DEAR DOCTOR K >> It seems like several years ago all my friends were taking antioxidant pills. Now I don't hear about antioxidants as much. Are they worth taking?

DEAR READER >> Here's what we know, and here's what is still controversial. The cells of our body are full of chemicals interacting with other chemicals. In the process of getting the energy they need to survive and carry out their functions, cells naturally produce chemicals called "free radicals." Just as political free radicals can sometimes damage society, chemical free radicals can damage body tissues.

Our environment also exposes us to substances that increase our production of free radicals. Examples are tobacco smoke, ultraviolet rays and air pollution.

To fight the effect of free radicals, our body makes natural antioxidant chemicals. We also get antioxidants in foods. In particular, several vitamins — primarily vitamins A, C and E — have antioxidant powers.

If the levels of antioxidants match the levels of free radicals, we're in balance. However, if free radicals exceed the antioxidants in our body, we're out of balance. This is called "oxidative stress." Frequent bouts of oxidative stress may increase the pace of aging.

There is very strong evidence that eating a lot of foods rich in antioxidants can help lower your risk of many diseases. Good food sources of antioxidants include fruits and vegetables, particularly tomatoes, kale, blueberries, onions and apples. Other good sources include dark chocolate, whole grains, coffee, green tea and vegetable oils. That's not controversial.


Here is where the controversy begins. As scientists came to better understand the balance between free radicals and antioxidants, a beautiful theory emerged. Perhaps, scientists thought, taking antioxidant vitamin supplements would slow diseases of aging. Perhaps these supplements would fend off heart disease, improve flagging vision and curb cancer. It was a theory worth testing.

Some scientists find their theories so attractive that they don't bother to test them. When that happens, they cease being scientists. Much more often, scientists put their theories to the test. Because the antioxidant vitamin pill theory was so compelling, a lot of time and effort was spent in testing it.

Unfortunately, results from well-designed trials of antioxidant supplements have failed to back up many of the claims of benefits.

To answer your question, I don't recommend that people routinely take antioxidant vitamin supplements. Your money is better spent elsewhere.

Dr. Komaroff is a physician and professor at Harvard Medical School.