Interestingly, hyaluronic acid has a counterpart called sodium hyaluronate. Sodium Hyaluronate is a water-soluble salt of hyaluronic acid that weighs 1000 times more than water. The ingredients in the form of salt are more stable and less prone to oxidation. Both forms are used in cosmetic products, but marketers refer to both as "hyaluronic acid," even though there are some key differences between them. Namely, sodium hyaluronate has a much smaller particle size, which allows it to better penetrate the skin. In skin care, there is a recipe for how well products penetrate the skin using molecular weight. The lower the weight, the more it can penetrate. In order for hyaluronic acid to really penetrate the skin's surface, it must undergo bioengineering treatments to achieve a much lower molecular weight. When applied topically, hyaluronic acid acts as a humectant to draw moisture into the upper layers of the skin. Unlike retinol or vitamin C, which has a different percentage, HA has a different weight. Low molecular weight HA is what you are looking for in skin care as HA with a higher molecular weight cannot penetrate the skin's protective barrier. Research clearly shows that the lower the molecular weight of the active ingredient, the greater the penetration into the skin and the greater its hydration.