A large scale cohort study on cancer risks by diet--with special reference to the risk reducing effects of green-yellow vegetable consumption.

Using materials obtained in a large scale cohort study of 265,118 adults in Japan from 1966 to 1982, effects of diet and nutrition on cancer mortality were reviewed. Daily consumption of green-yellow vegetables (GYV) rich in beta-carotene, vitamin C, calcium, and dietary fiber was observed to lower risks for selected cancers such as lung, stomach, prostate, and cervix. The risk reducing effect appeared more striking in cigarette smokers. Risks for cancer of the stomach in males and females and cancer of the breast in females were observed to be lower with the increase in frequency of soybean paste soup consumption which frequently contains GYV. In daily meat consumers risks were higher for cancer of the lung in both sexes and for cancer of the breast in females. The habit of cigarette smoking was found to confound the apparently elevated risk in daily meat consumers for lung cancer. For breast cancer daily smoking interacted with daily meat consumption in raising the risk. The extent of risk elevation by daily meat consumption was limited when GYV was taken daily. Those who do not consume GYV daily with habits of daily smoking, daily drinking and daily meat intake were found to carry the highest risks for cancer of all sites and for cancers of selected sites such as the mouth and pharynx, esophagus, stomach, liver, larynx, lung, and urinary bladder. When GYV were consumed daily, considerably lower risk was observed for each of these cancers, even if other habits remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)