Associations between dietary intake of B-vitamins and psychological disorders among Iranian women: a cross-sectional study.

OBJECTIVE: B-vitamins affect brain function through multiple pathways. Given limited evidence on the relationship between dietary intake of these vitamins and psychological disorders, we examined dietary intake of vitamin B6-9-12 in relation to psychological disorders among Iranian women. DESIGN: Cross-sectional study. Dietary intake was assessed using a valid and reliable FFQ. To assess psychological disorders, we used a version of the Depression Anxiety Stress Scale-21 validated in Iran. SETTING: Ten public health centres in southern Tehran, Iran. PARTICIPANTS: A total of 447 female participants aged 20-50 years. RESULTS: The median values of vitamin B6 (pyridoxine), B9 (folate) and B12 (cobalamin) were 1·30 mg/d, 313·89 µg/d and 3·99 µg/d, respectively. After adjustment for potential confounders, dietary vitamin B6 intake was associated with lower odds of depression (OR: 0·54; 95 % CI: 0·31, 0·95; Ptrend: 0·03). However, there was a positive association between dietary vitamin B12 intake with the odds of depression (OR: 2·05; 95 % CI: 1·17, 3·60; Ptrend: 0·01) and psychological distress (OR: 2·00; 95 % CI: 1·17, 3·41; Ptrend: 0·01). No association was found between vitamin B9 with any psychological disorders. CONCLUSIONS: Women with higher dietary intakes of vitamin B6 had lower likelihood of depression. However, women with higher dietary intake of vitamin B12 had higher odds of depression and psychological distress. Future prospective studies in different populations are needed to clarify whether B-vitamin deficiency is a cause or consequence of psychological disorders.