‘Hyaluronic Acid’, ‘HA’, ‘Hydration Ingredient’, we’ve heard it all in the cosmetic adverts. It seems like nowadays, there isn’t a single cosmetic out there without the addition of hyaluronic acid. Why is it so popular?
In this article we will delve into what HA is on a molecular level, its function and mechanism of action. Finally, we will answer the question: ‘Is hyaluronic acid really worth the hype?’
Cosmetic Ingredients Series
Below is a list of the most recent articles about cosmetic ingredients, to view the full list, click here.
What is hyaluronic Acid?
Hyaluronic acid, commonly shortened to HA, is a common skincare ingredient. It falls under the category of a humectant, which are ingredients which draw moisture to the site. HA is commonly referred to as the ‘skin hydration ingredient’ in the market space and has gained a great reputation within the skincare world. This is a water-soluble ingredient present in almost every skincare preparation.
HA is a glycosaminoglycan, which are simply long unbranched carbohydrates, or sugars, called polysaccharides. They are found throughout the body where their elasticity and humectant (water drawing & retention) properties are put to use.
HA can be referred to as a biomimetic ingredient. Biomimetic simply means to mimic (or imitate) nature and its biological processes.
HA is a bio-equivalent biomimetic ingredient because it has the same exact chemical structure in the bottle as it does in your skin. Bio-equivalent ingredients are more likely to be animal-derived, but most hyaluronic acid in products you’ll find will be synthetically produced or produced by bacteria fermentation, so you don’t have to worry about ethical concerns when using this ingredient.
Where is HA found in the skin?
HA is found in the intercellular matrix, most notably the papillary (upper) dermis, but is also abundant in the reticular (main) dermis. HA is also present in epidermal layers below the stratum granulosum.
Below is an image of the skin structure, with a zoom-in of the epidermis. HA is abundant throughout the skin, with the exception of the stratum lucidum and stratum corneum, as these parts of the skin function as the main barrier and are strictly hydrophobic (do not contain any water).
HA is most abundant in the skin, accounting for 50% of the total hyaluronic acid found in your body. It comes in many different forms depending on their size. Different chain lengths of hyaluronic acid provide them with different properties. Long-chained hyaluronic acids, for example, are used for the lubrication of joints. The HA found in your skin are the shortened chain lengths.
How is HA made in the skin?
This substance is produced primarily by mesenchymal cells but also by other cell types. HA is synthesised by specific enzymes called hyaluronic acid synthases (HAS). These are membrane bound enzymes that synthesise HA on the inner surface of the plasma membrane and then HA is extruded through pore-like structures into the extracellular space. There are three mammalian enzymes HAS -1, -2 and -3, which exhibit distinct enzymatic properties and synthesise hyaluronic acid chains of various lengths.
HA chemical structure
HA polymers occur in a vast number of configurations and shapes, depending on their size, salt concentration, pH, and associated cations. Unlike other GAG, HA is not covalently attached to a protein core, but it may form aggregates with proteoglycans.
HA is a non-sulphated GAG and is composed of repeating polymeric disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine linked by a glucuronidic β (1→3) bond. In aqueous solutions hyaluronic acid forms specific stable tertiary structures. Despite the simplicity in its composition, without variations in its sugar composition or without branching points, hyaluronic acid has a variety of physicochemical properties.
What are Humectants?
Humectants are molecules which have an affinity for water. They are able to draw neighbouring molecules of water into/on their structures. This means they can attract water from deeper parts of the superficial fascia into the dermis and some will claim that it can even draw moisture from the environment into the skin… but I struggle to believe that considering the lack of evidence.
In other words, humectants help keep your skin hydrated. Skin hydration plays a key role in skin health, most importantly, it’s a substrate in an abundant number of chemical processes going on in your skin. Secondly, it provides suppleness, flexibility and elasticity to the skin, but more on that in the benefits of hyaluronic acid section.
hyaluronic acid mechanism of action
Due to hyaluronic acid’s highly anionic properties, it can attract water to swell and create volume and provide structural support. HA molecules can attract up to 1,000 times their own weight in water.
Water is a polar molecule. Water has an oxygen molecule, and two hydrogen molecules (H₂O). Not all atoms are the same, and in this case, the oxygen in water has a strong positive nuclear charge (+) relative to the nucleus of the hydrogen atoms. Electrons are negatively charged (-) and are attracted to positive things. Because the positive attraction of the oxygen’s nucleus is stronger, the electrons of the neighbouring hydrogen atoms are attracted to it, drawing the electrons closer to the oxygen’s nucleus.
This creates a polar molecule, with two positively charged sites and one negative charged site. HA is an anionic molecule (negatively charged) and because water has two positively charged sites, it takes advantage of that to form hydrogen bonds with water – equalising the charges (become more neutral).
Because water molecules have a smaller molecular weight (they are lighter), the water migrates to the hyaluronic acid instead of the other way around. This is how HA is able to attract water molecules. With an increase in water molecules in the dermis, it creates a ‘filler’ effect, which translates to the many benefits hyaluronic acid offers.
The benefits of hyaluronic acid
The internet and adverts will tell you that there are so many benefits to using HA, which is true – but all of the benefits are actually just one benefit given many different names.
