What's So Special About Antioxidants?

Can you explain exactly what antioxidants are and why they’re so important?

– March 13, 2009

Antioxidants are micronutrients that protect tissues in the body. They do this by blocking harmful chemical reactions caused by oxidation, which is the destructive effect of oxygen (and other oxidizing agents) on the molecular components of our cells. Just as oxygen can cause metals to rust and corrode, it can pull electrons from organic molecules rendering them defective and useless. Also to be reckoned with are free radicals, electronically unstable atoms or molecules generated in the course of normal metabolism that also strip electrons from other molecules, causing chain reactions of oxidative damage. Cumulative damage of this sort probably accounts for many of the degenerative changes of aging and for a lot of age-related disease.

Antioxidants block oxidation reactions and offer protection to the membranes and other parts of cells. Vitamins C and E are capable of "quenching" free radicals by donating electrons to them. Other micronutrients that act as antioxidants are the mineral selenium and pigments called carotenoids. These include beta-carotene in orange and yellow fruits and vegetables; lycopene in tomatoes, watermelon, papaya and pink grapefruit; anthocyanins in blueberries and other blue and purple fruits and vegetables; and lutein, zeaxanthin and other carotenoids found in carrots and leafy greens. Green tea provides important antioxidants called catechins, and red wine contains resveratrol, an antioxidant from the skin of grapes. Chocolate contains similar compounds (polyphenols) to those in red wine and green tea.

We need dietary antioxidants every day. As insurance against any shortage, I recommend taking a daily supplement to give you a steady supply of these protective compounds. My general antioxidant recommendation includes the following:

  • Vitamin C: 250 milligrams (mg). If I feel I need extra, such as during a cold or environmental exposures while traveling, I take a dose of vitamin C with breakfast and dinner, or before bed. Plain ascorbic acid is fine, but may irritate a sensitive stomach, so take it with food or look for a buffered form, which is usually found in combination products.
  • Vitamin E: 400 International Units (IU) of mixed natural tocopherols, or at least 80 mg of mixed tocopherol and tocotrienols. Since vitamin E is fat soluble, it must be taken with food to be absorbed. Always choose natural vitamin E (d-alpha tocopherol with mixed tocopherols) and avoid the synthetic form (dl-alpha-tocopherol). The best brands will also include mixed tocotrienols, the other components of natural vitamin E (I take vitamin E at lunch or dinner).
  • Selenium: 200 micrograms a day. Selenium is a trace mineral with antioxidant and anticancer properties. Selenium and vitamin E facilitate each other’s absorption, so take them together. Doses above 400 micrograms a day may not be healthy.
  • Vitamin A or mixed carotenoids: 15,000 IUs a day. I recommend using natural forms of mixed carotenoids, such as alpha- and gamma-carotene along with beta-carotene, which is easily found in health food stores. Read the label to make sure a supplement gives you lycopene, the red pigment in tomatoes that helps prevent prostate cancer, and lutein, which protects against cataracts and macular degeneration. Better brands will include other important carotenoids like astaxanthin, zeaxanthin, phytoene and phytofluene.

Be sure to take supplements with meals to enhance absorption and reduce the risk of stomach upset.

Andrew Weil, M.D.


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