Diet, lung function, and lung function decline in a cohort of 2512 middle aged men

Background-A prospective cohort study of 2512 Welshmen aged 45-59 living in Caerphilly in 1979-1983 was used to investigate associations between diet and lung function. Methods-At baseline (phase I) and at five year follow up (phase II), forced expiratory volume in one second (FEV1) was measured using a McDermott spir ometer and dietary data were obtained using a semi-quantitative food freque ncy questionnaire. Results-Good lung function, indicated by high maximum FEV1 given age and he ight, was associated with high intakes of vitamin C, vitamin E, beta-carote ne, citrus fruit, apples, and the frequent consumption of fruit juices/squa shes. Lung function was inversely associated with magnesium intake but ther e was no evidence of an association with fatty fish. Following adjustment f or confounders including body mass index, smoking history, social class, ex ercise, and total energy intake, only the associations with vitamin E and a pples persisted, with lung function estimated to be 39 ml (95% confidence i nterval (CI) 9 to 69) higher for vitamin E intakes one standard deviation ( SD) apart and 138 mi higher (95% CI 58 to 218) for those eating five or mor e apples per week compared with non-consumers. Decline in lung function bet ween phases was not significantly associated with the changing intakes of a pples or vitamin E. An association between high average apple consumption a nd slow decline in lung function lost significance after adjustment for con founders. Conclusions-A strong positive association is seen between lung function and the number of apples eaten per week cross sectionally, consistent with a p rotective effect of hard fruit rather than soft/citrus fruit. The recent su ggestion that such effects are reversible was not supported by our longitud inal analysis.