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. Author manuscript; available in PMC: 2016 May 1.
Published in final edited form as: Gastroenterology. 2015 Jan 6;148(6):1244–1260.e16. doi: 10.1053/j.gastro.2014.12.035

Figure 3. Folate, methionine and other B vitamins in DNA methylation and synthesis.

Figure 3

Folate from dietary intake, supplement use and synthesis by gut bacteria is converted to its predominant circulating form, 5-methyl tetrahydrofolate (THF), which can be metabolized by methionine synthase (MS) to form methionine from homocysteine. Vitamin B6 and B12 are also critical cofactors in DNA methylation and synthesis. Dysregulated DNA methylation and DNA synthesis contribute to colorectal carcinogenesis. Abbreviations: DNMT, DNA methyltransferase; MAT, S-adenosylmethonine synthase; SAH, S-adenosylhomocysteine; TS, thymidylate synthase; VDRE, vitamin D response element.