You may have heard about hyaluronic acid and its skin care properties. But, do you know that not all hyaluronic acid ingredients are the same or have the same characteristics. In this post, we will discover how to differentiate among hyaluronic types, in addition to choose the most convenient one to formulate.
Properties of hyaluronic acid
Hyaluronic acid is a polysaccharide that is found naturally in the skin, vitreous humour of the eyes, synovial fluid present in the joints, and in organs such as the heart and lung.
The main function of hyaluronic acid in the skin is to maintain hydration thanks to its ability to absorb water molecules. When found in the dermis, hyaluronic acid participates in the regulation of osmotic pressure and in the balance of ions and water .
Hyaluronic acid plays a fundamental role in skin aging; in aged skin we find less hyaluronic acid in the epidermis. This causes the skin’s water retention capacity to decrease and its hydration is lost. While, in the dermis, the amount of collagen and hyaluronic acid is reduced, thus decreasing the elasticity of the skin .
When a wound or blow occurs, the inflammation process begins in which the synthesis of hyaluronic acid increases rapidly. This binds to fibronectin to begin the wound healing process .
Sodium hyaluronate 0.2% is used as a main ingredient to improve acute and chronic wounds.
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Hyaluronic acid is a natural part of the content of eye tears. In addition, it has been used for more than 30 years in ophthalmology thanks to its lubricating, anti-inflammatory, and antitoxic properties on the surface of the eye.
Several clinical studies have shown that hyaluronic acid as the active ingredient in artificial tears in concentrations between 0.1% and 0.4% is a safe and effective ingredient for the treatment of dry eye .
Types of hyaluronic acid
The different types of hyaluronic acid are distinguished by their difference in molecular weight. Thus, the higher molecular weight acid (>500 kDa) protects the joints with its lubricating property and inhibits cell growth. After binding to the CD44 receptor, the production of fibronectin present in the extracellular matrix is stimulated, contributing to the elasticity of the skin [5,6].
While the lower molecular weight hyaluronic acid (350 kDa) stimulates the production of both filaggrin, a protein involved in atopic dermatitis. Filaggrin levels are related to the level of hydration of the skin by maintaining its permeability and barrier function.
Hyaluronic acid has two salt forms: sodium hyaluronate and potassium hyaluronate. The main difference is that sodium hyaluronate has a lower molecular weight, which allows it to penetrate deeper layers of the skin. Furthermore, sodium hyaluronate has greater stability and shelf life than hyaluronic acid, making it an interesting ingredient to be used in cosmetic compositions.
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Hyaluronic acid is an ingredient that is used beyond the pharmaceutical industry. It also serves as a delivery system and is used in both nutraceutical and cosmetic compositions.
The properties that make hyaluronic acid an ideal ingredient to use in various cosmetic formulations are its viscoelastic nature, its lack of immunogenicity, its high hygroscopy and biocompatibility .
In anti-aging cosmetic formulations, hyaluronic acid acts as a skin moisturizing agent and a modifier of the viscosity of the formulation. Thus, low molecular weight hyaluronic acid is used for its moisturizing and skin regeneration capacity. While high molecular weight hyaluronic acid forms a film that reduces water evaporation from the skin and therefore has an occlusive effect .
We can also find hyaluronic acid used as a release system. Products formulated for the topical treatment of actinic keratosis or inflammatory skin diseases, hyaluronic acid acts by increasing the penetration of the active ingredient through the stratum corneum.
The percentages of hyaluronic acid used in cosmetic formulations vary from 0.2 to 1%. While the maximum concentration of sodium hyaluronate found in marketed body lotions can reach 2% .
The different forms of hyaluronic acid share similar properties in skin care, so the use of one type or another will depend on the composition and properties that you want to add to the final formulation.
- Bravo, B., Correia, P., Gonçalves Junior, J. E., Sant’Anna, B., & Kerob, D. (2022). Benefits of topical hyaluronic acid for skin quality and signs of skin aging: From literature review to clinical evidence. Dermatologic therapy, 35(12), e15903. https://doi.org/10.1111/dth.15903
- Papakonstantinou, E., Roth, M., & Karakiulakis, G. (2012). Hyaluronic acid: A key molecule in skin aging. Dermato-endocrinology, 4(3), 253–258. https://doi.org/10.4161/derm.21923
- Frenkel J. S. (2014). The role of hyaluronan in wound healing. International wound journal, 11(2), 159–163. https://doi.org/10.1111/j.1742-481X.2012.01057.x
- Hynnekleiv, L., Magno, M., Vernhardsdottir, R. R., Moschowits, E., Tønseth, K. A., Dartt, D. A., Vehof, J., & Utheim, T. P. (2022). Hyaluronic acid in the treatment of dry eye disease. Acta ophthalmologica, 100(8), 844–860. https://doi.org/10.1111/aos.15159
- Antonio CR, Trídico LA. The importance of interaction between hyaluronic acid and CD44 receptor. Surg Cosmet Dermatol. 2021;13:20210006.
- Snetkov, P., Zakharova, K., Morozkina, S., Olekhnovich, R., & Uspenskaya, M. (2020). Hyaluronic Acid: The Influence of Molecular Weight on Structural, Physical, Physico-Chemical, and Degradable Properties of Biopolymer. Polymers, 12(8), 1800. https://doi.org/10.3390/polym12081800
- Juncan, A. M., Moisă, D. G., Santini, A., Morgovan, C., Rus, L. L., Vonica-Țincu, A. L., & Loghin, F. (2021). Advantages of Hyaluronic Acid and Its Combination with Other Bioactive Ingredients in Cosmeceuticals. Molecules (Basel, Switzerland), 26(15), 4429. https://doi.org/10.3390/molecules26154429
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