Cal-Assimilate Plus®Item Description Cal Assimilate Plus contains calcium in three forms: microcrystalline hydroxyapatite, a natural whole bone mineral; calcium citrate, a bioavailable, readily soluble form of calcium; and tricalcium phosphate, a major constituent of the bone matrix. Two forms of magnesium, plus other key minerals and vitamin D, are included to assist in optimal calcium absorption and metabolism.* Chondroitin sulfate is included to support the bone