Serum levels of vitamin B12 are not related to low bone mineral density in postmenopausal Brazilian women

Introduction: Osteoporosis and vitamin B12 deficiency are conditions with an increasing prevalence over time. It has been described an association between low serum vitamin B12, osteoporosis and increased risk of bone fractures, but the studies are heterogeneous and the results are controversial. Objective: To investigate the association between plasma levels of vitamin B12 and bone mineral density in a group of asymptomatic women after menopause. Methods: Asymptomatic postmenopausal women were consecutively invited to participate in this cross-sectional study. Bone mineral density (lumbar spine and femur) was measured by DXA Lunar Prodigy Vision, and blood levels of vitamin B12, calcium, phosphorus, bone alkaline phosphatase (BAF), and parathyroid hormone were determined. For the diagnostic of osteoporosis the World Health Organization criteria were considered. Results: Seventy women were included, mean age 62.5 +/- 7 years. Eighteen (25.7%) women had normal bone mineral density, 33 (47.1%) had osteopenia and 19 (27.1%) had osteoporosis. Six (8.6%) patients had wrist fracture; two (2.8%) reported a diagnosis of vertebral fracture and only one (1.4%) patient had suffered a hip fracture. The levels of vitamin B12 (mean +/- SD, pg/mL) of women with normal bone mineral density, osteopenia and osteoporosis were 590.2 +/- 364.3, 536.6 +/- 452.3, and 590.2 +/- 497.9, respectively (P = 0.881). Multiple regression analysis showed that body mass index and BAF were the main predictors of lumbar spine bone mineral density. Conclusion: The results indicate that vitamin B12 serum levels are not related to bone mineral density in this group of Brazilian postmenopausal women.