International Journal of Epidemiology 2003;32:64–66

Much attention has recently been paid to a possible protective effect of folate in colorectal carcinogenesis. High dietary intake of folate and high levels of plasma or serum folate have been asso-ciated with decreased risk of colorectal cancer and adenomas.1,2 Methylenetetrahydrofolate reductase (MTHFR) plays a pivotal role in folate metabolism, and MTHFR C677T polymorphism determines the activity of the enzyme.3 The MTHFR mutant homozygous TT genotype was shown to be associated with a decreased risk of colorectal cancer among those with high folate intake.1,2 On the other hand, studies of colorectal adenomas reported an increased risk associated with the MTHFR TT genotype when folate intake was low and when red blood cell (RBC) or plasma folate levels were low.4–6 Previously, we reported that the MTHFR polymorphism was unrelated to colorectal adenoma but there was a small increase in risk for the combination of TT genotype and high alcohol consumption.7 In this study, we examined the association between plasma folate levels and colorectal adenomas by MTHFR genotype in an Asian population. Methods The study subjects were men aged 47–55 years who received a pre-retirement health examination at the Self Defense Force