Hyaluronic Acid

AKA: Hyaluronan
A potent, skin-identical humectant moisturizing ingredient that is able to bind water 1000 times its own weight. The anti-aging benefits of hyaluronic acid are due to its ability to stimulate the synthesis of collagen in the skin.
Also-Known-As:
Hyaluronan
All functions
Origin
Hyaluronic Acid

Overview

If you’re interested in skincare, then you’ve definitely everyone heard about Hyaluronic acid, one of the best humectant moisturizing ingredients on the market.

You will have the chance to learn a little more about this amazing ingredient in this article, and see what the current dermatological sciences have to say about its numerous properties and uses.

Let’s begin by discussing what hyaluronic acid is and what it looks like. It is a skin-identical ingredient because your skin actively produces in its dermis (the middle layer of skin). This is where it acts as a sponge and binds and holds large amounts of water – reportedly up to 1000 times its own weight.

Hyaluronic acid is such an important ingredient because it is a close companion to collagen and elastin, the structural elements of the skin. It holds them in proper configuration and maintains their elasticity and strength.

It is also one of the main components of the extracellular matrix, the scientific name for the thick liquid that fills the spaces between the cells of the body.

The ingredient has viscosity controlling properties, meaning that if you touched a hyaluronic acid solution, it would feel very slippery and gel-like.

Before we move on to its many benefits, let's have a look at its chemical composition (yeah – time to get technical). Hyaluronic acid belongs chemically to the family of glycosaminoglycans (along with glucosamin, chondroitin, and keratin - other gel-like structural molecules).

It is a truly massive molecule, consisting of glucuronic acid and acetylglucosamine. The two form a unit that is repeated over and over, up to 10 000 times or more.

Depending on the number of these units and the size of the hyaluronic acid molecule (measured in Daltons, Da) we can distinguish between High Molecular Weight hyaluronic acid (HMW, cca. 1000 kDa and more), Low Molecular Weight hyaluronic acid (LMW, 10-1000 kDa) and so-called Nano-HA (smaller than 10 kDa). These numbers may vary depending on the source.

You may be asking an important question: what is the difference between sodium hyaluronate and hyaluronic acid? The results are unsurprising.

Although there seems to be a lot of false information floating around on the internet, scientific studies suggest that there is no real difference between sodium hyaluronate and hyaluronic acid.

In fact, the two terms are often used interchangeably. Sodium hyaluronate is a simple sodium salt of pure hyaluronic acid, and it happens to be slightly more stable, more practical, and cheaper to produce. When comparing their humectant and anti-wrinkle effects, it actually depends more on the molecule size of the compound than the presence or absence of sodium.

Although it is called an acid, it is important to note that hyaluronic acid does not belong to the group of Alpha-Hydroxy Acids (AHAs).

Now we get to the important part. How does hyaluronic acid work, and what are its benefits? Considering that it has such a large molecule, can we even be sure that it penetrates the skin? Several studies have tried to answer this very question.

One compared the efficacy of several 0.1% hyaluronic creams with different molecular weights. It was found that LMW hyaluronic acids resulted in better skin hydration, elasticity, and anti-wrinkle effects. The 50 and 130 kDa hyaluronic acids produced the best results, although even the 2000 kDa hyaluronic acid resulted in improved skin hydration.

Another study found that the 5 kDa hyaluronic acid definitely penetrated the skin, taking other water-soluble compounds with it. Overall, the studies agree that LMW hyaluronic acid is able to penetrate the skin and offer anti-wrinkle benefits, whereas HMW hyaluronic acid acts as a surface-layer humectant.

The HMW hyaluronic acid is better suited for microneedling or filler injections, because it more closely resembles the original hyaluronic present in the skin.

The anti-aging effects of hyaluronic acid not only stem from the improved hydration, but also from hyaluronic acid’s ability to stimulate the synthesis of collagen in the skin. It is often used in the treatment of very dry or damaged skin, such as seasonal eczema or psoriasis.

In people with rosacea, 0.2% hyaluronic acid can help to soothe the red, inflamed patches. It has been proven through a human trial that hyaluronic acid can help to calm down overreactive sebum glands, making it a suitable ingredient for oily and acne-prone skin.

It is also slightly anti-inflammatory and displays subtle antioxidant properties.

Only hyaluronic acid injections have been tested on acne scars so far, and they were found to be very beneficial. Similarly, only the injections have been tested on under-eye bags and thin and cracked lips, and so we are uncertain as to whether a hyaluronic cream may help with this.

You’ll be glad to hear that the rules of application of hyaluronic acid are simple. There have been almost no reports of skin irritation, except in the case of the injections. This, however, is easy to understand, as injections are far more invasive than a cream.

Some test-tube experiments suggest that LMW hyaluronic acid and very small hyaluronic acid fragments may actually be pro-inflammatory, because they make the skin cells believe that something is damaged and falling apart. This, however, has not been confirmed on living skin, and so it is more or less just speculation.

Hyaluronic acid is safe to use during pregnancy and can even be used to prevent stretch marks.

It has been shown in clinical studies that the lowest effective concentration of hyaluronic acid in a skincare product is around 0.1-0.2%. Clinical trials also confirm that it can be used twice a day without issue. Depending on which study you believe, the time necessary to see the first beneficial results is somewhere between two weeks, and two months.

Incredibly, hyaluronic acid is safe to use with any other ingredient. So far, there are no known ingredient combinations with hyaluronic acid that would be particularly damaging.

Science

1
Bukhari, S.,et al. (2018). Hyaluronic acid, a promising skin rejuvenating biomedicine: A review of recent updates and pre-clinical and clinical investigations on cosmetic and nutricosmetic effects. International journal of biological macromolecules, 120(Pt B), 1682–1695.
2
Pavicic, T., et al. (2011). Efficacy of cream-based novel formulations of hyaluronic acid of different molecular weights in anti-wrinkle treatment. Journal of drugs in dermatology : JDD, 10(9), 990–1000.
3
Witting, M., et al. (2015). Interactions of hyaluronic Acid with the skin and implications for the dermal delivery of biomacromolecules. Molecular pharmaceutics, 12(5), 1391–1401.
4
How, K. N., Yap, W. H., Lim, C., Goh, B. H., & Lai, Z. W. (2020). Hyaluronic Acid-Mediated Drug Delivery System Targeting for Inflammatory Skin Diseases: A Mini Review. Frontiers in pharmacology, 11, 1105.
5
Schlesinger, T. E., & Powell, C. R. (2013). Efficacy and tolerability of low molecular weight hyaluronic acid sodium salt 0.2% cream in rosacea. Journal of drugs in dermatology : JDD, 12(6), 664–667.
6
Jung, Y. R., et al. (2017). Hyaluronic Acid Decreases Lipid Synthesis in Sebaceous Glands. The Journal of investigative dermatology, 137(6), 1215–1222.
7
Dierickx, C., Larsson, M. K., & Blomster, S. (2018). Effectiveness and Safety of Acne Scar Treatment With Nonanimal Stabilized Hyaluronic Acid Gel. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 44 Suppl 1, S10–S18.
8
Korgavkar, K., & Wang, F. (2015). Stretch marks during pregnancy: a review of topical prevention. The British journal of dermatology, 172(3), 606–615.
9
Jegasothy, S. M., Zabolotniaia, V., & Bielfeldt, S. (2014). Efficacy of a New Topical Nano-hyaluronic Acid in Humans. The Journal of clinical and aesthetic dermatology, 7(3), 27–29.