Vitamin D is important for calcium absorption, bone health, and immune function, but it does not directly influence blood clotting. It works closely with calcium and phosphorus to build strong bones and regulate muscle function. While some research has explored potential links between vitamin D and cardiovascular health, it is not responsible for the clotting process. That’s vitamin K’s job. Confusing the two may stem from their shared role in bone health — as vitamin D helps absorb calcium, and vitamin K helps bind it to bone — but they serve distinct functions. If you’re focused on healthy clotting, vitamin K is the key nutrient to know.