The different forms of Hyaluronic Acid available

Hyaluronic Acid, a molecule naturally present in the dermis but which degrades over time.

Hyaluronic acid is a hydrophilic molecule naturally present in the human body in the joints, muscles, eyes, and especially the skin. It constitutes the extracellular matrix and supports collagen and elastin fibers. Hyaluronic acid captures and retains water molecules, thus providing hydration and lubrication.

With age, hyaluronic acid production decreases, and reserves drop. At the skin structure level, there is sagging, loss of elasticity and firmness, the appearance of increasingly deep wrinkles, and dryness.

It is therefore understood that it is beneficial to provide the skin with hyaluronic acid through topical skincare, i.e., using creams or serums.

Hyaluronic Acid, a promising molecule, but in what form?

1- Uncrosslinked Hyaluronic Acid

In topical cosmetics, meaning those applied directly to the skin, Hyaluronic Acid is always in its UNCROSSLINKED form. There are different forms of uncrosslinked Hyaluronic Acid.

"Sodium Hyaluronate," "Hyaluronic acid," "Hydrolysed hyaluronic acid," "Sodium Hyaluronate Crosspolymer," "Sodium Acetylated Hyaluronate" are all active ingredient names that refer to the same molecule: Hyaluronic Acid. So, how do you make sense of it?

High Molecular Weight Hyaluronic Acid: the RAW form

"Hyaluronic acid"

Hyaluronic acid in its basic form is a large, long-chain molecule. We refer to it as high molecular weight (>1,800kDa).

In this form, the Hyaluronic Acid molecule will remain on the skin's surface. It cannot penetrate the dermis because it cannot cross the skin barrier.

By remaining on the surface, Hyaluronic Acid plays a significant role: it creates a protective film on the skin, thus protecting it from external aggressions by reinforcing the hydrolipid film. The superficial layer of the skin is hydrated and tightened. This is the hyaluronic acid of choice for hydrating fine, unsightly dehydration lines.

Medium Molecular Weight Hyaluronic Acid: the hydrolyzed form

"Hydrolysed hyaluronic acid"

Hyaluronic acid in its medium form is a molecule that has been fractionated into medium-sized pieces by a chemical process.

We refer to it as medium molecular weight hyaluronic acid (> 1,000-1,800kDa).

It is stored in the skin's connective tissue and prevents water from evaporating. It will therefore help regulate dehydration.

Low Molecular Weight Hyaluronic Acid: the alkaline form

"Sodium Hyaluronate"

Sodium Hyaluronate is a name often found in cosmetic formulations because it is a very stable form. It refers to the smallest form of Hyaluronic Acid. We refer to it as low molecular weight hyaluronic acid (> 50-1000kDa).

Sodium Hyaluronate corresponds to the alkaline form, i.e., hyaluronic acid salts.

Thanks to its very small weight, Hyaluronic Acid will penetrate deeper into the epidermis. Thus, it will boost the production of hyaluronic acid already present in the skin. It will provide more intense nourishment and prevent skin sagging.

The acetylated form of Hyaluronic Acid

"Sodium Acetylated Hyaluronate"

A lesser-known but promising form in cosmetics.

This form of hyaluronic acid has both lipophilic and hydrophilic properties. Scientific research has shown that this form can absorb three times more water than ordinary hyaluronic acid and ensures prolonged hydration.

2-Crosslinked Hyaluronic Acid

In its crosslinked form (Sodium Hyaluronate Crosspolymer), Hyaluronic Acid takes on a whole new dimension. It will be used to fill spaces or create volume.

Crosslinked hyaluronic acid is obtained by a chemical process from a hyaluronic acid salt combined with a crosslinking agent. The hyaluronic acid molecule will then be "giant" but stable thanks to the "salt" form of hyaluronic acid. It will therefore have a very high humectant capacity (retaining water).

This form of Hyaluronic Acid is the one found in injectable hyaluronic acid for aesthetic medicine treatments.

If crosslinked hyaluronic acid is spread on the skin, it will have absolutely no effect. It cannot be retained on the skin's surface. It is intended to be injected deep to exert its action.