Dietary Intake of Folate, but not Vitamin B₂ or B₁₂, Is Associated with Increased Bone Mineral Density 5 Years after the Menopause: Results from a 10-Year Follow-Up Study in Early Postmenopausal Women

Folate, vitamin B₂ (riboflavin), and vitamin B₁₂ may affect bone directly or through an effect on plasma homocysteine levels. Previously, a positive association has been found between plasma levels and bone mineral density (BMD) as well as risk of fracture. However, there are limited data on whether dietary intakes affect bone. Our aim was to investigate whether intake of folate, vitamin B_2, and vitamin B₁₂, as assessed by food records affects BMD and fracture risk. In a population-based cohort including 1,869 perimenopausal women from the Danish Osteoporosis Prevention Study, associations between intakes and BMD were assessed at baseline and after 5 years of follow-up. Moreover, associations between intakes and 5- and 10-year changes in BMD as well as risk of fracture were studied. Intakes of folate, vitamin B₂, and vitamin B₁₂ were 417 (range 290–494) μg/day, 2.70 (range 1.70–3.16) mg/day, and 4.98 (range 3.83–6.62) μg/day, respectively, i.e., slightly above the intakes recommended by the United Nations Food and Agriculture Organization. At year 5, but not at baseline, cross-sectional analyses showed positive correlations between daily intake from diet and from diet plus supplements of folate and BMD at the femoral neck (P < 0.01). However, no associations were found between intakes and changes in BMD. During 10 years of follow-up, 360 subjects sustained a fracture. Compared with 1,440 controls, logistic regression analyses revealed no difference in intakes between cases and controls. A high dietary intake of folate, but not vitamin B₂ or B₁₂, exerts positive effects on BMD; but further studies are needed to confirm this association.