Antioxidants protect the body from damage that harmful molecules ,free radicals ,can cause at high levels. It is believed that this damage is a factor in the development of blood vessel disease (atherosclerosis), cancer, and other conditions.

Antioxidants , despite their name, do not prevent oxidation. Instead, they oxidize first, preventing the oxidizing agent from oxidizing compounds that are more important to proper functioning of a system, as in a cell.

Sources of free radicals:
-  By-products of normal metabolic processes that take place in the body.
-  When the body breaks down certain drugs.
-  Pollutants.

The following substances have shown positive antioxidant effects:

Generally the best sources of antioxidants are fruits and vegetables.

Vitamin A (Retinol, also synthesized by the body from beta-carotene) protects dark green, yellow and orange vegetables and fruits from solar radiation damage, and is thought to play a similar role in the human body.

Vitamin C (Ascorbic acid) is a water-soluble compound that fulfills several roles in living systems. Important sources include citrus fruits (such as oranges, sweet lime, etc.), green peppers, broccoli, green leafy vegetables, strawberries, raw cabbage and tomatoes.

Vitamin E, including Tocotrienol and Tocopherol, is fat soluble and protects lipids. Sources include wheat germ, nuts, seeds, whole grains, green leafy vegetables, vegetable oil, and fish-liver oil. Recent studies showed that some tocotrienol isomers have significant anti-oxidant properties.

Selenium have a beneficial effect in reducing the occurrence of male prostate cancer. However, the substance must be taken in measured amounts because large doses of the element can be toxic. Good food sources include fish, shellfish, red meat, grains, eggs, sunflower seeds, chicken, garlic, and brazil nuts. Vegetables can also be a good source if they are grown in selenium-rich soils, and some nutritional supplements contain a supply of selenium.

Bio-flavonoids are present in many dark berries such as pomegranate, noni, blueberries, and blackberries, as well as in certain types of tea and coffee, especially green tea. Coffee is often depleted of antioxidants due to the high-temperature roasting process.

Several food additives, including pectin, ascorbic acid (vitamin C) and tocopherol-derived compounds are used as antioxidants to help guard against food deterioration.

What are antioxidants used for?
Antioxidants are used to help treat or prevent some medical conditions, such as coronary artery disease (CAD), some cancers, macular degeneration, Alzheimer's disease, and some arthritis-related conditions.

Antioxidants safety?
Until more studies are done, you should get your antioxidants from a diet rich in fruits and vegetables rather than from supplements. No single antioxidant alone can protect the body. Most people should eat 5 to 9 servings of fruits and vegetables each day.

There is no strong evidence that beta-carotene supplements prevent CAD, and some studies have shown that they may be harmful.

Always tell your health provider if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a dietary supplement. This is especially important for women who are pregnant or breast-feeding.