The systematic review and meta-analysis of trials by Cockayne et al1 indicates the preventive effect of vitamin K supplementation on fractures in a high-risk population. The authors analyzed the data presented in 7 trials performed in Japan, which uniformly indicated that the large daily dose of vitamin K (45 mg/d), given as menaquinone-4, for 12 to 24 months was beneficial. The synthetic vitamin used in these trials was manufactured by Eisai Co, Ltd (Tokyo, Japan).
Tamura T, Morgan SL, Takimoto H. Vitamin K and the Prevention of Fractures. Arch Intern Med. 2007;167(1):94. doi:10.1001/archinte.167.1.94-a