This D3 Vitamin 5000 Iu supplement supports bone, teeth, muscle, and immune health. It's crafted with cholecalciferol, an easily absorbed and utilized form of Vitamin D3.+ The Vitamin K2 in this supplement supports the function of D3, working together to support strong, healthy bones. In fact, Vitamins D3 and K2 work better for bone health than Vitamin D3 alone.