RED-CELL AND PLASMA FOLATE, FOLATE CONSUMPTION, AND THE RISK OF COLORECTAL ADENOMATOUS POLYPS

Epidemiological and experimental evidence suggests that dietary folate may protect against colorectal carcinogenesis, The epidemiological re lationship between a biochemical measure of folate status and colorect al neoplasia in a sizeable and generally healthy population does not y et appear to have been reported, We conducted a case-control study of the relationships among red tell folate, plasma folate, folate intake, and adenomatous polyps, intermediate markers for colorectal cancer, D uring 1991-1993, fasting blood samples were assayed and dietary and no ndietary risk factor questionnaires were administered to men and women ages 50-75 years who had a free sigmoidoscopy at a health maintenance organization, We analyzed data from 682 subjects (332 cases and 350 c ontrols), controlling for potential confounding by sex, age, sigmoidos copy date, and clinic, For red cell folate levels 160 ng/ml (363 nmol/ liter) or more, compared to lower levels, the odds ratio was 0.76 [95% confidence interval (CI) = 0.53-1.08], For men, the corresponding odd s ratio was 0.53 (CI = 0.32-0.87); far women, it was 1.16 (CI = 0.67-2 .00), Results were essentially unchanged when adjusted for levels of b lood nutrients and other potential confounding variables, Plasma folat e and folate intake results were similar to red cell folate results, b ut the associations with polyps were weaker, Results are consistent wi th a protective effect of red cell folate concentration against the de velopment of colorectal polyps, at least in men, A folate effect may d epend on sex-specific interactions with other nutritional or physiolog ical factors.