Low-dose vitamin K2 (MK-4) supplementation for 12 months improves bone metabolism and prevents forearm bone loss in postmenopausal Japanese women 

This 2014 randomized, double-blind, placebo-controlled, parallel-group trial performed as an intervention study examined the effects of 1.5 mg MK-4 daily for 12 months on bone mineral density (BMD), using biomarkers of bone turnover in postmenopausal Japanese women. Fifty postmenopausal women 50–65 years were recruited and assigned 1.5 mg (1,500 mcg, as six tablets) of MK-4 daily or placebo. Researchers concluded that the 6-12 month low-dose MK-4 supplementation in postmenopausal women improved bone quality without substantial adverse effects by decreasing the serum concentrations of ucOC. 

References:

Koitaya N, Sekiguchi M, Tousen Y, Nishide Y, Morita A, Yamauchi J, Gando Y, Miyachi M, Aoki M, Komatsu M, Watanabe F, Morishita K, Ishimi Y. Low-dose vitamin K2 (MK-4) supplementation for 12 months improves bone metabolism and prevents forearm bone loss in postmenopausal Japanese women. J Bone Miner Metab. 2014 Mar;32(2):142-50. doi: 10.1007/s00774-013-0472-7. Epub 2013 May 24. PMID: 23702931