First and foremost, hyaluronic acid is a polysaccharide that is not attached to a central protein and is distributed mainly in connective tissues and in particular in the extracellular matrix (present in the skin for 50% of the total stock of hyaluronic acid). Naturally present in the human body, this glycosaminoglycan is synthesised by three transmembrane enzymes, hyaluronan synthases (1, 2 and 3), present in epithelial and immune cells in particular.
Its molecular weight varies between 10 to the 5th Dalton to 10 to the 7th Dalton. Depending on the molecular weight of the hyaluronic acids, their actions change: high molecular weights have a more anti-inflammatory action, while low molecular weights increase angiogenesis (formation of blood vessels) and tissue repair, for example.
On a more practical level, the main roles of hyaluronic acid are for:
The skin: skin hydration (powerful hydrophilic), tissue cohesion (therefore role in skin texture, elasticity and firmness), restoration of the skin barrier (cell regeneration and skin healing), regulation of angiogenesis, anti-inflammatory role (reduction in redness and skin discomfort). All in all, fine lines are reduced and the skin is plumper and more hydrated.
Joints: increase in the viscosity of synovial fluid (thus reducing joint friction and relieving any pain), maintenance of cartilage elasticity.
Hair: the intense hydration it provides makes it an indispensable ally for the hair. It can retain up to 1,000 times its weight in water, making it an excellent ingredient for deeply moisturising dry, damaged hair. It helps to soften hair and make it easier to style, reducing frizz and split ends.
This molecule is extremely well tolerated, with no risk of side effects. It is therefore also suitable for highly sensitive or intolerant skin.
Finally, hyaluronic acid is broken down by an enzyme, hyaluronidase, which is naturally present in our bodies. Its breakdown is all the more stimulated in the event of significant oxidative stress, inflammation, smoking or exposure to UV sunlight.