Antioxidants and Cancer Prevention
LAGRANGE, Ill.--In December 1999, the VERIS Research Summary provided an overview of current research on vitamin E and other antioxidants in regard to selected cancers. This research suggested that antioxidants may alter cancer incidence and growth by acting as anticarcinogens. However, a dietary deficiency of antioxidants may allow certain cancers to propagate.
Antioxidants have various roles in cancer prevention and control. According to researchers, the depletion of vitamin E, vitamin C and beta-carotene affect the development of certain cancers. In a mortality follow-up study, beta-carotene blood levels were significantly lower in lung cancer and stomach cancer cases; below-average blood levels of vitamins A and C were associated with stomach cancer; vitamin E levels were low in colon and stomach cancer.
Vitamin E also protected vitamin A from destruction in the body and inhibited the conversion of nitrites--which are present in smoked, pickled and cured foods--into nitrosamines in the stomach (nitrosamines are cancer-causing agents). However, a combination of selenium and vitamin E had a greater inhibiting effect than either nutrient alone.
An association between antioxidant levels and the risks of cervical, ovarian and breast cancer was also investigated. In a population-based, case-controlled study, frequent intakes of dark green or deep yellow vegetables and fruit juices were associated with a lower risk of cervical cancer. There was also an inverse correlation between vitamin C and vitamin E intake and cervical cancer risk.
The study suggests that appropriate dietary measures can lower the rate of cancer in humans. Conversely, individuals with a high intake of protein and nitrites and a low intake of vitamins C and E were five times more likely to develop cancer than individuals with a high intake of vitamins C and E and a low intake of protein and nitrites.