Hyaluronic acid in cosmetic formulas

Belinda Carli, 08/02/2022

Hyaluronic acid is a key molecule involved in skin hydration, however there is a lot of misinformation about the use of hyaluronic acid in skincare formulas. There are significant benefits from using sodium hyaluronate and hydrolysed hyaluronic acid in skincare, but it is likely to be quite different to what you thought.

 

In this blog we will look at the science of hyaluronic acid in the skin, as well as what happens when it is topically applied. We will also consider the various molecular weights of sodium hyaluronate available and how each can benefit your skin care formulations.

HOW PEPTIDES WORK IN COSMECEUTICALS

HA FACT 1: The hyaluronic acid in your skin is not the same as the sodium hyaluronate in a formula

This is probably the least understood differences between the substance that occurs in the skin, and the substance that gets used in formulas.

We have hyaluronic acid in the skin – a glycosaminoglycan substance found extensively in the extra cellular matrix, that binds water strongly, keeping our skin supple and hydrated.

 

Hyaluronic acid polymer

 

We use sodium hyaluronate in cosmetic formulas. It is the sodium salt of hyaluronic acid, and has better oxidative stability and a lower molecular weight than hyaluronic acid, making it much better to use in formulas, for enhanced penetration, and better shelf life.

 

Sodium hyaluronate polymer

 

Almost all so called ‘hyaluronic acid’ in formulas is sodium hyaluronate. Very low molecular weight forms may be hydrolysed hyaluronic acid. If you check the ingredient list of your product, you will usually see these terms used as the correct nomenclature of the ingredients.

 

HA FACT 2: Topically applied hyaluronic acid and sodium hyaluronate do NOT penetrate to the dermis

This is another big internet furphy we need to clarify. There is a lot of talk about ‘size’ and ‘molecular weight’, and while these are important (and we’ll delve into this in a moment), any sodium hyaluronate or hyaluronic acid that is applied topically does NOT penetrate through to the dermis.

Their pathway from topical application to deeper entry is blocked at the lipid-rich stratum granulosum1. Interestingly, the hyaluronic acid synthesized within the skin is similarly trapped inside by the same lipid barrier. This is a good thing though – it helps keep the hyaluronic acid within your skin and with it, vital hydration.

 

So, there is hyaluronic acid synthesized by the body in the dermis, and that is held below the level of the stratum granulosum to keep moisture in the skin. There is also hyaluronic acid above the stratum granulosum – this is more easily lost, but also replaced, with cosmetic products.

 

HA FACT 3: Hyaluronic acid in the skin depletes as we age

This is a fact that is widely known. When we are young, there is plenty of hyaluronic acid present at both levels of the skin to bind water and keep our skin looking plump and feeling soft. As we age, the level of hyaluronic acid in both locations diminishes, and this contributes to drier, rougher skin as well as less supple, thinner looking skin.

 

 

There are several things we know about hyaluronic acid as the skin ages1:

  • Epidermal hyaluronic acid is synthesised at a different rate to dermal hyaluronic acid
  • Hyaluronic acid at both levels reduces in size over time, reducing its ability to bind as much moisture
  • Hyaluronic acid in the dermis binds with tissue structures to reduce its water binding capacity

All of these factors contribute to the appearance of ageing: dryness, roughness, lack of suppleness/plumpness and development of fine lines and wrinkles (along with collagen losses).

 

HA FACT 4: Size does not matter as much as you think 

This is another area we need to clarify. While the size/molecular weight of the sodium hyaluronate does matter to obtain specific benefits, all sodium hyaluronate will benefit the skin.

The question is: what do you want it to do?

The very low molecular weight sodium hyaluronate will have the deeper absorption (to the stratum granulosum, potentially), this will not yield perceivable benefits for younger skin types, where its long lasting moisture benefits wouldn’t be as necessary. All skin types can benefit from high molecular weight sodium hyaluronate, because it creates a moisture protective film at the surface of the skin, and this benefits everyone.

You can even use a combination of both – for very dry, aged skin, you could use very low molecular weight hydrolysed hyaluronic acid for its moisture boosting and anti-wrinkle effects, and combine this with high molecular weight sodium hyaluronate for moisture protection at the surface of the skin.

Here is a summary of how to make selections based on formulation requirements and their molecular weight:

Type

MW range

Function

High MW sodium hyaluronate

>1600kDa

Moisture protective film, long lasting moisturization, trans-epidermal water loss protection, good suppleness retention

Medium MW sodium hyaluronate

200kDa – 1600kDa

Good moisturising and suppleness effect, slower release/absorption

Low MW sodium hyaluronate

10kDa – 200kDa

Good absorption and benefits within the epidermis, long lasting moisturising effect

Oligo sodium hyaluronate

<10kDa

Ready epidermal absorption, deeply moisturising, anti-ageing benefits and recovery after sunburn

 

HA FACT 5: You don’t need much in a formula for great skin benefits

Search for how much to use, and you’ll be lost once again! So let’s set the record straight.

Sodium hyaluronate comes in one of two forms:

  • Powder – 100% strength
  • Liquid – typically a 1% solution

Typical input rates for the benefits listed above would be:

  • 0.1 – 0.5% w/w as a powder
  • 10 – 50% w/w as a solution

You can also use 2%w/w of high molecular weight sodium hyaluronate to create viscous, hydrating gels.

When adding to your formula, just remember:

  • Do not heat – otherwise it will oxidise and degrade rapidly
  • Do not expose to high shear – otherwise you will cut its strands, and it will lose its moisture binding capacity

 

 

Learn how to formulate with sodium hyaluronate effectively…

 

Happy formulating!

 

Reference:

1. Papakonstantinou, Roth & Karakiulakis. 2012. Hyaluronic acid: A key molecule in skin aging. Dermatoendocrinol. Jul 1; 4(3): 253-258

 


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