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Cancer Nutrition Network for Texans

Antioxidants

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What is it?

Oxygen is essential for human life. It may seem odd then that there is so much interests in "anti-oxidants". Antioxidants are a classification of organic substances that protect cells in your body from damage by neutralizing the free radicals.

How does it work?

When the cells that form our bodies burn oxygen, one byproduct that is formed is called a free radical. Free radicals damage cell walls, cell structures and genetic material. While the body has ways to inactivate free radicals, if these become overwhelmed, accumulated damage can become irreversible and lead to diseases such as cancer, heart disease and strokes. Antioxidants play the housekeeper's role, “mopping up” free radicals before they get a chance to do harm to your body. Examples of antioxidants include vitamin E, vitamin C, vitamin A, selenium and carotenoids. Carotenoids, of which beta-carotene is the most popular, are pigments which add color to fruits and vegetables.

Is it effective?

Studies have shown that people who eat diets high in vitamin C, found mainly in citrus fruits, have lower rates of cancer of the mouth, larynx and esophagus as well as less heart disease.

A five-year study by the National Cancer Institute confirmed the beneficial effects of antioxidants. Patients who received from 1-2 times the U.S. Recommended Daily Allowance of beta-carotene, vitamin E and selenium had a reduced cancer rate of 13%. Another study the Mayo Clinic demonstrated that green tea, which contains chemicals called polyphenols, powerful antioxidants, was shown to inhibit the growth of cancer cells when taken at low levels and to kill prostate cancer cells at higher levels.

In addition, Vitamin C has been shown to reduce the rate of heart disease, as has Vitamin E, which defends against low-density lipoprotein oxidation that results in artery clogging plaque formation. A study by the American Heart Association showed that women who had the highest consumption of vitamins C and E, beta carotene and riboflavin had a 33% lower risk of heart attack and a 71% lower risk of stroke than women who ate few antioxidant containing foods.

What is the state of the science?

Unfortunately many people take large doses of these vitamins every day, even though the long-term effect of large doses of these nutrients is not known but is currently under investigation. Vitamins A and E are fat soluble, meaning that excess amounts are stored in the liver and fatty tissues creating a risk of toxicity. The best way to ensure an adequate intake of antioxidants is a balanced diet consisting of 5-8 servings of fresh fruits and vegetables per day.


Barbara Pence, Ph.D., is the Associate Vice President for Research and Associate Dean for Research and the Graduate School at Texas Tech University Health Sciences Center.

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