Hydroxyapatite is an association of natural minerals and a composition of trace elements present in the human body. They are nutritious elements present in the body and food as organic and non-organic compositions. Many body tissues are made of these elements, they are found for instance in bone and in teeth and they are essential for physical and mental well-being, in that they constitute the whole tissue structure and fluids of the human body.

Important as they are in the maintenance of all physiological processes, they strengthen the bone structures by catalyzing several biochemical reactions; they play an important role in the production of hormones and antibodies, thus keeping the delicate hydric structure in balance. All the minerals considered necessary for the body must be present in the diet as essential food substances that the body is either unable to synthesize at all or in insufficient quantities.

Such elements are irreplaceable: they in fact set in motion processes and reactions in the body which allow for life and well-being. They usually act as a catalyst: they start and allow enzymatic functions - which are the basis of cellular functions - to be fulfilled. It is a naturally occurring form with the formula (Zn, Mn, Mg) (Ca)5 (PO4)3(OH) (Lactate), to denote that the crystal unit cell comprises more entities.

Hydroxyapatite crystallizes in the hexagonal crystal system. It has a specific gravity of 3.08 and is 5 on the Mohs hardness scale. Pure Hydroxyapatite powder is white and, in skincare preparations, a viscous powder suspension with 28-30% suspended solids as a complex of nanoparticles.

Evaluations show that, when introduced into several types of sunscreen formulas, Hydroxyapatite gave better performances than titanium dioxide (TiO2), in values variable from 2 to 18% higher than standard sunscreen grade TiO2. In other words, Hydroxyapatite showed seemingly better or at least comparable sunscreen efficiency as micronized titanium dioxide, with the interesting advantage of complete physiological compatibility.

Moreover, its ions are slowly incorporated into the skin structure, so that no solid residues are left on the surface in the long-term. In the field of anti-age efficacy, the ingredient proved to perform a statistically significant soft-focus effect (by sensory evaluation) a statistical decrease of deep wrinkles, and a tendential decrease of average rugosity (by skin replica).

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