Dairy Consumption and Risks of Colorectal Cancer Incidence and Mortality: A Meta-analysis of Prospective Cohort Studies

Background: Previous studies of dairy consumption and colorectal cancer incidence have shown inconsistent results, and there was no meta-analysis of association of dairy consumption with colorectal cancer mortality. Thus, we conducted a comprehensive analysis of prospective cohort studies to investigate these associations. Methods: PubMed and Web of Science databases were searched for eligible studies published up to July 2019, and a random effects model was used to estimate pooled RR. Results: We identified 31 prospective cohort studies, which included 24,964 and 2,302 cases for colorectal cancer incidence and mortality, respectively. The pooled RR of colorectal cancer incidence for the highest versus lowest categories of total dairy consumption was 0.79 [95% confidence interval ( CI), 0.74-0.85]. For milk consumption, there was also a significant inverse association (RR, 0.81; 95% CI, 0.76-0.86). For cheese and fermented milk consumption, overall no association was found, but studies conducted in Europe showed a significant inverse association for cheese (RR, 0.87; 95% CI, 0.78-0.97) and fermented milk consumption ( RR, 0.91; 95% CI, 0.85-0.98). For colorectal cancer mortality, we found 29% lower risk of death from colorectal cancer in subjects with high dairy consumption compared with those with low intakes of dairy products (RR, 0.71; 95% CI, 0.54-0.93), but each type of dairy consumption did not show a significant association. Conclusions: High dairy consumption was associated with lower colorectal cancer incidence and mortality. Impact: Our findings suggest that high dairy consumption may be associated with lower colorectal cancer incidence and mortality, but further studies are warranted.