Squalene

Squalene is a type of natural oily liquid originally derived from shark liver, although it has since been found in olive, peanut, and pumpkin oils, among other plant oils, in small proportions. In human skin, squalene is one of the major components of sebum, about 13%, which plays a very important part in maintaining the moisture barrier and general hydration of the skin. But squalene, being skin-identical, does restore skin's natural oils, acting also as an NMF that contributes to maintaining the skin in its soft and smooth state.

Squalene is chemically an unsaturated hydrocarbon-that is, its molecular structure includes double bonds. These double bonds serve to provide its antioxidant activity by scavenging free radicals and protecting skin surfaces from oxidative stress. On the other hand, these double bonds also make squalene prone to oxidation, which may degrade this material with time, thus decreasing its shelf life in cosmetic formulations.

To circumvent the instability issues of squalene, the cosmetic industry uses its hydrogenated, fully saturated counterpart, a substance known as squalane. Because the squalane molecule does not contain double bonds, unlike squalene, it is significantly more stable and less prone to oxidation. The increased stability of squalane makes this an ideal active for cosmetic formulation, since it imparts similar skin-conditioning and moisturizing properties to squalene but has longer shelf lives. Lightweight and non-greasy, it is quickly absorbed into the skin, hence its popular use in everything from moisturizers to serums.

In addition to that, squalene and squalane are known for skin elasticity, reduction of fine lines and wrinkles, and protection against environmental damage. Squalane itself is easily tolerated by most skin types, even sensitive or blemished ones, which positions it as one of the most versatile and useful ingredients in modern skincare.