What are antioxidants?

Antioxidants are substances found naturally in food that prevent the oxidation process and act as protective agents. They protect the body from the damaging effects of free radicals (by-products of the body’s normal chemical processes). Free radicals attack the genetic material in healthy cells, which causes tumors to grow. Antioxidant research in regard to the role of antioxidants and cancer prevention continues to grow and new beneficial components of food are still yet to be discovered. Reinforced by current research, the message remains that antioxidants obtained from food sources, including fruits, vegetables and whole grains, are potentially active in disease risk reduction and can be beneficial to human health.

Antioxidants include:

–   Vitamin C (ascorbic acid)
Vitamin C may protect against cancer of the mouth, stomach, and esophagus and may also reduce the risk of developing cancers of the rectum, pancreas, and cervix. Also known as ascorbic acid, vitamin C may provide protection against breast and lung cancer.

The following foods are good sources of vitamin C:

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  • one medium orange - 69 mg
  • 1 cup orange juice - 124 mg
  • 1 medium raw green pepper - 106 mg
  • 1 cup raw strawberries - 81 mg
  • 1 cup cubed papaya - 86 mg
  • 1 medium raw red pepper - 226 mg
  • 1/2 cup cooked broccoli - 58 mg

The recommended dietary allowance (RDA) for vitamin C has recently been increased to 75 milligrams per day for women and 90 milligrams per day for men. If you smoke cigarettes, it is recommended to increase your intake of vitamin C to 100 milligrams per day.

–   Beta carotene
Beta carotene, also known as provitamin A, may help decrease the risk of developing cancer. This nutrient may prevent certain cancers by enhancing the white blood cells in your immune system. White blood cells work to block cell-damaging free radicals.

Good sources of beta carotene are dark green leafy and yellow-orange fruits and vegetables. In the body, beta carotene is converted to vitamin A. Eating foods rich in beta carotene is recommended to possibly decrease the risk of developing stomach, lung, prostate, breast, and head and neck cancer. However, more research is needed before a definite recommendation on beta carotene consumption can be made. Overdosing on beta carotene is not recommended. Large doses can cause the skin to turn a yellow-orange colour, a condition called carotenosis. High intakes of beta carotene in supplement form may actually cause lung cancer in people at risk, such as smokers, and birth defects in your baby if you are pregnant.

While there is a recommended dietary allowance for vitamin A, there is not one for beta carotene. Examples of some foods high in beta carotene include the following:

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  • carrots
  • squash
  • spinach
  • sweet potatoes  

–   Vitamin E
Vitamin E is a vitamin that helps to build normal and red blood cells, as well as working as an antioxidant. Research is finding evidence that vitamin E may protect against prostate and colorectal cancer. The recommended dietary allowance for vitamin E is 15 milligrams per day. The adult upper limit for vitamin E is 1,000 milligrams per day. Good sources of vitamin E include the following:

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  • 1 tablespoon sunflower oil - 6.9 mg
  • 30g sunflower seeds - 14 mg
  • 30g hazelnuts - 4.3 mg
  • 30g peanuts - 2.1 mg
  • 3/4 cup bran cereal - 5.1 mg
  • 1 slice whole wheat bread - .23 mg
  • 30g wheat germ - 5.1 mg

Many sources of vitamin E are high in fat therefore a synthetic form of a vitamin E is available as a supplement. Vitamin E supplementation is probably not needed for most individuals because vitamin E is a fat-soluble vitamin and is stored in our bodies. Very high doses of vitamin E can also interfere with the way other fat-soluble vitamins work. Large doses of vitamin E from supplements are not recommended for people taking blood thinners and some other medications, as the vitamin can interfere with the action of the medication. To make sure you are meeting your needs, eat a varied diet that includes whole-wheat breads and cereals and keep in mind the types of fats that are healthful: mono- and polyunsaturated fats.

There is no recommended dietary allowance for antioxidants. Eat a variety of foods, including plenty of fruits and vegetables, to ensure you are getting adequate amounts in your diet.

Good sources of antioxidants