Both Vit D and K2 are fat-soluble vitamins. Both play a central role in calcium metabolism. Vitamin D3 ensures that calcium is absorbed easily from the food while K2 (MK-7) activates the protein osteocalcin, which integrates calcium into bone and prevents calcium from being deposited elsewhere. Many animal and human studies suggest Vit D3 has a positive effect on the metabolism of Vit K2 and also promotes K-dependant bone proteins (23), (24). They work synergistically for bone and cardiovascular health. Yet, there are a few studies that have not observed any such synergistic effect of combining Vit D and K2 together (25). Aggregating all the evidence regarding a combined vitamin D and K supplementation, the majority of the studies found beneficial effects.