Antioxidants are substances are guards against cancer causing molecules known as free radicals. Antioxidants interact with and stabilize free radicals, preventing free radical damage. Examples of antioxidants include beta-carotene, lycopene, vitamins C, E, and A, and other substances.
There is now scientific evidence from chemical, cell culture, and animal studies indicating that antioxidants can slow or possibly prevent cancer. However, information from recent clinical trials is less clear. In recent years, large scale, randomized clinical trials have reached inconsistent conclusions.
Five large scale clinical trials published in the 1990s reached differing conclusions about the effect of antioxidants on cancer. The studies examined the effect of beta carotene and other antioxidants on cancer in different patient groups. However, beta carotene appeared to have different effects depending upon the patient population.
From their results, they concluded that:
- a combination of beta carotene, vitamin E, and selenium significantly reduced incidence of both gastric cancer and cancer overall.
- Lung cancer rates increased significantly with beta- carotene and were not affected by vitamin E.
- A possible increase in lung cancer associated with antioxidants.
- There were no change in cancer rates associated with beta carotene and aspirin taken by U.S male physicians
- Among women age 45 years or older, there was no benefit or harm from beta carotene supplementation.
Antioxidants fight free radicals (molecules with incomplete electron shells which make them more chemically reactive than those with complete electron shells.) Tobacco smoke and radiation can also lead to free radical formation. The most common form of free radicals is oxygen, which steals electrons from other molecules when it is radicalized (electrically charged), causing damage to the DNA and other molecules. Long term damage may become irreversible therefore leading to cancer. Antioxidants neutralize electrical charge and prevent the free radicals from taking electrons from other molecules.
Antioxidants can be found in fruits, vegetables, nuts, grains and some meats, poultry and fish.
Here are a list of foods where you can find antioxidants:
• Beta-carotene is found in many foods that are orange in colour, including sweet potatoes, carrots, cantaloupe, squash, apricots, pumpkin, and mangos. Some green, leafy vegetables, including collard greens, spinach, and kale, are also rich in beta-carotene.
• Lutein, best known for its association with healthy eyes, is abundant in green, leafy vegetables such as collard greens, spinach, and kale.
• Lycopene is a potent antioxidant found in tomatoes, watermelon, guava, papaya, apricots, pink grapefruit, blood oranges, and other foods. Estimates suggest 85 percent of American dietary intake of lycopene comes from tomatoes and tomato products.
• Selenium is a mineral, not an antioxidant nutrient. However, it is a component of antioxidant enzymes. Plant foods like rice and wheat are the major dietary sources of selenium in most countries. The amount of selenium in soil, which varies by region, determines the amount of selenium in the foods grown in that soil. Animals that eat grains or plants grown in selenium-rich soil have higher levels of selenium in their muscle. In the United States, meats and bread are common sources of dietary selenium. Brazil nuts also contain large quantities of selenium.
• Vitamin A is found in three main forms: retinol (Vitamin A1), 3,4-didehydroretinol (Vitamin A2), and 3-hydroxy-retinol (Vitamin A3). Foods rich in vitamin A include liver, sweet potatoes, carrots, milk, egg yolks, and mozzarella cheese.
• Vitamin C is also called ascorbic acid, and can be found in high abundance in many fruits and vegetables and is also found in cereals, beef, poultry, and fish.
• Vitamin E, also known as alpha-tocopherol, is found in almonds, in many oils including wheat germ, safflower, corn, and soybean oils, and is also found in mangos, nuts, broccoli, and other foods.
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