Dairy Consumption and Total Cancer and Cancer-Specific Mortality: A Meta-Analysis of Prospective Cohort Studies

The association between dairy consumption and cancer mortality varies among studies and remains unclear. Thus, we conducted a comprehensive meta-analysis of prospective cohort studies to examine the association between dairy consumption and total cancer and cancer-specific mortality. We sought eligible studies in PubMed and Web of Science databases for all publications through March 2021, and pooled relative risks (RR) and 95% confidence intervals were calculated. We identified 34 prospective cohort studies including 3,171,186 participants and 88,545 deaths. Compared with low milk consumption, high milk consumption was associated with higher cancer mortality in females (RR:1.10; 95% CI: 1.01, 1.21) and people consuming high/whole-fat milk (fat content ≥ 3.5%) (RR:1.17; 95% CI: 1.07, 1.28). Increased risks of cancer-specific mortality were detected for liver (RR:1.13; 95% CI: 1.02, 1.26), ovarian (RR:1.32; 95% CI: 1.13, 1.55), and prostate (RR:1.23; 95% CI: 1.02, 1.48) cancers. Also, females with high consumption of fermented milk had a lower cancer mortality risk (RR:0.85; 95% CI: 0.77, 0.94). High cheese consumption was not associated with total cancer mortality, rather with higher colorectal cancer mortality (RR:1.22; 95% CI: 1.02, 1.46). There was no association between butter (RR:1.06; 95% CI: 0.70, 1.59) or total dairy product consumption (RR:0.99; 95% CI: 0.95, 1.03) and cancer mortality. Our results imply that high milk consumption, especially high/whole-fat milk, was associated with higher cancer mortality, while fermented milk consumption was associated with lower cancer mortality, and this was particularly evident in females. Consequently, further studies are warranted.