Ceramide is a substance that exists in intercellular lipids, a substance found between keratinocytes that protects cells, and is related to moisturizing and protection of keratinocytes. Ceramide is said to account for approximately 50% of intercellular lipids, and reduced levels of this substance leads both to lowered skin resistance facilitating the occurrence of inflammation and to moisture deficiency causing dry skin. As well as natural ceramide, synthetically produced ceramide is also available. Synthetic ceramide is similar in structure to natural ceramide and demonstrates identical effects. In addition, phytoceramide, a substance obtained from plants, is also available.