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Supplement Savvy for Cancer: The Antioxidant Controversy

By Jill Place, MA, RD

One of the biggest questions that you may have during chemotherapy or radiation is to antioxidant or not to antioxidant. An antioxidant is a nutrient or other substance that finds and stops free radicals cold. Free radicals are atoms with an odd number of electrons. These electrons want to pair up with other electrons. So they run around trying to find another electron to marry. While they're running around, they can cause damage to DNA or cell membranes. This damage may cause cancer. Antioxidants marry with free radicals and stop them from doing damage.

Now you might think that antioxidants may be a good thing when you're in treatment because chemotherapy and radiation may make free radicals. But before you make a decision about whether to take antioxidants during treatment, it's important that you first understand how supplements are tested.

There are three major ways that supplements are tested. One is the test-tube-type test, which is called in vitro. Scientists put something they want to test in a tube or dish, like cancer cells. Then they add something that may stop the growth of these cells, like an antioxidant, and see what happens. When the test-tube study goes well, scientists try out their theories on animals. The second type of study is the animal study, also called an in vivo study, which literally means "in life". Scientists put the same ingredients in an animal and see if they get the same results as in the test tube study. If they do, they move on to tests with humans.

Antioxidants have been tested quite successfully in in vitro and animal studies. But there have been few human studies that show that they work. Also, some human studies have shown the opposite effect from successful in vitro and animal studies. The Finnish Smokers' Study showed that Beta-carotene, an antioxidant, caused cancer instead of preventing it.

Because, human studies don't always have the same results as test-tube or animal studies, antioxidants shouldn't be okayed for use for the general public unless they're tested on humans. There's been some thought that they can protect cancer cells as well as normal cells from the oxidation that causes free radicals. If this is true, your chemotherapy or radiation treatments may not be as effective. In other words, there's a possibility that your treatment may not kill every cancer cell like it's supposed to do if you take antioxidants.

Some clinicians have also said that it's okay to take multivitamins that contain antioxidants during treatment. But there have been studies with small amounts of antioxidants that have suggested that they might promote cancer growth. Multivitamins may be safe, but it's impossible to say so without further testing because of the negative studies on small doses of individual antioxidants.

A large human study is now being done in India using large oral doses of a combination of antioxidants such as Vitamin C, Vitamin E, Vitamin A, and mixed carotenoids. Until the results of this study, and more like it, are done successfully, it might be a good idea to stop using antioxidants and multivitamins containing antioxidants one to two weeks before treatment and to begin one to two weeks after treatment.

There are other nutrients that may help reduce symptoms and keep you from being malnourished during treatment. And you also get smaller amounts of antioxidants in the foods you eat. Antioxidants in food are okay to have during treatment because they're not present in the high doses that you can get with supplements. So ask your dietitian or Supplement Savvy Specialist about foods and supplements that are okay to have during treatment. And save your antioxidants and multivitamins to use afterwards.

© Copyright 2002 Jill Place, MA, RD