Lack of Effects of Dietary Folate Intake on Risk of Breast Cancer: An Updated Meta-analysis of Prospective Studies

Background: Epidemiological findings are controversial relating to the relationship between dietary folateintake and the risk of breast cancer. We therefore conducted a meta-analysis of prospective cohort studies toclarify this association. Materials and
Methods: PUBMED, EMBASE, and MEDLINE databases were searchedfor all relevant literature published in English from January 1, 1966 to August 2013. Summary relative risk(RR) and 95% confidence intervals (CIs) were calculated using a fixed or random effects model.
Results: Dietaryfolate intake was not significantly associated with the risk of breast cancer. The combined RR with 95%CI forthe highest vs. lowest category dietary intake of folate [fifteen studies; 1,836,566 participants and 24,083 patientswith breast cancer] was 0.98 (0.90-1.05). Among subgroup analysis by menstrual status, hormonal status andthe consumption of alcohol, methionine and vitamin B12, no significant association was observed for the dietaryintake of folate and the risk of breast cancer. Dose-response analysis showed that a 220 μg/day increment indietary folate intake was not associated with the risk of breast cancer.
Conclusions: Our findings indicate thatdietary folate intake has no significant effect on the risk of breast cancer.