Ceramides are lipids (fats) that occur naturally in skin –they play an important role in protecting our skin against environmental threats and helping it look younger. They are beneficial for stressed, sensitive, scaly, rough, dry, aged, and sun-damaged skin.
The goopy stuff between our skin cells is called extracellular matrix that consists mainly of lipids. And ceramides are about 50% of those lipids (the other important ones are cholesterol with 25% and fatty acids with 15%). Ceramides play an essential role in the structure of superficial epidermal layers.
Ceramide 1, or more recently called Ceramide EOP, was the first one that was identified in 1982. It contains the essential fatty acid, linoleic acid and has a unique structure. It's believed that ceramide 1 plays a "binding role" in the lipid layers of the extracellular matrix.
When incorporated into a skincare preparation, the topical application of ceramides could benefit the stratum corneum if the ceramides manage to fill the intercellular spaces and if they are hydrolyzed by the correct extracellular enzymes on the skin.
Ceramides are most effective when combined with other ‘skin-identical’ ingredients such as amino acids, glycerin and cholesterol. These lipid mixtures are great for improving skin tone and texture and for reducing signs of irritated skin.