Bone Builder^® with Magnesium provides bone health support with microcrystalline hydroxyapatite concentrate (MCHC), a highly absorbable crystalline compound comprised of naturally-occurring organic components of bone which is backed by over 30 years of research. MCHC contains naturally occurring calcium, phosphorus, and trace amounts of other minerals, bone growth factors, collagen and other vital bone proteins. This well-rounded formula is designed to support bone mineral density and also features vitamin D and magnesium for enhanced bone support and healthy muscle function.