Bone, ash (68439-86-1)

Hydroxylapatite (CAS No.:68439-86-1) is a naturally occurring mineral form of calcium apatite with the formula Ca₅(PO₄)₃(OH), but is usually written Ca₁₀(PO₄)₆(OH)₂ to denote that the crystal unit cell comprises two entities.It is the hydroxyl endmember of the complex apatite group. The OH- ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. It has a specific gravity of 3.08 and is 5 on the Mohs hardness scale. Pure hydroxylapatite powder is white. Naturally occurring apatites can however also have brown, yellow or green colorations, comparable to the discolorations of dental fluorosis.Up to fifty percent of bone is made up of a modified form of the inorganic mineral hydroxylapatite.Carbonated-calcium deficient hydroxylapatite is the main mineral of which dental enamel and dentin are comprised. Hydroxyapatite crystals are also found in the small calcifications (within the pineal gland and other structures) known as corpora arenacea or 'brain sand'.It is marketed as a "bone-building" supplement with superior absorption than calcium.It is a second-generation calcium supplement derived from bovine bone.In the 1980s, bone meal calcium supplements were found to be contaminated with heavy metals,and although the manufacturers' claim their MH is free from contaminants, people are advised to avoid it because it has not been well-tested.However, the limited tests seem to show positive results. A 1995 randomized placebo-controlled study of 40 people in Europe found that it was more effective than calcium carbonate in slowing bone loss.A 2007 randomized double-blind controlled study of an MH supplement called the Bone Builder found significant positive effects in bone mineral density (BMD).