Sajal Kumar Jha, Roopa Karki, Amitava Ghosh
ABSTRACT Cancer has a complex etiology with multiple risk factors that involve the interplay between genetic and environmental influences. Epidemiological studies show that a high intake of antioxidant-rich foods is inversely related to cancer risk. Among a number of mechanistic hypotheses, diet-derived antioxidants have been proposed to contribute to explain these findings. Antioxidants protect against oncogenic transformation by radiation and free radical– producing anticancer drugs in experimental systems. Antioxidants do reduce the painful side effects of radiation and chemotherapy, thus supporting the beneficial effects of antioxidants in protecting normal cells during treatment and acting as adjuvants in the treatment of certain cancers. The effect of antioxidants on tumor cell growth, differentiation and apoptosis have been studied in cell culture models, transplanted tumors in syngeneic animals and in athymic mice, and in patients with certain tumors. These studies have revealed that vitamins, when used individually, can induce apoptosis selectively in cancer cells within certain dose ranges, or can inhibit or stimulate the growth of cancer cells, depending on the dose. Antioxidants nutrients such as vitamin E, vitamin C, vitamin A, and Beta- carotene are involved in detoxification of the Reactive oxygen species. Vitamin E, A, and Beta- carotene are lipophilic antioxidants whereas vitamin C is hydrophilic antioxidant. Vitamin E function as a free radical chain breaker particularly it interferes with the propagation step of lipid peroxidation. The vitamin A and Beta-carotene have actions by quenching both singlet oxygen and other free radicals generated by photochemical reactions. Key Words: Cancer; antioxidants, chemotherapy, vitamins; nutrients; free radicals.