Hyaluronic Acid is an oldie in skincare but seems to never be out of fashion. This elusive ingredient has been tied to so many different types of skincare benefits ranging from hydration claims to anti-anging claims. Add on the fact that hyaluronic acid serums also come with a wide range of price tags (think sub $10 to $400…?!) plus some concerns around HA causing skin dehydration and presto! Much confusion about hyaluronic acid!
But, not to worry. In this guide, we’ll tackle what this ingredient actually does for skin topically, address the concerns around hyaluronic acid causing dry skin, discuss which hyaluronic acid is best for your skin goals, and ultimately how to shop for hyaluronic acid like a chemist!
What is Hyaluronic Acid?
Hyaluronic acid (HA) is a polysaccharide that is formed with repeating chains of glucuronic acid and acetylglucosamine. Typically HA is a very long-chain polymer in skincare that functions as a humectant with a unique capacity to hold on to a lot more water. This is the ingredient you’ll often hear that is claimed to hold “1000x its weight” in water.
As we mentioned before, there’s a lot of confusion around what hyaluronic acid does as a skincare ingredient because hyaluronic acid is not just a skincare ingredient, it's a molecule that’s naturally found in our skin. In our skin, HA plays a variety of important functions from maintaining our skin tissue’s homeostasis, being responsible for robust cell structure (think plump and firm!), and acting as a signaling molecule for healthy skin function.
*Fun fact! The HA in our skin is produced and broken down daily and has a half-life of about a day.
However in skincare, hyaluronic acid seems to be tied to a wide range of product claims such as improving skin hydration, plumping skin, and even anti-aging ones like reducing wrinkles. This wide range of claims can cause a lot of confusion around just what hyaluronic acid does for your skin. If you dive down the HA rabbit hole a bit more, you’ll see that a lot of these different claims are associated with different “molecular weights” of hyaluronic acid. So… ii there an optimal topical hyaluronic acid size you should be targeting in your serum hunt?
What is the Best Hyaluronic Acid For My Skin?
Hyaluronic acid size in skincare can range from huge polymers that are 2000 kDA (typically tied to hydration claims, featured in our Aquafix) to as small as 50 kDa (typically tied to anti-aging claims). But is it truly this clear cut? Well, we have to highlight one very thorough study that wanted to answer this precise question.
One clinical study wanted to compare 5 hyaluronic acids of different molecular weights (50, 130, 300, 800, and 2000 kDa) at 0.1% in a cream base. Study participants were evaluated in terms of skin hydration, elasticity, wrinkle depth, and skin roughness. An awesome comparison! They tested these HAs, plus a control cream, on 76 female subjects between the ages of 30-60 years of age with clinical signs of wrinkles. Subjects applied the topical cream with the designated hyaluronic acid formula on the periocular eye area for 2 months.
After 2 months, results were not that straightforward! They found significant improvement in skin hydration for all molecular weights except for the 50kDa. All molecular weights showed significant improvement in skin elasticity (think bounce, plump, etc,) after just one month. 130 kDa hyaluronic acid was the only one to show significant improvement in skin roughness after two months of use. 50 kDa was the only one to show significant improvement in wrinkle depth around the eye area.
Based on these results, some general takeaways are that hyaluronic acid generally does contribute to a plumping effect. The lowest molecular weight HA (50 kDa) can provide wrinkle-fighting benefits. However, hydration benefits are not as clear-cut. Turns out that the improvement in skin hydration for 2000, 800, 300, and 130 kDa hyaluronic acid was 2.9%, 5.1%, 13.8%, and 9.8% respectively. This means that just because an HA is bigger in size doesn’t necessarily mean you’ll get improved hydration benefits, Size doesn’t always matter…heh heh heh.
Keep in mind that despite this paper having a larger test size, splitting the subjects into the 6 subgroups of different HA sizes means a pretty small data set in each group. However, it is interesting to note that choosing hyaluronic acid based on molecular weight is not that straightforward.
Confusion Corner: “I heard hyaluronic acid causes dry skin! Is this true?”: There is a train of thought that hyaluronic acid can cause water to evaporate out of skin leading to skin dehydration and dry skin. As you can see from the study shared above, HAs of various molecular weights aside from the lowest molecular weight hyaluronic acid when put in a cream base was still found to significantly increase hydration. However, remember that hyaluronic acid is a humectant (a water-based molecule), which means when formulated in a water serum does not have ingredients that will prevent moisture from evaporating from skin.
