Repeated measurements of vegetables, fruits, beta-carotene, and vitamins C and E in relation to lung cancer - The Zutphen study

The authors studied the intake of vegetables, fruits, p-carotene, and vitamins C and E in relation to the incidence of lung cancer. For 561 men from the town of Zutphen, the Netherlands, dietary history information was obtained in 1960, 1965, and 1970. During 1971-1990, 54 new cases of lung cancer were identified. The data were analyzed using Cox proportional hazard analyses, adjusting for age, pack-years of cigarettes, and energy intake. No relation between intake of vitamin E and lung cancer risk was seen. For vitamin C intake, the results pointed to an inverse association, although not entirely consistently. Furthermore, it was observed that participants with low stable intakes (i.e., low in 1960, 1965, and 1970) of vegetables, fruits, and beta-carotene experienced more than twofold increased relative risks of lung cancer than those with high stable intakes. For participants with low average intakes, relative risks were much tower and not statistically significant. The authors conclude that there is no apparent relation of vitamin E to lung cancer risk; however, for p-carotene, vitamin C, vegetables, and fruit, most studies, including the present one, suggest weak inverse associations. The use of repeated intake measurements to select subgroups with stable, highly contrasting intakes may be a promising approach for studying diet-cancer relations.