Sodium hyaluronate is the water-soluble sodium salt form of hyaluronic acid, a natural substance found in various connective tissues of humans that has a unique capacity for retaining water. Skin care products that contain sodium hyaluronate are able to efficiently hydrate the skin while giving you a smoother, younger-looking complexion.
The functions of sodium hyaluronate are based on the ability of this molecule to absorb and hold water. In fact, sodium hyaluronate is able to hold more water than any other natural substance—up to 1,000 times its weight in water! This is possible because sodium hyaluronate is a glycosaminoglycan (GAG), a long polysaccharide (sugar molecule) composed of disaccharides called amino sugars and uronic acid. GAGs are negatively charged and thus tend to attract positively charged sodium and potassium ions. In turn, this causes the GAGs to absorb and hold a large amount of water.
In the human body, sodium hyaluronate functions as a tissue lubricant and can be found wherever moisture is stored or lubrication between layers of tissue is required to eliminate friction. Examples are the vitreous body of the eye itself, the joint cartilage, the synovial fluid in the joints, all the mucus membranes of the body, and the extracellular matrix of the skin. In fact, the sodium hyaluronate found within skin account for up to 50% of the body’s total store of sodium hyaluronate.
How sodium hyaluronate benefits the skin
Did you know that youthful skin retains its turgor, resilience, and flexibility due to its high content of water? As the skin loses moisture due to both internal and external factors, it begins to show signs of aging, such as lines, wrinkles, sagging, and flaking skin. Since sodium hyaluronate is the key molecule involved with skin moisture, it’s clear that a strong relationship exists between skin aging and levels of sodium hyaluronate. According to the scholarly journal DermatoEndocrinology, the most dramatic histochemical change observed in aging skin is the marked disappearance of sodium hyaluronate in the epidermis (the top layer of skin). It is unknown why this occurs.
Sodium hyaluronate has been proven to possess a protective effect on collagen synthesis. Additionally, sodium hyaluronate can help naturally reduce signs of aging by decreasing epidermal water loss associated with sun exposure, low humidity, and other external factors associated with skin dryness.
With this understanding, scientists have figured out a way to obtain and synthesize sodium hyaluronate to use in skin care products and also in dermal injections. Sodium hyaluronate can be derived from natural plant sources and also synthetically by wheat fermentation. In the case of fermentation, wheat is fermented with specific bacteria, then purified and precipitated. This process extracts the sodium hyaluronate naturally present in the wheat.
Applying skin care products with sodium hyaluronate will help to attract moisture to the skin, resulting in smoother, softer skin with decreased wrinkles and a more plump appearance. In addition to topical products, sodium hyaluronate is also injected to reduce wrinkles on the face. As of 2017, the FDA had approved 13 hyaluronate preparations that are known as dermal fillers. They are also used as a filler of lips or in other parts of the body, though not FDA approved. The filling effect is temporary and lasts for about six months or longer in most people.
Sodium hyaluronate vs hyaluronic acid
You may be wondering why sodium hyaluronate would be used instead of hyaluronic acid when formulating a skin care product. Well, it turns out that while these two molecules are almost identical, sodium hyaluronate has a few advantages over hyaluronic acid. For instance, sodium hyaluronate has a greater chemical stability than hyaluronic acid. Additionally, sodium hyaluronate has a smaller molecular size, which means it penetrates the skin better than hyaluronic acid, and has the ability to reach the deep dermal layer of skin. It is an effective humectant type moisturizer, drawing in moisture from the environment and helping the skin retain it.
A 2009 safety report published in the International Journal of Toxicology concludes that hyaluronic acid and its sodium and potassium salts are considered safe for use in cosmetics as skin conditioning agents at concentrations up to 2%.
References: TRB Chemedica UK, “What is Sodium Hyaluronate and How Does It Work?”, Dermatoendocrinol. 2012 Jul 1; 4(3): 253–258, Drug Des Devel Ther. 2014; 8: 1923–1928, Vichy Laboratories, “Where Does Hyaluronic Acid Come From?”, Wikipedia, “Sodium Hyaluronate”, Lesliebaumann.com “Hyaluronic Acid”, Int J Toxicol. 2009 Jul-Aug;28(4 Suppl):5-67