VITAMIN B12 AND COLORECTAL CANCER: FRIEND OR FOE? A NARRATIVE REVIEW OF AVAILABLE EVIDENCE
Purpose: To review the potential relationship between vitamin B12 and colorectal cancer, with particular emphasis on its involvement in one-carbon metabolism and epigenetic regulation.Methods: This narrative review summarises current evidence on the biological mechanisms and epidemiological associations linking vitamin B12 status with colorectal cancer risk.Results: Available evidence indicates a biologically plausible but epidemiologically inconsistent relationship between vitamin B12 and colorectal cancer. Studies assessing dietary intake frequently report an inverse association, particularly for rectal cancer, whereas analyses of circulating vitamin B12 concentrations yield heterogeneous, and often conflicting findings.Conclusion: Vitamin B12 does not act as an isolated protective factor but as part of a complex metabolic and nutritional system. Although its potential protective role in colorectal carcinogenesis is biologically based, it remains insufficiently confirmed, emphasising the need for further integrated research.