Folate and colorectal neoplasia: relation between plasma and dietary markers of folate and adenoma recurrence

Background: The results of epidemiologic studies indicate that higher intakes or blood concentrations of folate are associated with a lower risk of colorectal neoplasia; however, only one study assessed the role of homocysteine. Objective: We assessed the relation between biochemical and dietary markers of folate status and colorectal adenoma recurrence. Design: Analyses were conducted in 1014 men and women aged 40 – 80 y who had undergone removal of all colorectal polyps. Diet and supplement use were ascertained through a food-frequency questionnaire administered at study entry. Blood collected at baseline was used to measure plasma folate and homocysteine concentrations. Unconditional logistic regression was used to assess the odds of recurrence associated with the intakes of folate, methionine, and vitamins B-6 and B-12 and with plasma folate and homocysteine. Results: Relative to subjects in the highest quartile of plasma homocysteine, those in the lowest quartile had an odds ratio (OR) of adenoma recurrence of 0.69 (95% CI: 0.47, 1.02; P for trend 0.02) after adjustment for confounding factors. Lower odds of recurrence were shown for higher plasma folate (OR: 0.66; 95% CI: 0.46, 0.97) and higher total intakes (dietary plus supplemental) of folate (OR: 0.61; 0.42, 0.89) and vitamin B-6 (OR: 0.65; 0.45, 0.94). Slightly weaker and nonsignificant associations were shown for dietary folate, methionine, and total vitamin B-12. Conclusions: A lower recurrence of colorectal adenomas was shown in subjects with higher intakes and plasma concentrations of folate. Additional markers involved in folate metabolism, including lower homocysteine and higher vitamin B-6 intake, were also associated with lower odds of recurrence. Am J Clin Nutr2004;79: 691–7.