Hyaluronic Acid Is Overrated Part 3: Hyaluronic Acid In Depth And Conclusion
By: Yasmeen Naseer
Tags: Hyaluronic Acid, Skin Care Products, Skin, Skincare, Beauty

One source of the hyaluronic acid found in cosmetics is the rooster comb.

Did you know that the hyaluronic acid in your serum might have come from those red flappy things attached to the face of a rooster? They’re called rooster combs and contain the popular cosmetic ingredient in abundance. In cosmetics it’s used as a humectant and usually marketed as being able to hold a thousand times its weight in water — which while true when the molecule is inside the skin, is debatable when it’s topically applied, but more on that later. It is able to bind water due to the abundance of hydroxyl groups on the molecule, as explained in part 1 of this series, and occurs naturally in the human body where, among other things, it cushions and lubricates the joints.

In the skin hyaluronic acid is the main component of the extracellular matrix — the collagen and elastin fibres, among other things, that hold the cells of a tissue in place and give the tissue its structure. Most of the skin’s hyaluronic acid is concentrated in the dermis and decreases as we move up the layers of the epidermis towards the stratum corneum — the outermost layer of the skin that’s visible to us — and is only abundant on the skin’s surface in the event of wound healing, a process in which hyaluronic acid plays a key role. Hyaluronic acid helps give skin its structure and keeps it plump and hydrated. Just like collagen and elastin, it also decreases in our skin as we age, making ageing skin more susceptible to volume loss, dryness, sagging, and wrinkles.

In addition to extraction from animal tissues like rooster combs, hyaluronic acid can also be biosynthesised using microorganisms — where the microorganism used has an impact on the quality of the end product. Hyaluronic acid produced using Streptococcus bacteria for instance, has the potential to be contaminated with endotoxins — substances bacteria produce that are toxic for humans. However, new, safer methods of production are being developed given the compound’s popularity not just in cosmetics, but also in pharmaceutical and biomedical products.

In cosmetics, hyaluronic tends to be used in one of two ways: topically, or as in injectable — think dermal fillers, but in this post I’ll limit my discussion to its use in the former. Two key myths around its topical use abound: first, that it’s an exfoliant, which people assume because of the presence of the word acid in the name, and second, that it’s an anti-ageing ingredient. Both are not true — hyaluronic acid is a humectant. While essential for skin health when it’s inside the skin, its molecules are too large to be absorbed when it’s applied topically. Topical application can at best, hydrate the skin’s surface so it appears plumper, and fine lines get smoothed over — but the effect is temporary.

Smaller molecules of hyaluronic acid do exist and were developed by scientists for increased skin penetration. They tend to be more expensive and are often highlighted on cosmetics packaging for this reason. However, while they are able to go relatively deeper into the skin, they don’t bind as much water and unlike their high molecular weight counterparts, low molecular weights of hyaluronic acid have also been associated with skin inflammation and irritation, where the smaller the molecule, the greater the irritation.This is because lower molecular weights trigger an immune response and might also be problematic because they cause other ingredients, irritants included, to go deeper into the skin which is especially problematic if your skin barrier is compromised. However, even low molecular weight hyaluronic acid isn’t able to penetrate too deep and only a small fraction tends to make it to the base of the epidermis.

Only a small fraction of low molecular weight hyaluronic acid molecules make it past the stratum corneum — the topmost layer of the epidermis that’s visible to us — down to the base of the epidermis. This illustration also shows components of the skin’s extracellular matrix, mentioned earlier. These include hyaluronic acid, collagen fibers, and elastin fibers.

A number of people who’re using hyaluronic acid and have a “good” skincare routine but still have skin irritation for reasons that they’re unable to grasp, see marked improvement once they cut the hyaluronic acid out. As Harper’s Bazaar nicely summarises:

“Editors and Redditors alike have written about the redness and dryness they believe to be caused by topical HA. Instagrammers and influencers have eliminated it from their routines, with impressive results. The Mixed Makeup Facebook group recently held an “HA-free” challenge, with hundreds of comments detailing individual HA sensitivities and reporting improvements. One-star reviews of popular HA serums point to extreme irritation, beauty brands have issued usage warnings for their HA-laced products, one medical-grade HA ointment advises patients that “prolonged use may give rise to sensitisation phenomena,” and hyaluronic acid injectables are increasingly associated with late-onset inflammation.

Mary Schook, an aesthetician and cosmetic formulator, is among the first industry professionals to take note of all of the above. “A client had an immediate reaction to something [during a treatment] and I was like, ‘What’s going on here?’’ she tells BAZAAR. “The product had three different molecular weights of hyaluronic acid in it.” The incident inspired years of research, trial, and error and today, Schook recommends that her clients remove HA from their routines completely. “I find it to be the one common ingredient that I ask consumers to quit and 98 percent of them have symptoms’’ — redness, dryness, texture issues, breakouts, dermatitis, rosacea, and more — “that subside.””

While high molecular weight hyaluronic acid has been shown to have an anti-inflammatory effect, even with that, it’s easily possible to go wrong with it. It’s strong water binding capabilities mean that if you use too much, it’ll pull more water upwards from the skin’s deeper layers where it’ll be easier for it to evaporate making your skin more, not less, prone to dehydration and the issues that follow. One leave-on product that contains HA is more than enough in your routine and how you use it also matters — it’s best applied on wet or damp skin and then followed up with a heavy moisturiser to help seal the hydration in.

