Dear Dietitian – What are antioxidants and what do they do?

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Published Thursday, August 26, 2021
PICT Leanne McCrate Dear Dietitian
by Leanne McCrate, RD, LD, CNSC

Dear Readers,

Most of you have probably heard of antioxidants. They're good for you, right? But what are they, exactly? "Antioxidant" is a chemistry term that simply means preventing oxidation, which is the transfer of tiny, electrically charged particles known as electrons.

Antioxidants protect us from free radicals, which damage our cells and may lead to cancer, heart disease, and Alzheimer's. Free radicals are unstable molecules that wish to become stable. In doing so, they rob another cell of an electron needed for stability. The cell that has been robbed is now susceptible to damage. Free radicals result from food digestion, everyday cellular activity, and outside sources like smoking and air pollution.

Studies on the role of antioxidants and disease prevention have produced mixed results. In the Women's Health Study, over 39,000 women took 600 IU of vitamin E or placebo every other day for ten years. At the end of the study, the rates of stroke, heart attack, and cancer were not lower among those taking vitamin E. However, there was a significant twenty-four percent reduction in death from stroke and heart attack (1).

There was another large study of beta-carotene supplementation in men who were heavy smokers. The study was aborted because there was a significant increase in lung cancer among those taking the supplement than those given the placebo (2).

Antioxidants in their natural food state may have health benefits that are not found when taking them in supplement form. A possible explanation of this is the x-factor. When consuming foods that contain antioxidants, one also gets fiber and other nutrients in that food that cannot be found in a supplement. The x-factor could be a combination of nutrients that have a health benefit or even be a factor that has not yet been identified. Remember, the science of nutrition is still in its infancy, and there is still much to be revealed.  

Listed below are particular antioxidants and their food sources:

  • Vitamin C- oranges, grapefruit, lemons, cantaloupe, kohlrabi, broccoli
  • Vitamin E- nuts & seeds
  • Beta-carotene-carrots, sweet potatoes, spinach, broccoli, winter squash, cantaloupe
  • Polyphenols- red grapes, red wine, coffee, chocolate, legumes
  • Lutein-spinach, kale, egg yolk
  • Selenium- beef, pork, turkey, fish, chicken, shellfish, nuts, seeds, soy products
  • Manganese-pineapple, nuts, beans, spinach

Remember, a diet rich in fruits and vegetables, whole grains, legumes, nuts, seeds, and lean proteins, along with a healthy body weight, is the best bet for keeping us healthy. 

Until next time, be healthy!

Dear Dietitian


  1. Lee IM, Cook NR, Gaziano JM, et al. Vitamin E in the primary prevention of cardiovascular disease and cancer:The Women's Health Study: a randomized controlled trial. JAMA. 2005; 294:56-65.
  2.  Albanes D, Heinonen OP, Taylor PR, et al. Alpha-tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. J Natl Cancer Inst. 1996; 88:1560-70.

Leanne McCrate, RD, LD, CNSC, aka Dear Dietitian, is an award-winning dietitian based in Missouri. Her mission is to educate consumers on sound, scientifically-based nutrition. Do you have a nutrition question? Email her at Dear Dietitian does not endorse any products, health programs, or diet plans. may earn an affiliate commission if you purchase products or services through links in an article. Prices, when displayed, are accurate at the time of publication but may change over time. Commissions do not influence editorial independence.

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