Vitamin D Supreme provides a clinically useful dose of vitamin D3 along with vitamin K as both K1 and K2. This formula contains higher targeted doses than Vitamin D Synergy for situations where more aggressive repletion is required. Vitamins D and K are essential for optimal bone and arterial health and for maintaining the immune system in proper balance. The amount of vitamin D and K in this formula may be beneficial for those who do not get adequate sun exposure and/or dietary sources of these vitamins. Vitamins D and K work as a team. Thus, increasing doses of vitamin D will increase the need for vitamin K..