Limited evidenceVitamins & minerals

Microcrystalline Hydroxyapatite (MCHA)

Ground bone-matrix calcium that also contains collagen and trace minerals. Older reviews are enthusiastic, but the best controlled comparison found it equivalent to — not better than — ordinary calcium salts.

Evidence last reviewed: August 2026

What the science says

Equivalent, not superior, to plain calcium salts Moderate evidence
A randomized trial in 100 postmenopausal women compared two MCHA preparations with calcium citrate/carbonate and placebo. MCHA raised ionised calcium less (but raised phosphate more) and produced comparable reductions in bone turnover markers at 3 months — equivalence, not an advantage.
Favourable reviews rest on weak studies Limited evidence
A narrative review of the ossein-hydroxyapatite complex concluded it preserves bone mass better than calcium carbonate, but it draws on older, small and largely industry-linked trials using bone-density surrogates rather than fractures.
No fracture data Strong evidence
No trial has tested MCHA against fractures. The wider evidence base — a 2026 review of 69 trials in 153,902 people — shows calcium supplementation in general has little to no effect on fracture or fall risk.

Dosage & safety

Studied doseProducts supply roughly 500–1000 mg elemental calcium per day from MCHA, best split across meals. Trials used 1 g/day of elemental calcium.

SafetyConstipation and bloating like other calcium supplements. Because it is made from animal bone, heavy metals are a genuine quality concern: lead and aluminium have historically been found in bone-derived and "natural source" calcium products, so choose brands that publish contaminant testing. It also supplies phosphate, which is a consideration in kidney disease. Same interactions as any calcium: levothyroxine, iron, and some antibiotics.

Scientific references

Acute and 3-month effects of microcrystalline hydroxyapatite, calcium citrate and calcium carbonate on serum calcium and markers of bone turnover: a randomised controlled trial in postmenopausal women
Bristow SM, Gamble GD, Stewart A — Br J Nutr, 2014
Use of ossein-hydroxyapatite complex in the prevention of bone loss: a review
Castelo-Branco C, Dávila Guardia J — Climacteric, 2015
Calcium, vitamin D, or combined supplementation to prevent fractures and falls: systematic review and meta-analysis
Massé O, Mercurio CM, Dupuis S — BMJ, 2026

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