Vitamin B 2 intake reduces the risk for colorectal cancer: a dose-response analysis.

Purpose: Several epidemiological studies have assessed the ability of vitamin B ₂ to prevent colorectal cancer (CRC), but the results are controversial results. We conducted a dose-response meta-analysis to investigate the association between vitamin B ₂ and CRC risk.
Methods: We searched the PubMed and EMBASE database until January 3, 2018 to identify relevant studies. The pooled relative risks (RRs) with the corresponding 95% confidence intervals (CIs) were calculated using a random-effects model or fixed-effects model. The dose-response relationship was assessed by restricted cubic splines.
Results: A total of 14 studies reporting vitamin B ₂ intake and two studies reporting blood vitamin B ₂ concentration, comprising 14,934 cases and 1593 cases, respectively, were included in the meta-analysis. Vitamin B ₂ intake was inversely associated with CRC risk (RR = 0.87; 95% CI 0.81-0.93). Similar results were found for total vitamin B ₂ intake from diet and supplements (RR = 0.86; 95% CI 0.78-0.94) and dietary vitamin B ₂ intake (RR = 0.89, 95% CI 0.82-0.98) in subgroup analyses. The dose-response model indicated a non-linear trend, and CRC risk was reduced by 10% when vitamin B ₂ intake increased to 5 mg/day. In addition, high blood concentrations of vitamin B ₂ could also reduce the CRC risk (RR = 0.74; 95% CI 0.59-0.92).
Conclusions: This dose-response analysis indicates that vitamin B ₂ intake is inversely associated with CRC risk. The inverse association may also exist between blood vitamin B ₂ concentration and CRC risk. These results suggest the importance of vitamin B ₂ intake in the prevention of CRC.