DEAR DOCTOR K:
What is an antioxidant? Should I be taking an antioxidant supplement?
Something terrible often happens to medical scientists: A beautiful theory is murdered by a brutal gang of facts.
The theory that vitamin pills with antioxidant powers — primarily vitamins A, C and E — could slow aging, fend off heart disease, improve flagging vision and curb cancer was beautiful and very plausible. As a result, some doctors urged their patients to take such vitamin pills daily.
To understand why the theory was taken very seriously, a few basics are in order.
As the cells in our body do their different jobs, they need food, and they produce waste. One kind of waste is a group of chemicals called “free radicals,” which occur naturally as byproducts of body processes, such as burning fat. They are also created by environmental factors such as tobacco smoke, ultraviolet rays and air pollution.
Free radicals are described as “unstable” because they lack a full set of electrons. This leads them to steal electrons from other molecules. When they steal these electrons, they damage those other molecules. The process of stealing electrons is called oxidation.
Antioxidants can chemically combine with free radicals, rendering them harmless. They prevent oxidation — that’s why they’re called antioxidants.
Since we know that oxidation can damage tissues — contributing to the aging and death of cells — it made sense that antioxidants might be good for our health. We also knew that many foods that are rich in natural antioxidants definitely were good for our health. That didn’t prove that it was the antioxidants in the foods that led to improved health; it could be something else in the foods. But it gave support to the theory that vitamin pills with antioxidant power would be good for our health.
Some scientists find their theories so attractive that they don’t need testing. 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 has been spent in testing it.
Unfortunately, results from well-designed trials of antioxidant supplements have failed to back up many of the claims of benefits. One study pooled results from 68 trials with more than 230,000 participants. It found that taking antioxidant supplements is unlikely to help you live longer. Sixty-eight rigorous studies, involving hundreds of thousands of people whose health was followed for many years, that fail to show evidence in support of a theory are a brutal gang of facts.
On the other hand, foods rich in antioxidants definitely 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. So get your antioxidants in the form that nature has provided them to us: in food, not pills.