Dear Dietitian: Antioxidants
Most of you have probably heard of antioxidants and that they are good for you, but what are they exactly? Antioxidant is a chemistry term that simply means prevention of oxidation, which is the transfer of tiny, electrically charged particles known as electrons.
Antioxidants protect us from free radicals, which damage our cells and lead to diseases such as cancer, heart disease, and Alzheimer's. Free radicals result from food digestion, everyday cellular activity, and outside sources such as smoking and air pollution. 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.
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 no lower among those taking vitamin E than those who took the placebo. 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 had to be stopped early because there was a significant increase in lung cancer among those taking the supplement versus those taking 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 the 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 a lot that hasn't been figured out yet.
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
What we do know is that a diet rich in fruits and vegetables, whole grains, legumes, nuts, seeds, and lean proteins, along with a healthy body weight are our best bet for keeping us healthy.
Good health to you!
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 the consumer on sound, scientifically-based nutrition. Do you have a nutrition question? Email her at email@example.com.