Which molecular weight of hyaluronic acid does Aroma-Zone favour in its formulations, and why?

Hyaluronic acid is a non-sulphated glycosaminoglycan, found in abundance naturally within tissues and particularly in the skin. The main property of hyaluronic acid is its remarkable ability to retain nearly 1,000 times its weight in water, which gives it exceptional moisturising properties. Hyaluronic acid reserves tend to decrease with age, hence the importance of incorporating it into skincare products. To ensure effective penetration into the various layers of the skin, the molecular weight of this molecule is a key factor. The lower its molecular weight, the better the hyaluronic acid will penetrate.

Where is hyaluronic acid naturally found in the skin?

Hyaluronic acid is found at the periphery and at the interfaces of the fibres of collagen and elastin fibres, where it helps to maintain these fibres in the correct configuration. In mature skin, the connections between the fibres and hyaluronic acid tend to become less frequent, which contributes to the disorganisation of collagen and elastin fibres, leading to the gradual formation of fine lines and wrinkles.

What is the link between hydration and the signs of ageing?

It has been recognised that restoring the skin’s optimal hydration helps to slow down the formation of fine lines, reduce the depth of wrinkles, promote cell regeneration and stimulate collagen production. This is precisely how hyaluronic acid works. The result is softer, smoother and more radiant skin (1).

Molecular weight (or the weight of a molecule) is measured in Daltons (Da). It has been shown that the penetration of hyaluronic acid in cosmetic products varies depending on its molecular weight (2). Low molecular weight (<20 kDa) hyaluronic acid penetrates the stratum corneum, whilst high molecular weight (50–3000 kDa) hyaluronic acid remains on the surface. However, just because hyaluronic acid molecules remain on the surface does not mean they are not beneficial. In fact, each molecular weight of hyaluronic acid plays a different role.</p><h4>Low-molecular-weight hyaluronic acid

It can penetrate the stratum corneum, the epidermis and the upper layers of the dermis.  

• It restores the skin barrier in its entirety

• It provides enhanced hydration within the skin

• It stimulates the natural production of collagen and hyaluronic acid

• It increases the skin’s elasticity and firmness

• It has a restorative effect and helps to reduce inflammation. 

The lower the molecular weight, the better the skin’s hydration and elasticity, and the greater the reduction in wrinkles.

Hyaluronic acid with an intermediate molecular weight

Intermediate molecular weights (around 50 kDa) act mainly in the superficial layers of the skin.

• They help to boost hydration in the epidermis

• They help to restore the skin barrier function

• They ensure continuity between the action of surface hyaluronic acids and those with a lower molecular weight.

They play an essential role in a combined formula, as they help ensure uniform hydration between the surface and the deeper layers of the skin.

High-molecular-weight hyaluronic acid

It has very limited permeability through the skin and remains mainly on the surface.  

• It forms a thin, protective layer of moisture on the skin’s surface

• It reduces water loss through evaporation (TEWL)

• It has a surface-lifting effect.

This synergy between the different molecular weights ensures continuous action from the surface right down to the deeper layers of the skin. The challenge, therefore, is not to choose between the different molecular weights, but to combine them intelligently within a single formulation.

Simply choosing a certain percentage of hyaluronic acid is not enough on its own to guarantee a product’s effectiveness. What matters is the balance between: the quality of the hyaluronic acid, the total concentration of hyaluronic acid, the distribution of different molecular weights, and their ability to act at different levels of the skin.

A study carried out on reconstructed epidermal models suggests, however, that certain concentrations, combined with a range of molecular weights, allow for better penetration into the stratum corneum whilst maintaining surface hydration (3). The study compared three serums containing 1 per cent, 2.5 per cent and 3.5 per cent hyaluronic acid. The result: the 3.5 per cent serum showed significantly greater penetration into the stratum corneum, whilst retaining the hyaluronic acid within the relevant layers of the skin. When combined with different molecular weights, this concentration therefore optimises the distribution of the active ingredient across the various layers of the skin, helping to retain it where it is most needed whilst minimising water loss.

At Aroma-Zone, we formulate our skincare products using a holistic approach to hyaluronic acid, combining different molecular weights and an appropriate concentration to optimise skin hydration. The formulas below illustrate this approach: combining several molecular weights to act at different levels.

3.5% Concentrated Hyaluronic Acid Serum

This 100% naturally sourced hyaluronic acid serum is one of the most concentrated on the market: 3.5 per cent compared to the 0.1 to 1 per cent hyaluronic acid found in conventional cosmetics. Renowned for smoothing, moisturising and plumping the skin, its fresh, naturally gel-like texture absorbs instantly without leaving a sticky residue or causing tightness. Its effectiveness as an anti-ageing serum has been tested and proven to fill in wrinkles, moisturise and improve the skin’s elasticity. It is composed of hyaluronic acid of various molecular weights (from 5 kDa to 1,800 kDa) to reach all layers of the skin. 

Discover our 3.5% Hyaluronic Acid Concentrated Serum

Hyaluronic Acid & Polyglutamic Acid Cream

This moisturising face cream combines next-generation hyaluronic acid and polyglutamic acid for 48 hours of hydration and supple, soft skin. It combines two types of hyaluronic acid with different molecular weights, covering a broad spectrum (<20 KDa to 3,000 KDa) for a comprehensive effect.

Discover our Hyaluronic Acid & Polyglutamic Acid Cream

100% hyaluronic acid serum pearls

These 100% pure hyaluronic acid pearls offer a new skincare routine, for revitalised and visibly rejuvenated skin in as little as 7 days. With just one application, they deliver an instant smoothing, revitalising and plumping effect, ideal for smoothing out fine lines before an event. Used as an intensive anti-ageing treatment, they provide long-lasting hydration whilst tackling the signs of ageing. True concentrates of hydration and radiance, these pearls encapsulate four different molecular weights of hyaluronic acid (from 10 kDa to 1,600 kDa), thanks to innovative freeze-drying technology. Directions for use: apply just one pearl to the face each day, either as a 7-day treatment or as and when required.

Discover our 100% Hyaluronic Acid Serum Pearls

Of course, using products consistently and incorporating various hyaluronic acid-rich products into your skincare routine enhances their effectiveness through synergistic action.

Emilie is a biochemistry and natural active ingredients engineer. Emilie is also a naturopath, nutrition adviser and writer specialising in health, nutrition and wellbeing. She has worked for over 10 years in the pharmaceutical industry and in scientific communication, which gives her a comprehensive understanding of health and enables her to discuss the subject with authority and clarity. Science is her foundation; words are her tools. She advocates a more preventative, more reasoned, more scientific and, of course, more natural approach to health!