Antioxidants are some of the most researched organic molecules of the past few decades. This is due to their unique properties that allow them to reverse cellular damage caused by the normal processes that, ironically, keep organisms alive. Their efficacy to dramatically reduce cancer and the effects of aging, however, is still being debated. They are found in vitamin-rich foods such as fruits and vegetables.
Oxidation
Oxidation is a process that occurs during cellular respiration that results in the transfer of electrons from a substance to an oxidizing agent. This is a kind of chemical reaction often involved in combustion or rusting. In cellular respiration it creates byproducts known as free radicals, which are atoms or groups of atoms with an odd unpaired number of electrons. They can cause cellular damage and react with important cellular components such as DNA or the cell membrane. This has been known to cause cancer, aging and a number of diseases.
Function
Antioxidants, as the name suggests, are molecules that reverse the deleterious effects of oxidation. They safely interact with free radicals and terminate the chain reaction before cellular damage occurs. This protects the cells from functioning poorly or, in the more extreme circumstances, dying. Antioxidants come in many different forms of organic molecules.
Types
Although there are many enzymes--proteins that facilitate chemical reactions--within the body that scavenge free radicals, the principal micronutrient antioxidants that come from the diet are vitamin E, beta-carotene and vitamin C. Beta-carotene is a precursor to vitamin A, called retinol, which is manufactured in the body.
Vitamins
Vitamin E, or d-alpha tocopherol, is a fat-soluble vitamin, meaning that it can be dissolved in fat. It is present in nuts, seeds, vegetable and fish oil, whole grains, fortified cereals and apricots. The recommended daily allowance is 15 IU for men and 12 IU for women--an IU is equivalent to 0.667 mg. Vitamin C, or ascorbic acid, is a water-soluble vitamin found in citrus fruits and juice, green peppers, spinach, cabbage, broccoli, kale, cantaloupe, kiwi and strawberries. The recommended daily allowance is 60 mg. Beta-carotene is found in egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomatoes, cantaloupe, peaches and grains.
Considerations
There has been a lot of intense scientific investigation about whether diets rich in fruits and vegetables, and thus the antioxidants found in vitamins, can potentially protect against the development of cancer and slow the aging process. According to the National Cancer Institute, however, many of the large-scale randomized clinical trials have been inconclusive. The first large-scale trial was conducted by the Chinese Cancer Prevention Study in 1993. It found that a combination of beta-carotene, vitamin E and selenium significantly reduced incidents of gastric cancer and overall cancer in high risk Chinese men and women who were otherwise healthy. But some studies since have shown no effect, and one study on Finnish smokers actually found an increased occurrence. The relationship between vitamins in the diet and occurrences of cancer are probably too complex to lend themselves to easy answers.
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