Efficacy and safety of vitamin K2 for postmenopausal women with osteoporosis at a long-term follow-up: meta-analysis and systematic review

Introduction Vitamin K2 supplementation has been revealed to be effective in the prevention and treatment of osteoporosis in Japan, but further proof for the effectiveness of this practice is still needed. Objective To investigate whether vitamin K2 supplementation plays a role in maintaining bone mineral density (BMD) and reducing the incidence of fractures for postmenopausal women with osteoporosis at a long-term follow-up. Materials and methods We searched systematically throughout the databases of PubMed, Cochrane library, and EMBASE from the dates of their inception to November 16 2021 in this meta-analysis and systematic review, using keywords vitamin K2 and osteoporosis. Results Nine RCTs with 6853 participants met the inclusion criteria. Vitamin K2 was associated with a significantly increased percentage change of lumbar BMD and forearm BMD (WMD 2.17, 95% CI [1.59–2.76] and WMD 1.57, 95% CI [1.15–1.99]). There were significant differences in undercarboxylated osteocalcin (uc-OC) reduction (WMD −0.96, 95% CI [−0.70 to 0.21]) and osteocalcin (OC) increment (WMD 26.52, 95% CI [17.06–35.98]). Adverse reaction analysis showed that there seemed to be higher adverse reaction rates in the vitamin K2 group (RR = 1.33, 95% CI [1.11–1.59]), but no serious adverse events related to vitamin K2 supplementation. Conclusion This meta-analysis and systematic review seemed to support the hypothesis that vitamin K2 plays an important role in the maintenance and improvement of BMD, and it decreases uc-OC and increases OC significantly at a long-term follow-up. Vitamin K2 supplementation is beneficial and safe in the treatment of osteoporosis for postmenopausal women.