Does daily intake of green-yellow vegetables reduce the risk of cancer in man?
A cohort study, still in progress, of 265 118 adults aged 40 and above in 29 health centre districts in Japan, was begun in the autumn of 1965; it has shown that daily consumption of green-yellow vegetables significantly reduces the risk of cancers at all sites and of cancers at selected sites such as stomach and lung. The risk was seen to rise steadily with decreased intake of green-yellow vegetables. Mantel-extension chi tests on (1) crude, (2) age-standardized, (3) age-smoking-standardized, (4) age-meat-intake-standardized, and (5) age-social-class-standardized mortality rates for cancers at all sites and cancers of stomach and lung by frequency of green-yellow vegetable intake revealed a significant association and suggested a possible beneficial effect of beta-carotene intake in preventing major cancers in man. Successful intervention by such means appears to be attainable, since a greater than 25% decrease in mortality from stomach cancer was seen during the first five years in g
