Fruits, vegetables and risk of renal cell carcinoma: a prospective study of Swedish women.

Findings of epidemiologic studies on the relationship between fruit and vegetable consumption and renal cell carcinoma (RCC) risk have been inconclusive. To study the association between fruits and vegetables and risk of RCC in a population-based prospective cohort study of Swedish women, we collected dietary information from 61,000 women age 40-76 years by a food-frequency questionnaire. During 13.4 years of follow-up 122 women developed RCC. Cox proportional hazards models were used to estimate relative risks (RR) with 95% confidence interval (CI). Women consuming 5 or more servings of fruit and vegetables daily had a relative risk of 0.59 (95% CI = 0.26-1.34) in comparison to them consuming less than once daily. When fruits and vegetables were examined separately, those who consumed more than 75 servings per month of fruits or vegetables had multivariate relative risk of 0.59 (95% CI = 0.27-1.25) and 0.60 (95% CI = 0.31-1.17) respectively, compared to those consuming 11 or less servings per month. Within the group of fruits, the strongest inverse association was observed for banana (p = 0.07 by Wald test). The risk of RCC increased monotonically with increasing intake frequencies of fruit juice (p-value for trend = 0.10). Within the group of vegetables, the strongest inverse association was observed for root vegetables (p = 0.03 by Wald test). The risk of RCC decreased with increasing consumption frequencies of white cabbage (p for trend = 0.07). Frequent consumption of salad vegetables (once or more per day) decreased the risk by 40% (RR = 0.60; 95% CI = 0.30-1.22), in comparison to no consumption. Our results suggested that high consumption of fruits and vegetables might be associated with reduced risk of RCC.