And here’s where things get really interesting. I mentioned in the beginning that hyaluronic acid is known to be a potent humectant that is usually marketed as being able to hold up to a thousand times its weight in water. However, while this may be true of the version of the substance that’s found in our bodies, there’s no evidence to prove that the hyaluronic acid found in cosmetics is able to do that and according to a video by Stanford Chemicals Company, a hyaluronic acid manufacturer, topical hyaluronic acid has limited ability to retain water, and this ability also depends on the size of the molecule in question. A lawsuit was also filed against Peter Thomas Roth’s Water Drench line in this regard. According to The Fashion Law:

The plaintiffs assert that in connection with its “Water Drench” line of products Roth “represents that the active ingredient, hyaluronic acid, will draw moisture from the atmosphere into the user’s skin, and will hold 1,000 times its weight in water for up to 72 hours.” This is impossible, they claim, as “hyaluronic acid is incapable of absorbing anywhere near 1,000 times its weight in water, even when it is in its anhydrous (i.e., waterless; completely dry) form.”

And according to the files of the case, “This outlandish claim [that hyaluronic acid can hold up to a thousand times its weight in water], is entirely unsupported by science. Published data from actual studies by real chemists establishes that hyaluronic acid binds a small amount of water, equivalent to about half the weight of the hyaluronic acid, or between 9 and 19 molecules.” In this regard, the judge ruled in favour of the plaintiff.

In physiological systems however, hyaluronic acid is generally able to hold on to over a 1000 times its weight in water, something that has to do with its high molecular weight, large molecular volume, entangled structure and extensive interaction between hyaluronic acid chains in such systems, properties that likely don’t hold when hyaluronic acid is deployed in a cosmetic product.

What About Sodium Hyaluronate?

Often when you find hyaluronic acid advertised on a product, the ingredients list contains sodium hyaluronate instead. Hyaluronic acid tends to be an umbrella term used for all molecular weights of hyaluronic acid and sodium hyaluronate, its sodium salt. Sodium hyaluronate is also found naturally in the body. In fact, under physiological conditions in the human body, hyaluronic acid tends to exist as sodium hyaluronate, but the structure is sensitive to ion concentration and pH.

Sodium hyaluronate exhibits similar properties as hyaluronic acid. However, it is more bioavailable and therefore, more readily absorbed into the skin. It’s also less prone to oxidation and able to maintain a longer shelf life. Like hyaluronic acid, it’s also available in different molecular weights, where heavier weights deliver surface hydration and lower weights are able to go deeper into the skin.

The Verdict

Hyaluronic acid has become an extremely popular humectant. Interest in the ingredient has quadrupled over the last decade according to Google Trends data, and this is despite its fairly complicated name. Anyone moderately interested in skincare is aware of what it is and companies are racing to fulfil demand by making hyaluronic acid serums and adding the ingredient to just about every product so that they can advertise it on the label. However, hyaluronic acid falls short of the all hype it gets for several reasons.

Evidence doesn’t support the claim that topically applied hyaluronic acid is able to hold up to a thousand times its weight in water.

High molecular weight hyaluronic acid — the good kind — simply sits on top of your skin and there isn’t enough evidence to show that it draws water from the atmosphere — and not your skin’s deeper layers — to help keep your skin hydrated. In fact, a 2018 study funded by Estée Lauder found that in humid environments hyaluronic acid made the skin look temporarily hydrated but actually had to opposite impact and increased transepidermal water loss. And a 2016 study found that low molecular weight hyaluronic acid also increased water loss by over 55%.

Hydrolysed, i.e., lower molecular weight, forms — which tend to be advertised on cosmetic packaging when they’re used, due to their higher costs — can go deeper but are associated with skin irritation and the lower the weight, the higher the potential for irritation.

It’s not all bad news though and there is evidence from multiple studies to suggest that hyaluronic acid aids in wound healing. As a humectant though, I simply don’t believe that it’s the gold standard that it’s made out to be and several other wonderful humectant options, such as glycerin, urea and panthenol, do exist as I discussed in part 2 of this series.

If you still want to try incorporating hyaluronic acid into your routine, or if you’ve been using it already and feel like it works for you, make sure that you use it right — since everyone’s response to an ingredient is not the same, across the board. But don’t use it if you’re young and your skin is already functioning well. But if you’re not, and are looking to try it for skin hydration, here’s how to use it.

Look for products that have a maximum concentration of 1% — in fact, lower concentrations of up to 0.5% might actually be better. Higher percentages can dehydrate the skin by pulling water up from deeper layers and allowing it to evaporate more easily from the surface. Give preference to higher molecular weights and limit the number of products that you’re using that contain the ingredient to just one. Avoid using it at all in dry climates and when you do apply it, apply it on damp skin and follow up with an occlusive moisturiser to seal the hydration in.

And of course, why try applying it topically at all when you can instead focus on trying to boost your skin’s own production of the ingredient. A considerable amount of evidence exists to suggest that oral hyaluronic acid supplementation is able to relieve the symptoms of dry skin. Some ingredients in skincare that increase cellular turnover, which slows down as the skin ages, might also help increase the production of hyaluronic acid since each new cell that’s made adds to the skin’s extracellular matrix — which is where hyaluronic acid is found. Cellular turnover can be increased by adding retinoids and chemical exfoliants like glycolic acid, lactic acid and salicylic acid, to your routine. And it also never hurts to have a good diet rich in good fats and leafy greens.

While this isn’t a comprehensive list of how you can boost your skin’s own hyaluronic acid production, and research in the domain is ongoing it’s a start that’s likely to yield some truly powerful results.

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