Antioxidants 101 – What and Where?

Written By: Gloria Tsang, RD

Title: Founding Registered Dietitian

Alumni: University of British Columbia

Last Updated on:

Antioxidants are substances or nutrients in our foods which can prevent or slow the oxidative damage to our body. When our body cells use oxygen, they naturally produce free radicals (by-products) which can cause damage. Antioxidants act as “free radical scavengers” and hence prevent and repair damage done by these free radicals.  Health problems such as heart disease, macular degeneration, diabetes, cancer are all contributed by oxidative damage. Antioxidants may also enhance immune defense and therefore lower the risk of cancer and infection.

Most Commonly Known Antioxidants

  • Vitamin A and CarotenoidsCarrots, squash, broccoli, sweet potatoes, tomatoes, kale, collards, cantaloupe, peaches and apricots (bright-colored fruits and vegetables!)
  • Vitamin CCitrus fruits like oranges and lime etc, green peppers, broccoli, green leafy vegetables, strawberries and tomatoes
  • Vitamin ENuts & seeds, whole grains, green leafy vegetables, vegetable oil and liver oil
  • SeleniumFish & shellfish, red meat, grains, eggs, chicken and garlic

Some common phytochemicals

  • Flavonoids / polyphenols
    • soy
    • red wine
    • purple grapes or Concord grapes
    • pomegranate
    • cranberries
    • tea
  • Lycopene
    • Tomato and tomato products
    • pink grapefruit
    • watermelon
  • Lutein
    • dark green vegetables such as kale, broccoli, kiwi, brussels sprout and spinach
  • Lignan
    • flax seed
    • oatmeal
    • barley
    • rye

Vitamin-like Antioxidants

  • Coenzyme Q10 (CoQ10)
  • Glutathione

Antioxidant enzymes made by the body

  • superoxide dismutase (SOD)
  • catalase
  • glutathione peroxidase

The Bottom Line

Antioxidants are found abundant in beans, grain products, fruits and vegetables. Look for fruits with bright color – lutein in some of the yellow pigments found in corn; orange in cantaloupe, butternut squash and mango; red from lycopene in tomatoes and watermelon, and purple and blue in berries. So enjoy eating a variety of these products. It is best to obtain these antioxidants from foods instead of supplements. In addition, minimize the exposure of oxidative stress such as smoking and sunburn.


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