Hyaluronic acid (HA) or sodium hyaluronate is a common ingredient in skincare that is often misunderstood. HA is a natural polymer that plays several critical roles in keeping skin healthy. It is important to know that not all HA is created equal and its role as an ingredient in skincare products is frequently misrepresented.
First, some background information:
- HA is a string of sugar molecules that coil up to fill space in the skin (i.e., plump the skin). Let us briefly explain – HA is a repeating unit (i.e., polymer) of two sugar rings bonded together (think of a figure 8). When coiled up, HA physically supports the natural collagen matrix (structural backbone of the skin), increasing skin’s volume and fullness.
- HA is famously thought of as a sponge due to its ability to hold water. Attached to the edges of each sugar ring are several chemical functional groups that are acidic in nature and highly charged. This allows them to easily bond with and hold onto water.
- The key to HA’s functionality within the skin is the length of the string of sugar molecules (the length of repeating figure 8’s). This length determines the molecular weight of the HA. A very long string can more easily coil up to increase skin’s volume and decrease the appearance of wrinkles. But therein lies the rub—the longer the string, the less likely it is to be absorbed through the skin.
So why is HA in so many skincare products?
HA is desirable because it is a water-absorbing, natural polymer that feels great against the skin. High molecular weight strings of HA, although not able to penetrate the skin, serve as a moisture barrier by retaining water and keeping the skin from drying out. HA can also be used to replace synthetic fillers such as silicone enabling skincare companies to make healthier, more effective skincare alternatives.
What most consumers don’t know:
There are shorter HA strings (low molecular weight) which are much easier and cheaper to manufacture – and this less expensive HA is often falsely advertised as skin plumping. Shorter string HA molecules found in many skincare products are more likely to penetrate the skin, but do not effectively coil up and plump the skin — hence why not all HA is considered equal (there is a reason HA fillers are injected into the skin with a needle!).
Healthy, nourished skin has the ability to produce HA naturally. In part 2 of this series, we will delve further into the biological role of HA in the skin, and its relationship to your health.