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updated 12/30/2004 3:49:47 PM ET 2004-12-30T20:49:47

It’s common knowledge that antioxidants protect us from dangerous substances called free radicals that can create damage leading to many chronic diseases. Yet scientists say there is more to learn about the health benefits of antioxidants.

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Studies demonstrate that vegetables, fruits and whole grains supply an abundance of vitamins and natural phytochemicals that act as antioxidants. A greater consumption of these antioxidant-rich foods has been shown to lead to higher blood levels of antioxidant power.

Studies also show that when people eat diets high in antioxidants, their risk of cancer and heart disease decreases. However, if antioxidant vitamins and phytochemicals are responsible for the health benefits seen, antioxidants from supplements may not yield the same results.

A higher dose of antioxidants from supplements could actually be counterproductive by upsetting the natural balance of antioxidants in the body.

The various kinds of antioxidants are now believed to work in different parts of the body. People may also vary in their need for each kind of antioxidant, depending on how much damage from free radicals, or oxidation damage, they are exposed to from tobacco smoke, overeating and other influences.

To measure the amount of oxidation damage in a person, researchers examine certain biomarkers or physical signs. The level of biomarkers is usually determined through blood sample tests.

Elevated biomarkers of DNA damage are linked to cancer risk. Signs of damage to blood vessel walls and oxidation of LDL cholesterol are connected to heart disease risk. Some research even suggests that oxidation damage to nerves may be linked to age-related brain changes. Although oxidation damage has been liked to these diseases, this damage cannot be said yet to cause them.

One reason that the effect of antioxidants on disease is still unsure is that many studies of antioxidants use people known to be at an increased risk.

For example, scientists will see if antioxidants offer any protection against heart attacks to people who have already had one. Since antioxidants seem to offer protection from damage that occurs early in the development of diseases, these studies may miss measuring some of the impact of antioxidants. In later stages, other factors may be more decisive.

Boost intake through diet
At one time, people thought that oxidation damage to cells was always bad. But studies now show that certain highly reactive compounds (free radicals) stimulate cancer cells to commit suicide.

Radiation and chemotherapy work in this way. That is why many experts recommend avoiding antioxidant supplements during chemo and radiation therapy. The body may naturally combat the early stages of cancer, too, in this way, when abnormal cells are forming.

Consequently, scientists are working to discover the amounts and combinations of antioxidants that best protect our cells without interfering with this natural defense mechanism.

For now, you would be wise to limit major sources of oxidation damage and boost your intake of antioxidants through healthy eating. Major sources of oxidation damage are tobacco smoke and unprotected exposure to the sun’s ultraviolet rays.

Since free radicals are formed when the body processes calories, avoiding excessive calories may also limit the oxidation damage to your body, as well as weight gain.

By following the mostly plant-based diet recommended by the American Institute for Cancer Research, your intake of antioxidants will rise.

Most importantly, by eating a wide variety of vegetables, fruits, whole grains and beans, you will receive a wide range of antioxidants which science shows work most effectively together.

Nutrition Notes is provided by the American Institute for Cancer Research in Washington, D.C.

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