Introduction: Folate deficiencies may be linked to depressive disorders among persons suffering from neurological and psychiatric problems. The purpose of the present study was to evaluate the impact of dietary folate intake on depressive symptoms in young Japanese women of reproductive age.
Methods: The study was conducted in Japan in 2009 with 141 Japanese women aged 18 to 28 years. A Japanese version of the Center for Epidemiologic Studies Depression (CES-D) scale was used to screen for depressive symptoms. Dietary intake was investigated by a diet history questionnaire. Nonfasting blood samples were collected from the women to measure folate and homocysteine levels.
Results: The proportion of women with lower folate intake (< 240 μg/d) was significantly higher in the women with CES-D scores greater than or equal to 19 when compared with the folate levels in those with CES-D scores less than 19 (75.0% vs 43.6%, respectively; P < .001). Logistic regression analysis revealed significant associations between CES-D scores greater than or equal to 19, low folate intake, and low vitamin B6 intake when adjusted for age, living status, smoking, and body mass index. Adequate folate intake of more than the recommended dietary allowance (RDA) level of 240 μg per day was independently related to a decreased risk of depression (adjusted odds ratio 0.22; 95% confidence interval, 0.11-0.56; P < .001).
Discussion: Multiple logistic regression analysis revealed a reduced incidence of depression in women whose intake of folate exceeded the RDA of 240 μg per day. This finding suggests that dietary folate intake may be causally related to depressive symptoms in women of reproductive age. If results of studies powered to determine causal relationships are similarly positive, folate supplementation could reduce the incidence of depression.