Vitamin B Intake and the Risk of Colorectal Cancer: A Meta-Analysis of Prospective Cohort Studies.

OBJECTIVES

We performed this meta-analysis to estimate the association between vitamin B intake and colorectal cancer risk.

METHODS

Prospective cohort studies on vitamin B intake and colorectal cancer risk were identified by searching databases from the period of 1960 to 2016. Results from individual studies were synthetically combined using Stata 13.0 software.

RESULTS

A total of 10 prospective cohort studies including 13 data sets were included in our meta-analysis, containing 7,817 cases and 784,550 subjects. The combined relative risks (RR) of colorectal cancer for the highest vitamin B intake compared with the lowest vitamin B intake was 0.88 [95% confidence intervals (CIs): 0.77-1.02]. Dose-response meta-analysis based on five eligible studies showed that for each additional 3 and 5 mg of vitamin B intake, the risk would decrease by 11% (RR: 0.89, 95%CI: 0.81-0.98) and 17% (RR: 0.83, 95%CI: 0.71-0.97), respectively. Little evidence of publication bias was found.

CONCLUSION

This meta-analysis provides evidence of a nonsignificant decrease in colorectal cancer risk associated with the high level of vitamin B intake, but the risk in dose-response analysis is significant. However, the latter finding is based on a limited number of studies, which should be interpreted with caution.