A clinical trial conducted in China looked at the effects of Vitamin K2 on bone density in adults aged 50 to 75. Subjects received 90 mcg of K2 or a placebo every day for 1 year. At the end of the trial, it was found that women receiving K2 had improved bone density status as measured at the top of the thigh bone as compared to the woman receiving a placebo.
Zheng et al. (2020). Effect of Low-Dose Vitamin K2 Supplementation on Bone Mineral Density in Middle-Aged and Elderly Chinese: A Randomized Controlled Study. Calcif Tissue Int. 106(5):476-485.