Anti-oxidant is basically a molecule that prevents oxidation of other molecules.The role of antioxidants in cancer prevention. Oxidation is a type of chemical reaction in which there is loss of electrons and free radicals are produced as a result. The free radicals cause chain reaction and when this chain reaction occurs within a cell, it results in cell damage. Antioxidants prevent this chain reaction by terminating the free radicals and thus inhibit oxidation reactions. There are two types of antioxidants- endogenous & exogenous antioxidants. Endogenous antioxidants are used by the body partially in order to neutralize the free radicals. On the other hand exogenous antioxidants are obtained by the body through diet; primarily the sources are vegetables and grains. Lycopene, beta-carotene, vitamins A, C, and E are examples of exogenous antioxidants.
Role of antioxidants in cancer prevention
Free radicals are the source of cancer development. Laboratory researches say that chain reaction of free radicals is inhibited by exogenous antioxidants. Taking dietary supplements that consists of exogenous antioxidants can lower the risk of cancer development. Since white cell growth result in cancer development, which occurs due to chain reaction, exogenous antioxidants suppress these free radicals thus preventing cancer. But most studies and observations gave mixed results whether dietary supplements can lower the risk of cancer in humans. It depends on total diagnosis of an individual for proper outcomes of the advantages of these antioxidants because some of the results showed that patients having increased level of antioxidants are prone to cancer.
Example, some trials were conducted with people suffering from esophageal cancer and gastric cancer showed that, after intake of dietary supplements of beta-carotene, lycopene, alpha-tocopherol and selenium daily for 2-3 yrs, risk of gastric cancer was reduced but people suffering with esophageal cancer remained unaffected. This proved that antioxidants are good for cancer prevention but cannot reduce the risk of all types of cancers.
Research with alpha-tocopherol and beta-carotene supplements were made to test whether they lower the risk of lung cancer or not. Participants who were smokers took beta-carotene for 5to 6yrs showed reduction in lung cancer in contrast to those who took alpha-tocopherol showed no effect in cancer reduction. On the other hand results showed no effect of these supplements in kidney, pancreatic, renal cell cancers.
Some results also showed that consumption of antioxidants may interfere with the chemo as well as radiation therapy of cancer treatment. Chemotherapy and radiation therapy generates free radicals, which are used to inhibit the multiplication of cancer cells. It is known that antioxidants inhibit free radical reactions therefore; it might affect the therapeutic effects of chemo and radiation therapy.
Major antioxidant supplements used for cancer treatment
Grape-seed extract, selenium, resaveratrol-120 are some of the free radical scavenging anti oxidants that help in cancer prevention. Minerals like vitamin-E and vitamin A-40 are cancer-fighting supplements. They kill the cancerous cells while helping the healthy cells. These substances have the ability to act as pro-oxidants as well as antioxidants depending whether it is a malignant tumor or a healthy cell. For healthy cells, they act as antioxidants while for tumors the act like pro-oxidants.