Antioxidants

Other Name(s):

free radical scavengers

General Description:

Antioxidants help prevent free radicals from damaging the body by neutralizing them.

A free radical is an atom or molecule that contains one or more unpaired electrons. These unpaired electrons want to bond to atoms or molecules and do so easily. The body is damaged during this bonding process. Individuals are exposed to many things that will create free radicals such as radiation, environmental toxins and tobacco smoke. The body also generates free radicals when it converts fat to energy.

Antioxidants come in many forms including enzymes, vitamins and minerals. Below is a partial list.

Enzymes:

• Catalase

• Coenzyme Q-10

• Glutathione peroxidase

• Methionine reductase

• Superoxide dismutase (SOD)

Vitamins:

• Beta-carotene

• Vitamin A

• Vitamin C

• Vitamin E

Minerals:

• Selenium

• Zinc

Herbs:

• Bilberry

• Ginkgo biloba

• Grape seed extract

• Green tea extract

Others:

• Anthocyanadins

• Carotenoids

• Flavonoids

• Resveratrol

Medically Valid Uses:

Antioxidants have been studied to evaluate their impact on cancer, cancer prevention, heart disease, arthritis and diseases associated with aging such as macular degeneration. Research generally supports the positive effects of antioxidants in reducing the risk of these and other diseases.

• Antioxidants, especially selenium, may reduce the incidence of some types of cancers such as lung, colorectal and prostate.

• Vitamin E has been the most effective antioxidant in reducing the risk for heart disease.

• Antioxidants have been shown to reduce the pain associated with arthritis.

• Antioxidants, especially vitamin C, vitamin E and carotenoids, may delay the onset of macular degeneration. Macular degeneration is an eye disease and a leading cause of blindness in individuals over age 65. The macula is the portion of the retina responsible for our sharpest and most acute vision.

Antioxidants interfere with these disease processes by stopping free radicals.

Unsubstantiated Claims:

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Researchers agree that antioxidants from fruits and vegetables do reduce the risk for many diseases and affect the onset of age-related illnesses. However, evidence concerning the intake of antioxidants from supplements has not been conclusive. The benefit of taking antioxidants derived from supplements varies among studies.

Dosing Format:

The following table lists some antioxidants and the recommended dietary allowance (RDA) for adults.

Some research suggests that dramatically increasing the intake of antioxidants enhances their benefit. In his book, Spontaneous Healing, Dr. Andrew Weil suggests the following schedule and doses for optimal effectiveness of antioxidants:

The above table includes measurements in micrograms (mcg), milligrams (mg) and international units (IU).

Women who are pregnant or breast-feeding should consult a physician before taking any dietary supplements.

Side Effects, Toxicity and Interactions:

The side effects of antioxidants vary, depending on the individual antioxidant.

There are no significant food or drug interactions associated with antioxidants.

Additional Information:

The interactions between certain antioxidants are important to their success in eliminating free radicals. For example, vitamin E is more effective as an antioxidant when taken with selenium. Since a single antioxidant is not as successful as multiple antioxidants in eliminating free radicals, it is best to take supplements that combine a variety of antioxidants and/or eat a diet that provides many different antioxidants.

Click here for a list of reputable Web sites with general information on nutrition.

References:

1. Murray M, and Pizzorno J. Encyclopedia of Natural Medicine. Revised 2nd Edition. Prima Publishing, Rocklin, California; 1998.

2. Balch JF, Balch P. Prescription for Nutritional Healing. 2nd Edition. Avery Publishing Group, Garden City Park, NJ;1997.

3. Barber DA, Harris SR. Oxygen free radicals and antioxidants: a review. Am Pharm. 1994;NS34(9):26-35.

4. Patterson RE, White E, Kristal AR, Neuhouser ML, Potter JD. Vitamin supplements and cancer risk: the epidemiologic evidence [see comments]. Cancer Causes Control. 1997;8(5):786-802.

5. Rimm EB, Stampfer MJ. The role of antioxidants in preventive cardiology. Curr Opin Cardiol. 1997;12(2):188-94.

6. Sangha O, Stucki G. [Vitamin E in therapy of rheumatic diseases (see comments)]. Z Rheumatol. 1998;57(4): 207-14.

7. Combs GF Jr, Clark LC, Turnbull BW. Reduction of cancer mortality and incidence by selenium supplementation. Med Klin. 1997;92 Suppl 3:42-5.

8. Jacob RA, Burri BJ. Oxidative damage and defense. Am J Clin Nutr. 1996;63(6):985S-990S.

9. Ward JA. Should antioxidant vitamins be routinely recommended for older people? Drugs Aging. 1998 Mar;12(3):169-75.

10. Jacques PF. The potential preventive effects of vitamins for cataract and age-related macular degeneration. Int J Vitam Nutr Res. 1999;69(3):198-205.

11. Weil A. Spontaneous Healing. New York: Fawcett Columbine; 1995.