Both vitamin D and vitamin K2 support bone and muscle health, along with cardiovascular health and immune function. It is important to maintain an optimal level of vitamin D in the body through all stages of life, from foetal development to old age. Vitamin K2, a series of molecules known as menaquinones, exerts a more powerful influence on bone than does vitamin K1. The vitamin K2 in this formula is the well-studied MK-4. Combining vitamins D and K can provide greater support of the immune and cardiovascular systems than each offers separately. For example, vitamin D is necessary for calcium absorption, and vitamin K is important for directing calcium to the bones and away from the soft tissues, such as blood vessels and kidneys.