Improvement in Skin Elasticity, Volume & Texture
As previously mentioned, HA attracts water molecules to the site. If you imagine your skin as a bean-bag, the more styrofoam balls are in the bag, the more volume-ous it becomes, the more elastic the outside feels and there are seemingly less wrinkles in the bean-bag.
Your skin is exactly the same, but replace ‘styrofoam balls’ with ‘water molecules’ and the ‘bean-bag material’ as your skin.
By simply increasing the water content within the dermis, the skin looks and feels healthier, more elastic, less textured and some even report reduction in fine lines and wrinkles. It can be viewed as a topical ‘skin filler’ (although Hyaluronic Acid skin fillers are certainly a thing) which fills your skin with water.
Why is hyaluronic acid so popular?
You can shout about the benefits of hyaluronic acid from the rooftops, and many cosmetic brands have taken that a little too literally. Hyaluronic’s popularity in the cosmetics industry was fuelled by a few factors:
- Affordability
- Proven efficacy.
- Consumer familiarity and positive associations.
- Ease of formulation and stability.
Hyaluronic acid is typically present in cosmetic products as “sodium hyaluronate”. It is the salt form of hyaluronic acid and it has been produced in masses, making it a very affordable cosmetic ingredient. With new product development (NPD) departments constantly trying to cut costs in this economy, the addition of an affordable skincare active is an efficient way to boost the product’s status without increasing the price margin greatly.
Consumers like what they know, and with major brands already educating consumers about hyaluronic acid, consumers are more likely to purchase products with ingredients they have heard of.
Hyaluronic acid is water soluble, meaning it can be easily added to formulations with a large percentile of water. Luckily, a lot of cosmetic formulations are oil in water (o/w) creams, meaning that this ingredient is easily added to the water phase of lotions. Hyaluronic acid also doesn’t have many stability issues, unlike our retinoid friends, making them a formulator’s best friend.
New product development departments usually don’t have a huge budget for research and claims substantiation. Luckily, hyaluronic acid is a well studied and scientifically proven ingredient, so claims about the ingredient and product as whole can be made without much additional cost. (Are you starting to see the trend here?)
Is HA worth the hype?
Yes, and no. I know, I know, everyone always says there are two sides of the coin! On the one hand, hyaluronic acid is an amazing ingredient and I recommend that everyone incorporates it into their skincare routine. However, I wouldn’t go out of my way to buy a high percentage hyaluronic acid serum, it’s simply not necessary.
So many products already have this skincare active in their most basic of formulas, it would be more worthwhile (and cost effective) to buy a day or night moisturiser with hyaluronic acid and call it a day.
Do I recommend hyaluronic acid in your skincare routine?
100%
Do I think you need to go buy a hyaluronic acid serum for daily use?
No
how to incorporate HA into your skincare routine
Because HAcan be formulated in to practically any product, I recommend using a product for daily use (such as a day or night cream).
Watched out for the ingredient in the ingredients list as any of the below:
- Sodium Hyaluronate.
- Hyaluronic Acid.
- Hydrolysed Hyaluronic Acid.
- Sodium Acetylated Hyaluronate.
- Sodium Hyaluronate Crosspolymer.
Clinical Evidence
Numerous studies have validated the cosmetic efficacy of HA. A clinical trial published in the Journal of Clinical and Aesthetic Dermatology (2011) demonstrated significant improvements in skin hydration and elasticity after 8 weeks of topical HA use. Another study in the Journal of Drugs in Dermatology (2014) evaluated different molecular weights of HA and confirmed that both HMW-HA and LMW-HA improve skin hydration, though LMW-HA showed deeper skin penetration and longer-lasting effects.
A randomized, double-blind trial published in Dermatology and Therapy (2016) investigated the efficacy of HA-based creams and found measurable improvements in wrinkle depth and skin firmness over a 12-week period. These results support the utility of HA as a cornerstone ingredient in anti-aging and moisturizing products.
Regulatory Status
Hyaluronic acid has a strong history of safe use in cosmetic and medical applications. It is listed by the U.S. Food and Drug Administration (FDA) as generally recognized as safe (GRAS) and is also approved for use in dermal fillers and ophthalmic products. In the European Union, HA is permitted in cosmetic products without restriction, provided it complies with purity and quality standards.
The Cosmetic Ingredient Review (CIR) Expert Panel has concluded that HA and its salts (e.g., sodium hyaluronate) are safe for use in cosmetics. Adverse reactions are rare and typically associated with high concentrations or injectable use rather than topical application.
Formulation Considerations
Hyaluronic acid is used in a range of concentrations (typically 0.1–2%) and molecular weights to tailor its effects. HMW-HA is ideal for surface hydration and immediate skin smoothing, while LMW-HA and ultra-low molecular weight HA are used for deeper skin penetration and longer-term anti-aging benefits.
Stability is a key concern in HA formulation. HA can degrade in the presence of high temperatures or extreme pH levels, so formulators must carefully control these variables. Combining HA with stabilizers like glycerin or preservatives like phenoxyethanol helps maintain product efficacy.
Because of its hydrophilic nature, HA is often combined with occlusive agents (like dimethicone) or emollients to lock in moisture and further enhance barrier function. Encapsulation technologies, such as liposomes or nanoparticles, are also being explored to improve HA delivery and performance in the skin.
