Assessments of the relation between
folate intake and
ovarian cancer risk have been limited and inconsistent. Therefore, the authors prospectively examined the association of dietary and supplemental intakes of
folate,
methionine, and
vitamin B(6) with
ovarian cancer risk among 80,254 Nurses' Health Study participants. Beginning in 1976, women completed biennial questionnaires assessing
ovarian cancer risk factors; starting in 1980, food frequency questionnaires were administered every 2-4 years. During 22 years of follow-up (1980-2002), the authors confirmed 481 incident
epithelial ovarian cancers. There were no associations between total
folate (top quintile vs. bottom: relative risk (RR) = 1.21, 95% confidence interval (CI): 0.92, 1.60),
methionine (RR = 1.00, 95% CI: 0.76, 1.33), dietary
vitamin B(6) (RR = 1.09, 95% CI: 0.81, 1.47), or total
vitamin B(6) (RR = 1.13, 95% CI: 0.85, 1.51) intake and
ovarian cancer risk. Higher dietary
folate was associated with a modestly decreased risk after exclusion of cases diagnosed during the 4 follow-up years after dietary assessment (RR = 0.66, 95% CI: 0.43, 1.03) and for the serous subtype (RR = 0.51, 95% CI: 0.31, 0.84). Results did not vary by alcohol intake, multivitamin use, menopausal status, or
oral contraceptive use. There was little evidence that
folate,
methionine, and
vitamin B(6) are important in
ovarian cancer risk, although dietary
folate was inversely associated with risk in some analyses.