The role of vitamin B12 and folate in carcinogenesis

The roles of vitamin B12 and folate in carcinogenesis are largely extensions of and linked to their roles in normal metabolism, particularly 1-carbon unit metabolism. A possible key area may be hypomethylation to "switch on" genes and methylation to "switch them off." Some vitamin analogues may act as antivitamins in these reactions, as may some vitamin-binding proteins. Others may act as specific delivery proteins. Using appropriate radioactive substrates and suspensions of vitamin-dependent normal and malignant cells, it may be possible to work out their positive and negative control of DNA synthesis.