How hyaluronic acid works

Hyaluronic acid is naturally present in our body and has a molecular weight of 4000 to 8,000,000 daltons. In cosmetics, there are different types of hyaluronic acid that can be used in cosmetic formulations. And they vary based on their molecular size and their effects can vary based on the molecular size that is indicated by its daltons. Hyaluronic is typically labelled as sodium hyaluronate (INCI = Sodium Hyaluronate) and thus doesn’t outline the different molecular sizes that a manufacturer is using. It is at the discretion of the brand to be transparent about the type of sodium hyaluronate it is using. Again, type in relation to the molecular size which has different effects on the skin. If you want to find out which Hyaluronic Acid a brand is using you need to ask the brand about the specifics so you get the result you are looking for.

Once it sinks into skin, hyaluronic acid can hold up to 1,000 times its weight in water — and in doing so gives skin a soft, plumper texture and more even skin tone. It can improve fine lines and wrinkles as well. On top of that, hyaluronic acid is gentle on the skin barrier, making it a good choice whether you have dry or dehydrated skin.

Why size matters

But not all hyaluronic acid molecules are created equal. In fact, there are six different sizes. Different molecular weights penetrate to different levels of the skin. Molecules with lower molecular weight are smaller, and can therefore reach the deeper layers of skin. There, they sustain skin’s moisture content. Those with high molecular weights, on the other hand, remain closer to the surface, where they can deliver the most visible results with a shorter life-span. As the results will be washed away with the next cleansing ritual.

Roughly, we distinguish between 2 molecular sizes: high molecular weight hyaluronic acid and low molecular weight hyaluronic acid. However, there are more specific ones that you can see below outlined in the table. 

Below is a table to outline the different molecular sizes Sodium Hyaluronate can represent and its effect:

Type of HA

Molecular weight (in Dalton) kDA

Use

High molecular weight >1.800.000 <1.800 –       works only for a short time

–       forms a moisturizing film on the skin surface

–       has anti-inflammatory effects

Middle molecular weight 1.000.000 to 1.800.000 1000 – 1800 –       is stored in the connective tissue of the skin

–       works long term

Low molecular weight 400.000 to 1.000.000 400 – 1000 –       works long term

–       is stored in the connective tissue of the skin

–       has a lasting anti-wrinkle effect

S 100.000 to 400.000 100 – 400 –        Works in deeper levels of the skin
XS <100.000 >100 –        Regenerating