Antioxidants - Part 1

Apple Valley, CA
760-242-1234

What are antioxidants?

Antioxidants are vitamins and minerals that are believed to counter the harmful effects of by-products produced during normal metabolic processes, such as oxidation. (Oxidation simply refers to the addition of oxygen during a chemical process or reaction.)

The body requires oxygen in order to burn (metabolize) energy. Ironically, oxygen also produces toxic effects, and oxidation can alter or even destroy many substances that are found in foods and the body For example, fats (lipids) turn rancid in the presence of oxygen. Peroxides such as hydrogen peroxide — substances that are particularly rich in oxygen — are especially damaging to fat cells and other tissues.

Good sources of antioxidants

All plant foods and certain animal products contain varying amounts of antioxidants. Particularly good sources include:

Foods rich in vitamin A or its beta carotene precursor, including: green and deep yellow or orange vegetables such as broccoli and carrots; deep yellow or orange fruits such as apricots and cantaloupe; organ meats such as liver; fortified margarine; butter and other dairy products.
Foods rich in vitamin C, including: citrus fruits and juices, tomatoes, berries, cabbage, broccoli, green or red peppers, and melons.
Foods rich in vitamin E, including: wheat germ, vegetable oils, poultry and seafood, eggs, dried beans and other legumes, whole grains such as oatmeal and brown rice, and fortified margarine and cereals.
Foods rich in selenium, including: chicken, seafood, cold-water fish, egg yolks, whole-grain cereals and breads, mushrooms, onions, garlic, milk and cheese, nuts, and beef, pork, and other meats.

In addition, the process of metabolizing oxygen gives off unstable molecules called free radicals. These molecules are also produced in the body by exposure to sunlight, x-rays, and pollutants such as tobacco smoke, lead, ozone, and car exhaust.

They are often described as chemical renegades or outlaws because they can travel freely through the body wreaking havoc. They kill some cells and destroy the protective outer membranes of others. If a free

Foods rich in selenium and vitamins A, C, and E are particularly good sources of antioxidants.

radical gains access to the cell's interior, it can damage its genetic (DNA) code that controls cell reproduction. If the DNA is altered, the cell either cannot reproduce itself, or an abnormal cell is formed.

Many plants produce antioxidants as part of their natural protective mechanism. Thus, a diet that is rich in plant food is likely to provide a variety of antioxidants. Several essential vitamins and minerals have strong antioxidant properties. These include selenium, a trace mineral; beta carotene, a precursor of vitamin A; and vitamins A, C, and E. Many food additives that prevent rancidity and darkening are antioxidants; common examples include BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), and lecithin.

Why are antioxidants important to nutrition?

Antioxidants protect against the toxic effects of oxygen and by-products of oxygen metabolism, such as oxygen-free radicals. Although much remains to be learned about the damaging effects of free radicals, some nutrition scientists theorize that these molecules may play an instrumental role in many diseases, including cancer, hardening of the arteries (atherosclerosis), Alzheimer's disease, cataracts, arthritis, and numerous other degenerative disorders. Since antioxidants help neutralize free radicals, some researchers believe that these substances may be instrumental in preventing many diseases.

In addition, there is considerable speculation that antioxidants may fight off or delay much of the deterioration that occurs with normal aging. Again, the specific mechanism is unknown, but researchers theorize that many of the changes that occur with aging are due to the adverse effects of oxidation and free radicals.

Recently, there have been a flurry of scientific reports outlining possible benefits of antioxidants. Although more

study is needed to verify these findings, initial results indicate that antioxidants may play an important role in both the prevention and treatment of diseases, including the following:

Heart disease. Some researchers theorize that the oxidation of the so-called "bad" LDL cholesterol damages the artery walls and promotes development of atherosclerosis, the accumulation of fatty deposits in the coronary and other arteries. A recent World Health Organization study correlated low blood levels of two major antioxidants — vitamin E and selenium — with an increased incidence of atherosclerosis and heart attacks. A 10-year study at Harvard Medical School involving 22,000 physicians found that those taking beta carotene supplements had a 50 percent reduction in heart attacks and strokes, compared to doctors taking a placebo. Other studies have found that administering antioxidants such as vitamin E, selenium, and magnesium at the time of a heart attack minimizes heart damage.

Cancer. Although it has not been proved that antioxidants prevent cancer, a number of population (epidemiological) studies show that people whose diets are rich in antioxidants, especially beta carotene and vitamin E, have a reduced risk of cancers of the lung, prostate, colon, cervix, and breast. The protective effect appears to be particularly strong among people who smoke or are exposed to high levels of environmental pollutants that are associated with free radicals. According to an American Cancer Society report, smokers whose diet is high in beta carotene have fewer lung and oral cancers than smokers whose diet is low in these substances. Laboratory studies indicate that the cancer-causing effects of radiation may be reduced by pretreating with vitamin E. A 10-year study in Finland involving 21,000 men and 15,000 women found that persons with high blood levels of vitamin E developed fewer cancers than those with low vitamin E levels.

This article was last reviewed December 2, 2005 by Dr. James Krider.
Reproduced in part with permission of Home Health Handbook.

Printer Friendly Page

Return to Nutrition