Natural Factors Calcium & Magnesium Citrate with D3 - Essential for the development and maintenance of healthy bones and teeth, everyone should be sure to maintain adequate levels of Calcium - especially women who are prone to osteoporosis. Calcium is also vital for proper muscle development and functionality, can help blood clotting, may assist in lowering blood pressure and helps activate many enzymes. When mixed with Magnesium and other supporting minerals, Calcium's ability to do its job is greatly enhanced. Natural Factors Calcium Magnesium Citrate is a 1:1 combination of Calcium and Magnesium with Vitamin D3, plus Potassium, Zinc and Manganese in citrate form making it easy to absorb, highly bio-available, and easy to assimilate.