By John Messmer, MD

Vitamins, minerals and other nutrients from lycopenes to green tea extract are touted for their anti-cancer, immune system enhancing, and age-delaying properties. There are many claims that vitamin E, vitamin C, vitamin A and its precursor, beta carotene, reduce the risk of heart attacks and cancer through their antioxidant effects.

Foods with high levels of antioxidants

Research has shown that people who eat a Mediterranean diet, one rich in foods that contain high levels of antioxidants, have lower rates of heart disease. People who consume green tea in large amounts have reduced cancer rates. And there is evidence that frequent consumption of tomato products can reduce the risk of prostate cancer. From data such as this, many people have concluded that taking antioxidants in pill form will do the same thing. The problem is that in the body, taking a pill is not the same as eating the food.

Oxidation and free radicals

Oxidation is the process by which oxygen combines with something. When our blood is oxidized, that's good - oxidized blood brings oxygen to our tissues to keep them alive. Oxidation takes place throughout our bodies in the process of making energy for our bodies to work correctly.

Sometimes oxidation is a bad thing. Fruits and vegetables that are in contact with oxygen in the air eventually spoil and turn brown. Butterfat will turn rancid after prolonged exposure to oxygen. In our bodies, oxidized LDL cholesterol (the "bad" cholesterol) sticks to and clogs our arteries. In some areas, the oxidizing process creates electrically charged molecules called "free radicals" that can interact with other parts of our cells.

Our immune systems use certain free radicals in a good way to help us kill infection. However, the electric charge can damage DNA and proteins in our cells. DNA damage can lead to cancer, and damage to structural proteins can cause aging changes. Proponents of antioxidant supplementation reason, therefore, that an antioxidant could prevent this problem.

Is it the food or a component of the food?

No one really knows if it's the lycopenes in tomatoes and the catechins in green tea that reduce the risk of cancer; or if it's the vitamin E and omega-3 fatty acids in a Mediterranean diet that reduce the heart disease risk; or if the benefit actually comes from something else. Perhaps it's the food itself that helps fight disease, not a concentrated dose of some part of the food. So why not use supplemental antioxidants anyway, just in case? Because studies of supplementation with vitamin E and beta carotene have shown increased risks of heart disease and cancer.

Good health: diet, exercise & no smoking

There are no shortcuts to good health. It is well established that a diet rich in a variety of different colored fruits and vegetables with whole grains, seeds, and nuts is the most healthful in the long term. It helps us keep our immune systems in good working order and can lower the risk of heart disease and cancer. However, it is important to realize that diet is only part of the picture. Tobacco avoidance, regular exercise, and maintaining a normal weight are essential.

So, are antioxidants good or bad?

Some people claim that doctors don't want you to know about the health benefits of antioxidants. It's silly to think that doctors would intentionally avoid using something helpful. With no evidence of benefit and some evidence of harm, it's understandable why physicians do not recommend antioxidant supplements routinely.

There is one exception, however. In age-related macular degeneration (AMD), there is evidence that certain antioxidants can slow the progression of the problem once it's developed. There is no evidence that supplements can prevent it although a good diet, avoidance of ultraviolet light, and not smoking do reduce the risk.

Unless recommended by a physician for a specific reason, for now it's best not to use antioxidant supplements. No one has any scientific evidence of consistent benefit, and they may cause harm. The best thing to do is to eat a varied diet that includes foods with antioxidants, rather than consuming the antioxidants themselves.