Dairy products intake and cancer mortality risk: a meta-analysis of 11 population-based cohort studies

Background: Dairy products are major components of daily diet and the association between consumption of dairy products and public health issues has captured great attention. In this study, we conducted a meta-analysis to investigate the association between dairy products intake and cancer mortality risk. Methods: After a literature search in PubMed and EMBASE, 11 population-based cohort studies involving 778,929 individuals were considered eligible and included in the analyses. Data were extracted and the association between dairy products intake and cancer mortality risk was estimated by calculating pooled relative risks (RRs) and corresponding 95 % confidence intervals (CIs). Sensitivity analyses and subgroup analyses based on regions, genders and dairy types were performed as well. Potential dose-response relationship was further explored by adopting the generalized least squares (GLST) method. Results: Total dairy products intake was not associated with all cancer mortality risk, with the pooled RR of 0.99 (95 % CI 0.92-1.07, p = 0.893). Subgroup analyses showed that the pooled RRs were 0.97 (95 % CI 0.92-1.03, p = 0.314) for milk, 0.88 (95 % CI 0.71-1.10, p = 0.271) for yogurt, 1.23 (95 % CI 0.94-1.61, p = 0.127) for cheese and 1.13 (95 % CI 0.89-1.44, p = 0.317) for butter in male and female, however the pooled RR was 1.50 (95 % CI 1.03-2.17, p = 0.032) for whole milk in male, which was limited to prostate cancer. Further dose-response analyses were performed and we found that increase of whole milk (serving/day) induced elevated prostate cancer mortality risk significantly, with the RR of 1.43 (95 % CI 1.13-1.81, p = 0.003). Conclusions: Total dairy products intake have no significant impact on increased all cancer mortality risk, while low total dairy intake even reduced relative risk based on the non-linear model. However, whole milk intake in men contributed to elevated prostate cancer mortality risk significantly. Furthermore, a linear dose-response relationship existed between increase of whole milk intake and increase of prostate cancer mortality risk.