NOW combines two nutrients extensively researched for their contribution to the health of bones, teeth and the cardiovascular system. Vitamin D3 promotes Calcium transport and absorption. Recent studies indicate that Vitamin D3 may play a role in the immune system. Vitamin K is critical for the formation of a healthy, strong bone matrix. Vitamin K's role in arterial health revolves around its ability to support proper Calcium metabolism in vascular structures. Vitamin K2 is a readily active and biologically available form of Vitamin K.