You find it in serums, creams, masks and even some mists. Hyaluronic acid has become one of the best-known ingredients in cosmetics.
But what does it really do?
Its main benefit for the skin comes from its ability to retain water. Naturally present in our body, including in the skin, hyaluronic acid contributes to its hydration and its mechanical properties.
An ingredient that loves water
Hyaluronic acid belongs to a family of molecules able to bind large amounts of water.
In a cosmetic product, it acts mainly as a humectant: it helps keep water in the upper layers of the skin and can thereby improve its hydration level.
This is what explains the feeling of softer, more comfortable skin you may notice after applying a product that contains it.
But hyaluronic acid does not literally "fill" the skin with water. Nor is it a permanent supply of water: its effect depends on the complete formulation of the product and on the skin environment.
Why do we talk about several hyaluronic acids?
This is one of the most interesting aspects of the ingredient.
Hyaluronic acid can be used in different forms and with different molecular weights.
To simplify, high molecular weight molecules stay more on the surface of the skin and can help form a hydrating film. Lower molecular weight forms have different properties and can interact with deeper layers of the epidermis.
This means there is no single "hyaluronic acid" that always works the same way.
The size of the molecules is part of the formulation.
Clinical studies have also observed different effects depending on the molecular weights used, notably on skin hydration.
Hydrating does not mean nourishing
The two notions are often mixed up.
Dehydrated skin mainly lacks water. It can look dull, show small dehydration lines or feel tight.
Dry skin, on the other hand, lacks lipids. It needs to be nourished and to reinforce its barrier function.
The same skin can in fact be both dry and dehydrated.
Hyaluronic acid mainly addresses the issue of hydration. It does not replace lipid or nourishing ingredients when skin needs them.
Is it an anti-ageing ingredient?
This is where we need to distinguish between the hydrating effect and marketing promises.
Properly hydrated skin generally looks suppler, and small lines linked to dehydration can be less visible.
Studies on formulations containing hyaluronic acid have also shown improvements in hydration and in some parameters linked to elasticity and the appearance of wrinkles.
But that does not mean a hyaluronic acid serum "erases" wrinkles.
Its value is above all that of a well-documented hydrating active, which can contribute to the comfort and appearance of the skin.
How to fit it into a routine?
Hyaluronic acid can be used morning and evening, depending on the product's formula.
It naturally fits after cleansing and before a cream or another care product, if your routine includes one.
The key is to look at the whole formula, rather than choosing a product only because it says "hyaluronic acid" on the label.
At Kinselo, hyaluronic acid is part of Sève Légère, a serum designed around light, comfortable hydration.