Antioxidants and Cancer Prevention

LAGRANGE, Ill.--In December 1999, the VERIS Research Summary provided anoverview of current research on vitamin E and other antioxidants in regard toselected cancers. This research suggested that antioxidants may alter cancerincidence and growth by acting as anticarcinogens. However, a dietary deficiencyof antioxidants may allow certain cancers to propagate.

Antioxidants have various roles in cancer prevention and control. Accordingto researchers, the depletion of vitamin E, vitamin C and beta-carotene affectthe development of certain cancers. In a mortality follow-up study,beta-carotene blood levels were significantly lower in lung cancer and stomachcancer cases; below-average blood levels of vitamins A and C were associatedwith stomach cancer; vitamin E levels were low in colon and stomach cancer.

Vitamin E also protected vitamin A from destruction in the body and inhibitedthe conversion of nitrites--which are present in smoked, pickled and curedfoods--into nitrosamines in the stomach (nitrosamines are cancer-causingagents). However, a combination of selenium and vitamin E had a greaterinhibiting effect than either nutrient alone.

An association between antioxidant levels and the risks of cervical, ovarianand breast cancer was also investigated. In a population-based, case-controlledstudy, frequent intakes of dark green or deep yellow vegetables and fruit juiceswere associated with a lower risk of cervical cancer. There was also an inversecorrelation between vitamin C and vitamin E intake and cervical cancer risk.

The study suggests that appropriate dietary measures can lower the rate ofcancer in humans. Conversely, individuals with a high intake of protein andnitrites and a low intake of vitamins C and E were five times more likely todevelop cancer than individuals with a high intake of vitamins C and E and a lowintake of protein and nitrites.