Sodium Hyaluronate
TL;DR
Sodium Hyaluronate works as a warrior against the visible signs of aging by keeping water on top of your skin. A long sugar chain capable of forming breathable, water-rich films, Sodium Hyaluronate both slows the evaporation of water from your skin's barrier and make stores of hydration available, should your skin prove thirsty. You can think of Sodium Hyaluronate as breathable, time-release moisture.
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In formulating Geologie products, we rejected trends in favor of function. When it came to selecting an ingredient that could provide superior skin feel and moisturization properties, we choose Sodium Hyaluronate, the sodium salt version of the more popular Hyaluronic Acid. Here’s why.
Hyaluronic Acid is already present in your skin, a key glycosaminoglycan (a large type of polysaccharide, or sugar) naturally found in the water-soluble matrix between healthy skin cells. Already common to the skin microbiome, it makes sense that the skincare industry looks to Hyaluronic Acid’s utility as a moisturizer. In Geologie formulas, we used a derivative of Hyaluronic Acid that’s just as effective, yet more compatible to the surrounding formula. But before we get into our choice of Sodium Hyaluronate, let’s dive a bit deeper into what Hyaluronate is, and what it means for your skin.
What is Hyaluronate?
Hyaluronate is a long chain of repeating disaccharide (sugar) units, more generally known as a glycosaminoglycan. Each sugar unit has 4-5 spots perfect for attracting water through hydrogen bonding. When you wet Hyaluronate, each sugar unit can attract at least 20 water molecules, often more, without compromising the stable sugar structure. Those water molecules add up very quickly, prompting many to claim that Hyaluronate can hold way more than its weight in water.
Hyluronate’s ability to attract water is of no debate. It’s ability to bring water into the skin, however, is dependent on a few factors.
Hyaluronate’s ability to either absorb into the skin, bringing the water along with it, or hold water at the surface of the skin is largely dependent upon the chain’s length, more commonly expressed in terms of the chain’s total molecular weight (MW). Skin permutation may also depend on the chain’s tertiary structure (three-dimensional geometry), but we can safely ignore that consideration for these purposes.
A German study found that the longest chain that can be absorbed into the skin is 5 kDa in MW. Most cosmetic-grade Hyaluronate is well above that MW, usually by 10x as much. So instead of permeating into the skin where it would supplement the glycosaminoglycans naturally found in the extracellular matrix, these large MW Hyaluronates chains simply sit on top of the skin. When retained at the skin’s surface, Hyaluronate chains slow the evaporation of water from the skin’s surface, thus keeping the skin moisturized.
What does Hyaluronate really do for the skin?
Skincare brands are correct when they claim that Hyluronate may hold more than its weight in water. However, most marketers misspeak when they sell with (implied) claims that the Hyaluronate in their products will absorb into the skin, providing moisture from "inside out." Most brands likely do not know the average MW of their Hyaluronate chains, let alone have clinical proof that these chains actually get into the skin. If the Hyaluronate is an effective moisturizer in their products, it’s likely because the Hyaluronate is allowed to sit on the surface of the skin, and not to sink into it.
Additionally, even if the Hyaluronate chains are of appropriate length for skin permutation and subsequent “inside out” hydration, there is some evidence that Hyaluronate may work efficiently only on skin already amply hydrated. In some cases, Sodium Hyaluronate has been shown to actually restrict the delivery of water and other key macromolecules into the skin’s surface in skin’s whose barrier is compromised. Read: Hyaluronate works most effectively as a moisturizer on skin already sufficiently hydrated.
So why use Sodium Hyaluronate?
We used Sodium Hyaluronate knowing these attributes, not hoping for its touted performance. Knowing the Hyaluronate will likely sit on the skin’s surface, we decided to use a form of Hyaluronate most compatible with the rest of the formulas in which it is included. Consistent with the other Sodium salt ingredients (Sodium Benzoate, Chloride, Hydroxide, Olefin Sulfonate, and Stearoyl Lactylate), Sodium Hyaluronate helps trap water in and on the skin’s surface when the Vital Morning Face Cream is used immediately after the Everyday Face Wash. A powerful skin protectant, Sodium Hyaluronate helps keep your skin hydrated all day.
