Cultured milk, yogurt, and dairy intake in relation to bladder cancer risk in a prospective study of Swedish women and men

Background: Findings from epidemiologic studies of the effect of dairy foods (mainly milk) on the risk of bladder cancer have been inconsistent. Objective: We aimed to examine the association between the intake of cultured milk and other dairy foods and the incidence of bladder cancer in a prospective, population- based cohort. Design: We prospectively followed 82 002 Swedish women and men who were cancer-free and who completed a 96-item food-frequency questionnaire in 1997. Incident cases of bladder cancer were identified in the Swedish cancer registries. Results: During a mean follow-up of 9.4 y, 485 participants (76 women and 409 men) were diagnosed with bladder cancer. Total dairy intake was not significantly associated with risk of bladder cancer [>= 7.0 servings/d compared with < 3.5 servings/d: multivariate rate ratio (RR) = 0.87; 95% CI: 0.66, 1.15; P for trend = 0.33]. However, a statistically significant inverse association was observed for the intake of cultured milk (sour milk and yogurt). The multivariate RRs for the highest category of cultured milk intake (>= 2 servings/d) compared with the lowest category (0 serving/d) were 0.62 (95% CI: 0.46, 0.85; P for trend = 0.006) in women and men combined, 0.55 (95% CI: 0.25, 1.22; P for trend = 0.06) in women, and 0.64 (95% CI: 0.46, 0.89; P for trend = 0.03) in men. The intake of milk or cheese was not associated with bladder cancer risk. Conclusion: These findings suggest that a high intake of cultured milk may lower the risk of developing bladder cancer.