Vitamin K2 (menaquinone-7) Prevents Age-related Deterioration of Trabecular Bone Microarchitecture at the Tibia in Postmenopausal Women

Objective: Clinical studies suggest that vitamin K2 protects against bone loss and fractures; however, its effect on bone quality has never been investigated. We investigated the effect of vitamin MK-7 on undercarboxylated osteocalcin (ucOC), and bone mass and quality.

Design: We conducted a randomised, placebo-controlled, double-blinded clinical trial.

Methods: We investigated the effect of MK-7 375 µg for 12 months on bone mineral density (BMD) measured by dual X-ray absorptiometry (DXA), bone microarchitecture measured by high-resolution peripheral quantitative computed tomography (HRpQCT) and biochemical bone turnover markers in 148 postmenopausal women with osteopenia. All of them were supplemented with calcium and vitamin D.

Results: ucOC decreased in the MK-7 group (-65.6 (59.1; 71.0) %) (median (CI)) compared with the placebo group (-6.4 (-13.5; 1.2) %) after 3 months (P < 0.01). HRpQCT after 12 months demonstrated that trabecular number in tibia was unchanged in the MK-7-group (-0.1 ± 1.9%) (mean ± s.d.) and decreased in the placebo group (-3.5 ± 2.2%), trabecular spacing was unchanged in the MK-7 group (+1.2 ± 8.0%) and increased in the placebo group (+4.5 ± 9.7%), and trabecular thickness was unchanged in the MK-7 group (+0.2 ± 1.7%) and increased in the placebo group (+4.0 ± 2.2%) (between-group changes for all: P < 0.05). There were no significant differences between the groups in HRpQCT-derived parameters at the radius or in BMD at any site.

Conclusion: The changes in bone microarchitecture in the placebo group are consistent with the age-related deterioration of trabecular structure, with a loss of trabeculae and a greater mean thickness of the remaining trabeculae. This suggests that vitamin MK-7 preserves trabecular bone structure at the tibia.