Hyaluronic acid is a key molecule involved in skin hydration, and there are significant benefits from using sodium hyaluronate and hydrolysed hyaluronic acid in skincare formulas when its chosen correctly. Here’s some important facts about hyaluronic acid before you start formulating, as well as how to choose the right hyaluronic acid to get the best results for your cosmetic formulas…
1. The hyaluronic acid in your skin is not the same as the sodium hyaluronate in a cosmetic formula
The hyaluronic acid in your skin is a glycosaminoglycan substance found throughout the extra cellular matrix, that binds water strongly, to keep skin supple and hydrated. Most of the hyaluronic acid in a cosmetic formula, however, is in the form of sodium hyaluronate – a sodium salt of hyaluronic acid with better oxidative stability and a lower molecular weight than hyaluronic acid – making it much better to use in formulas for enhanced penetration and a better shelf life. Very low molecular weight forms of a raw material 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.
2. Hyaluronic acid and sodium hyaluronate applied to the skin do not reach the dermis
Regardless of the size or molecular weight, any sodium hyaluronate or hyaluronic acid that is applied topically does NOT penetrate through to the dermis. The pathway from topical application of these materials to deeper entry is blocked at the lipid-rich stratum granulosum1. Hyaluronic acid synthesized within the skin is trapped inside by the same lipid barrier, which helps to keep the skin hydrated. This means there is hyaluronic acid synthesized by the body within the dermis, held below the level of the stratum granulosum to keep moisture in the skin. There is also hyaluronic acid synthesised by the body above the stratum granulosum – this is more easily lost, but is the form that can be replaced with cosmetic products.
3. Hyaluronic acid production reduces as we age
When we are young, our skin makes plenty of hyaluronic acid present to bind water and keep our skin looking plump and feeling soft. As we age, the level of hyaluronic acid diminishes, and this contributes to drier, rougher skin as well as less supple, thinner looking skin.
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).
4. How hyaluronic acid size matters in cosmetic formulations
While the size or molecular weight of the sodium hyaluronate does matter to obtain specific benefits, to get the best results from your cosmetic formulas, the question is: what do you want it to do?
Very low molecular weight sodium hyaluronate will have deeper absorption to the stratum granulosum. This will not yield perceivable benefits for younger skin types, where there would already be plenty of hyaluronic acid made within the skin.
All skin types can benefit from high molecular weight sodium hyaluronate, because it creates a moisture protective film at the surface of the skin, to hold moisture in.
You can use a combination of both in your cosmetic formulas. 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 table to help you make the right hyaluronic acid selections for your cosmetic formulas based on skin needs and molecular weight:
|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|
5. Use the right amount of hyaluronic acid in your cosmetic formulas to get the best results
When it comes to hyaluronic acid and sodium hyaluronate, a little goes a long way. Using more in a cosmetic formula won’t necessarily get you better results, so use this guide to get your inputs right.
Sodium hyaluronate comes in one of two forms:
- powder – 100%w/w strength
- use all forms at inputs of 0.1 – 0.5%w/w for skin hydration benefits
- use high molecular weight powder at 2%w/w to create viscous, hydrating gels.
- watch how high molecular weights form beautiful gels with this video: hyaluronic acid gel with sodium PCA
- liquid – typically a 1%w/v solution
When adding to your formula, follow these rules:
- 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
When you choose the right molecular weight with the right input and right method, you will get the results you have been hoping for. Just remember skin physiology and the needs of your target market when making your selections and you’ll get the desired visible results fast.
1. Papakonstantinou, Roth & Karakiulakis. 2012. Hyaluronic acid: A key molecule in skin aging. Dermatoendocrinol. Jul 1; 4(3): 253-258
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Thank you Belinda for a very excellent article about my most favourite ingredient. Unfortunately, I have realised I’ve been using it wrongly (adding it to the water phase, therefore having it exposed to heat and high-shear). I cannot figure out: what is then the best way to incorporate HA if I make a cream with a homogeniser?
I am thinking I could make a gel with say 1% HMW HA and 1% LMW HA and add it to the end phase while stirring by hand, but I am afraid that more than a few percent of a water-based ingredient might destabilize the product… Or would it be better to add it to the end phase as part of a glycerine slurry? Thank you so much for all the work you do, I very much appreciate it, you are an amazing teacher & cosmetic chemist.
Thanks Uma, we have passed on your comments / questions to Belinda!
Hi Una, the response form Belinda is:
You would normally only need 0.1 – 0.5%w/w of the powder, and this can easily be added at the end, after the emulsion has cooled. Just ensure thorough low shear stirring for it to hydrate homogenously. Happy formulating!
Thank you very much for the answer, Belinda and Ivan. Much appreciated!