All in all, based on available data, there isn’t one “BEST” hyaluronic acid size you should be targetting. The main takeaways we’d say are:
- 50 kDa is the size you should be looking for when shopping for true “anti-aging” hyaluronic acid
- Size doesn’t (quite) matter when it comes to hydration. Most hyaluronic acid serums you see on the market will have the larger size.
How to Shop for Hyaluronic Acid
As chemists, we believe hyaluronic acid truly functions as a moisturizing ingredient that provides a plumping effect because of its inherent nature as a humectant. We would advise not to take overly exaggerated claims of HA too seriously outside of the hydration realm. As an anti-aging ingredient, this ingredient’s efficacy really depends on the source so we recommend seeking out brand testing to give you a better sense of efficacy.
How to Shop for Hyaluronic Acid for Hydration
Hyaluronic acid has really snuck into a lot of products so chances are you probably already have it somewhere in your routine. So step one is actually to do a quick ingredient list scan to see if it’s already in your routine. If you do then great! Your HA needs are covered!
If you’re trying to add in hyaluronic acid you’ll find hundreds of HA serums of all different price points. The goal is NOT to buy single-ingredient HA serums, because we feel this can take up precious space in your routine. Instead, look for serums that come with blends of humectants such as glycerin, NMFs, and panthenol. Get more! Remember that the best humectant strategy is a blend of different ingredients since each comes with their own unique benefits. This is why our Aquafix Water Gel comes with a whole resume of carefully put-together humectants. Check out our this vs. that mapping for examples on how to shop for your next HA product!
How to Shop for Hyaluronic Acid for Anti-Aging
Hyaluronic Acid as an anti-aging ingredient can be hit or miss because it can really be ingredient source dependent. We highly recommend looking for any clinical testing to get a better sense of performance. This category can have some astoundingly high price tags so testing is key! Skinceuticals HA Intensifier is a good example of an anti-aging HA serum that comes with interesting clinical evidence.
Should You Shop Based on Hyaluronic Acid Concentration?
This category can get pretty crazy with percentages! However, it doesn’t take a lot for hyaluronic acid (excluding the low molecular weight size) to turn into a big gel block. Think roughly >1% to get your HA jello. But wait! If you browse the hyaluronic acid shopping pages, sometimes you can find 100% Hyaluronic Acid gels. What gives? These large %s are a bit misleading. Remember how hyaluronic acid can hold up to “1000x its weight” in water? These 100% hyaluronic acid water gels are simply hyaluronic acid already “pre-swelled” (aka. Pre-soaked in water). The actual concentration of HA is much much lower than the advertised 100%, otherwise, you’d be getting a powder product.
In terms of actual concentration to look for, you actually don’t need a lot to obtain those great hydration benefits. We’re talking as low as 0.1%, which means we don’t have to hone in on HA concentrations too much in our skincare.
Takeaways & Where Does Hyaluronic Acid Go In Your Skincare Routine
Ultimately remember that hyaluronic acid is one of many humectants out there! We all need more than one humectant to get the most out of the hydration category. Not to mention, we need more than just humectants to have a complete moisturizing strategy (check out our moisturizer ingredients decoded blog post!). This is why we find single-ingredient hyaluronic acid serums to ultimately be a waste of space in your skincare routine. Finally, most hyaluronic acid serums are water-based serum textures, so we recommend using these in the beginning steps of your routine.
References
Eleni Papakonstantinou, Michael Roth & George Karakiulakis (2012) Hyaluronic acid: A key molecule in skin aging, Dermato-Endocrinology, 4:3, 253-258, DOI: 10.4161/derm.21923
Abatangelo, G.; Vindigni, V.; Avruscio, G.; Pandis, L.; Brun, P. Hyaluronic Acid: Redefining Its Role. Cells 2020, 9, 1743. https://doi.org/10.3390/cells9071743
Pavicic T, Gauglitz GG, Lersch P, Schwach-Abdellaoui K, Malle B, Korting HC, Farwick M. Efficacy of cream-based novel formulations of hyaluronic acid of different molecular weights in anti-wrinkle treatment. J Drugs Dermatol. 2011 Sep;10(9):990-1000. PMID: 22052267.
