Herb Blurb: Antioxidants
What is an antioxidant?
What does the research say?
What should I recommend?
In this month's Herb Blurb we will explore these questions. Information for this column was
obtained from an excellent review article in the Journal of the American Dietetic Association, and an article in Support Line.
What is an antioxidant?
Antioxidants exist as vitamins, minerals, and other compounds in foods. They are capable of neutralizing harmful substances called free radicals which damage cells and may contribute to cardiovascular disease and cancer. Oxidative damage can occur via ultraviolet light, radiation, smoking, dietary lipids, environmental pollutants, alcohol, injury, aging, strenuous exercise, and chronic disease. No one is immune to oxidative damage, but antioxidants can help slow down or prevent the oxidation process, and thus help prevent or repair damage done to your body's cells by oxygen.
Antioxidant Nutrients and Phytochemicals
Nutrients: Ascorbic Acid (Vitamin C), Vitamin E, Selenium, Magnesium, Zinc, Copper, Retinoids, Glutathione.
Phytochemicals: Bioflavonoids, Terpenoids, Tannins, Organosulfur compounds, Indoles, Carotenoids (found in broccoli, oranges, cantaloupe, tomatoes and many other fruits and vegetables), Lignans.
Antioxidants added to foods: BHA, BHT, Propyl gallate.
Other antioxidants: Coenzyme Q, Uric acid, alpha-lipoic acid, Melatonin, Pycnogenol, Grape seed extract.
What does the research say?
Epidemiological studies suggested that high blood concentrations of antioxidant vitamins or dietary intake of antioxidants could protect against cancer and cardiovascular disease. However, two recent studies that were conducted in the United States and Finland found that heavy smokers who took high-dose beta carotene supplements had higher rates of lung cancer. In another recent study researchers found that vitamins A and E proved damaging to mice with brain tumors because they appeared to protect cancer cells.
On the other side of the issue, researchers at the University of Colorado Health Sciences Center use beta carotene and vitamins E and C as part of the standard therapy for cancer patients. They cite studies which demonstrate that vitamins E and C and carotenoids improve immune response, aid in cell differentiation, and suppress tumor growth. Also, there are lab studies that show that antioxidants enhance the standard cancer treatment of radiation and chemotherapy.
Should we all be taking antioxidant supplements ?
Currently there is not enough evidence to support widespread use of antioxidant supplements. Human clinical trials are needed, because so far much of the evidence about the cancer-preventive role of vitamins and minerals is based on laboratory cell culture studies and animal models.
Bottom line
- Get vitamins and minerals from food sources instead of from supplements.
- Eat 5 or more servings of fruits and vegetables each day.
- Eat a grain based diet and limit meat.
- A one-a-day type multivitamin/mineral supplement is okay, but avoid large doses of a single agent.
References
1. Stahl, P. The antioxidant conundrum: two recent studies point in different directions. Journal of the American Dietetic Association 2000; 100: 510.
2. Thomson, CA. Antioxidants and Cancer. Support Line 2000; 22: 3-11.
Cynthia Boock, MS, RD
Oncology and Bone Marrow Transplant Nutrition Specialist
Froedtert and Medical College Cancer Center
Article Created: 2000-07-27
Article Updated: 2000-07-27
Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.
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