We have seen some conflicting thoughts and opinions on hyaluronic acid lately, and really wanted to write something on the subject. Is it really that good of an ingredient? And what about the molecular size, isn’t it too big to penetrate the skin? The answer is yes, it is an amazing ingredient, and yes, it is too large to easily penetrate the skin. So how can it still be good for you?
What is hyaluronic acid?
First, lets go through what hyaluronic acid actually is. Hyaluronic acid is simply put a polymeric sugar molecule naturally found in our body, present in all tissues and fluids. As much as 50% of the hyaluronic acid in our body is found in the skin. Hyaluronic acid is the key molecule when it comes to skin moisture and is known for its ability to hold water up to 1000 times its own weight.
Hyaluronic acid is not only extremely hydrating but is crucial when it comes to tissue repair and wound healing in our body.
This is all amazing, but you may have heard that the molecular weight of hyaluronic acid is very high compared to what can easily penetrate the skin.
Hyaluronic acid and molecular weight
Molecular weight is measured in Dalton (Da). The highest weight that can fully penetrate the skin is 500 Da. Hyaluronic acid is usually of very high molecular weight, over 1 mDa, there is so called low molecular weight (LMW) hyaluronic acid, this is usually around 50-100 kDa, there’s also VLMW (very low) hyaluronic acid lower than 50 kDa, as low as 5 kDa. So why apply hyaluronic acid topically on the skin if it has difficulties penetrating the skin? Keep reading and we will tell you why.
Let’s simplify it - How does hyaluronic acid work in skincare?
To simplify, hyaluronic acid with high molecular weight does an amazing job at hydrating and soothing the skin. It has also shown positive effects on skin elasticity. Imagine having a hydration shield on top of your skin that continuously gives it water at the same time as it calms it down. As hyaluronic acid can hold large amounts of water, the water in your cream evaporates slower and stays on your skin for longer with the help of hyaluronic acid.
A well hydrated skin leads to a plumper and more radiant feel, which also has an effect on softening fine lines and making them less visible. If you are looking for a more long term anti-ageing effect and help to reduce wrinkles, LMW hyaluronic acid does the job better as it can “dig itself” a little deeper into the skin (check out “What does the science say about topically applied hyaluronic acid?” below for more info on this).
So remember, molecular size can be crucial, when you want the molecule to penetrate the skin, however all ingredients does not have to penetrate to give an effect! And if some of the studies gives any indication, you might not want the hyaluronic acid to penetrate below the top layer of the skin (keep reading the next section about what the science says to see for yourself).
If you are looking to boost your own hyaluronic acid production, adding hyaluronic acid in your skincare is not a solution, just like collagen in a cream cannot boost your own collagen production but it can moisturize and soften your skin instead. To boost your skins own production of hyaluronic acid there are other ingredients to help with that, such as different peptides or amino acids (same goes for collagen), but that’s a different blog post for the future!
What about our products?
In our Thirst Quench Activator Booster we use LMW (70 kDa) hyaluronic acid (sodium hyaluronate) and in Thirst Quench Hyaluronic Concentrate we use a mix of both high and low molecular weight for optimal hydration. On top of that all of our Thirst Quench products contains many more amazing ingredients to hydrate and soothe your skin. We want long term results and use several actives to boost the results even more, which is why we never rely on one ingredient to do the work alone.
Click here to see all products containing hyaluronic acid.
If you are curious for more information on hyaluronic acid and what has been found in different studies, keep reading (we are warning you though, it might get heavy!).
Structure of Hyaluronic Acid. Image borrowed from Wikipedia
What does the science say about topically applied hyaluronic acid?
Very Low vs Low Molecular Weight hyaluronic acid
Some evidence suggests that hyaluronic acid with molecular weight less than 20 kDa is involved in activating TLRs (Toll-like receptors) that is involved in activation of inflammatory cells, specifically TLR-4.
As kerationocytes express TLR-4, different LMW hyaluronic acids has been tested for an inflammatory response to determine a molecular weight threshold for application on the skin. Although this is based on only a few studies, evidence indicates that VLMW hyaluronic acid with a molecular weight of about 20 kDa contributed to the beginning of an inflammatory response. 50 kDa showed higher penetration rates than larger molecular weights (of over 300 kDa), but without showing any signs of proinflammatory activity.
Hydration and anti-wrinkle
It is well known that hyaluronic acid hydrates the skin. Many studies show noticeable moisturization and elasticity properties with high molecular weight hyaluronic acid. Whereas LMW hyaluronic acid has demonstrated reduction of wrinkles:
Analysis of interactions between hyaluronic acid and the stratum corneum has shown not only increased skin hydration, but also intense interactions between LMW hyaluronic acid (100 kDa) and the skin lipids. The same analysis also found that hyaluronic acid acted as an enhancer for delivery in normal skin, partly due to the increased skin hydration.
It has been found that LMW hyaluronic acid (despite the still large molecular size) provides better penetration abilities than larger sized hyaluronic acid and can influence the expression of several genes including keratinocyte differentiation and formation of intercellular tight junction complexes (These have been reported to be reduced in aged and photodamaged skin).
There was a study on 76 women to observe the efficacy of topical application of a formulation with 0.1% hyaluronic acid of different molecular weights (50, 130, 300, 800 and 2000 kDa) as an anti-wrinkle treatment. All formulations, regardless of the molecular weight of the hyaluronic acid led to significant improvement in skin hydration and elasticity. Whereas application of LMW hyaluronic acid was also found to significantly reduce wrinkle depth, most likely due to better penetration abilities.
Topical application of hyaluronic acid has in clinical trials been shown to improve wound healing.
In one study both venous leg ulcers and diabetic foot lesions has been shown to respond to hyaluronic acid treatment. So has acute radio-epithelitis in patients undergoing radiation therapy in a double-blind placebo-controlled study.
Another study showed positive impact on postoperative pain and burning sensation, and acceleration of palatal wound healing with topical application of hyaluronic acid, with both 0.2% and 0.8% hyaluronic acid gel.
Keep in touch!
Well done for getting all the way to the end! Was it too heavy and scientific? Or did you like getting into the details of an ingredient like this? Please let us know in the comments, or why not send us an email at firstname.lastname@example.org, maybe you have suggestions on what ingredient to write about next? Either way we would really appreciate your feedback!
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