Sodium PCA is the sodium salt of PCA (pyrrolidone carboxylic acid, a natural amino acid derivative). Sodium PCA occurs in the skin is part of the skin's natural moisturizing factor (NMF). As such, it can also be found in both plant and animal tissues.
Its value comes from its function as a humectant, meaning it helps the skin's top layer both draw in and retain moisture, resulting in a more supple, youthful appearance. Because of these properties, it is a staple in many moisturizers, providing moisture without being thick or occlusive.
It is considered safe and non-irritating as used in skin care products, where concentrations typically range from 0.2-4%. It is sensitive to both light and heat, which means that products containing it must be packed in opaque and air-tight containers. https://www.paulaschoice.com/ingredient-dictionary/ingredient-sodium-pca.html?q=Sodium%20PCA&fdid=ingredients