorado School of Public Health, told Science Daily ,“We have a window into less than half of the biology of what these nutrients are doing. We say generalized things about them, calling them an antioxidant or an essential mineral, but true biology turns out to be more complex than that. The effects of these supplements are certainly not limited to the label we give them. And, as we’ve seen, sometimes the unintended effects include increased cancer risk.”

The authors call for the government and the science community to provide clearer guidance about taking supplements to lower cancer risk. This seems sensible to me.

So what do you think? Do you take vitamins, or not? Why, or why not?

Photo: iStockphoto