When we examined specific gene-B-vitamin interactions, we observed a possible interaction between methylenetetrahydrofolate reductase -C677T and plasma B(2) on risk of all adenomas.
Almost all of seven studies of colorectal adenoma have found no association between C677T polymorphism and adenoma, but the 677TT genotype seems to be related to increased risk when folate status is poor.
Among 379 cases and 726 controls, MTHFR genotypes were not appreciably related to risk of adenoma, but a suggestive interaction (P = 0.09) was observed between MTHFR 677C-->T and alcohol intake; men with TT homozygotes who consumed 30+ g/day of alcohol had an odds ratio (OR) of 3.52 [95% confidence interval (CI), 1.41-8.78] relative to drinkers of < or =5 g/day with the CC/CT genotypes.
Smoking, folate status and the C677T MTHFR polymorphism were strong, interactive determinants of high-risk adenomas (HRAs, defined as adenomas > or =10 mm in diameter, adenomas with villous components or with severe dysplasia).