Loss of bone mass and the frequently associated osteoporosis primarily affect middle-aged and older individuals. One of the main risk groups consists of women who have undergone menopause. A decrease in bone mineral density (BMD) results in increased bone fragility and, consequently, a higher risk of fractures and a reduced quality of life. As a preventive measure against osteoporosis, calcium and vitamin D supplementation are commonly recommended. In recent years, studies have also investigated the role of vitamin K2 in bone metabolism.
Vitamin K2 is essential for the γ-carboxylation of osteocalcin, a protein responsible for proper binding of calcium to the bone matrix. Consequently, reduced activity of this vitamin leads to higher levels of undercarboxylated osteocalcin, which in turn results in insufficient bone mineralization. In the publication discussed below, the authors examined the effect of vitamin K2 supplementation on bone mineral density and biochemical markers of bone metabolism in middle-aged and elderly patients. The study was randomized and double-blind, conducted over a 12-month period. This design allowed for the observation of both short- and long-term changes in bone structure in the participants.
The study group consisted of 311 individuals, including men and postmenopausal women aged 50 to 75 years. Each participant was randomly assigned to one of four groups. The first group received a placebo; the second group received vitamin K2 at a dose of 50 μg per day; the third group received vitamin K2 at a dose of 90 μg per day; and the fourth group received vitamin K2 at a dose of 90 μg per day in combination with calcium at a dose of 500 mg per day and vitamin D3 at a dose of 10 μg per day.
Bone mineral density was measured in the lumbar spine, total hip, and femoral neck. These sites are clinically relevant because of the significant bone mass loss observed in these regions in patients with osteoporosis. Measurements were performed using densitometric techniques before the start of the study and repeated after 12 months. In addition, several biochemical markers of bone metabolism were assessed, including carboxylated osteocalcin (cOC), undercarboxylated osteocalcin (ucOC), and the cOC/ucOC ratio.
The obtained results indicate a significant slowing of bone mass loss in women from groups 3 and 4. Statistical analysis demonstrated a significant interaction between treatment and study duration. Furthermore, in women receiving vitamin K2 at a dose of 50 μg/day, no statistically significant slowing of bone mass loss was observed. Among male participants, no statistically significant effect of vitamin K2 supplementation was observed across groups. This suggests a sex-dependent physiological response to vitamin K2 supplementation.
In women in groups 2, 3, and 4, significant improvements in biochemical markers of bone metabolism were observed, most notably an increase in the cOC-to-ucOC ratio. This finding suggests a substantial effect of vitamin K2 on osteocalcin carboxylation. The improvement was greater in women from groups 3 and 4 than in those from group 2, indicating a dose-dependent effect. Importantly, no significant difference was observed between the results of women from groups 3 and 4, suggesting little or no additional effect of calcium and vitamin D3 on osteocalcin carboxylation.
The study also demonstrated that vitamin K2 supplementation is safe and well-tolerated in patients. No serious adverse events were reported, and participants adhered to the supplementation protocol throughout the entire study period.
In summary, the study demonstrates that vitamin K2 supplementation at 90 μg/day may effectively slow bone mass loss in postmenopausal women and significantly improve markers of bone metabolism. These results indicate that vitamin K2 is an important factor in maintaining bone health in postmenopausal women. The authors also emphasize the need for further long-term studies to determine the impact of supplementation on fracture risk reduction and sustained long-term benefits.
Prepared based on:
Zhang, Yingfeng, et al. “Effect of low-dose vitamin K2 supplementation on bone mineral density in middle-aged and elderly Chinese: a randomized controlled study.” Calcified Tissue International 106.5 (2020): 476–485.
