Previous studies have suggested that high folate intake may afford some protection against colorectal cancer and adenomas. Smoking has been shown to increase the risk of colon cancer.
Dr Arve Ulvik, of the University of Bergen, Norway, and colleagues investigated whether smoking, folate status, and methylenetetrahydrofolate reductase (MTHFR) genotype can predict the risk of adenomatous and hyperplastic colorectal polyps.
Dr Ulvik's team determined the smoking status and red blood cell folate levels of 443 patients, aged 63-72 years. The researchers also obtained each patient's genotype for the C667T single nucleotide polymorphism of the MTHFR gene.
|There is a 3-way interaction between smoking, C677T genotype, and folate status.
|American Journal of Medical Genetics|
Smoking, folate status, and MTHFR genotype were found to be strong determinants of high-risk adenomas.
The risk of adenomas was particularly high in smokers with low folate and the CT or TT genotype of the C667T polymorphism. However, smokers with the CC genotype were particularly at risk if they had high folate levels.
Dr Ulvik concludes, "The data demonstrate the strong gene-nutrition interaction involving the C677T polymorphism of the MTHFR gene".