Ceramides can be found in the stratum corneum which has the important function of protecting the skin from the elements, pollutants, and from microbial assault. The stratum corneum also ensures that elements such as nutrients and water get in and out of the skin.
The stratum corneum has a unique structure in that it is arranged in a ‘brick and mortar’ wall-type structure called the lamellar bilayer – the corneocytes resemble flattened bricks which are embedded in the lipid-enriched mortar. This mortar is water-repellent and consists of a blend of ceramides, saturated fatty acids and cholesterol which act as gatekeeper by restricting the outward flow of water and electrolytes, as well as controlling the inward absorption of chemical substances, allergens and microbial pathogens. The sebum, which is produced by the sebaceous glands forms a film over the top of the skin to provide additional protection.
The word ceramide comes from the Latin cera (wax) and amide. Structurally, they are sphingolipids where fatty acid is connected to sphingosine via amide linkage. Sphingosines constitute a class of natural products containing a long aliphatic chain with a polar 2-amino-1,3-diol terminus. Sphingosines can be found in all animal cell membranes as well as many plant cell membranes and play an important role in various complex biological processes such as cellular recognition, growth, and development.
Newborn babies are born with a protective layer called the Vernix caseasa, which, like the mortar in the stratum corneum of matured skin, consists of cholesterol, free fatty acids, ceramides and water. Since the skin barrier function in neonatal skin is still immature, the vernix layer increases hydration, plasticity and the suppleness of the stratum corneum. It also inhibits the growth of harmful bacteria, decreases skin surface pH to slightly acidic, forming an acid mantle to defend the skin against infection and to optimize the composition of the skin flora. This acidification is important for the skin barrier to develop to the fullest and to activate the enzymes that are involved in the maturation of the skin. It normally takes a year for the skin barrier to develop.
In mature skin, stress, sunlight exposure, surfactants, alcohol-based sanitisers, low humidity conditions and ageing reduce ceramide levels, which in turn result in a decrease in skin barrier function and the water binding capacity of the stratum corneum. The end result is dry skin, or ashiness as it present itself on darker skin!
Epidermal lipids are vital to healthy looking skin. Low levels of skin ceramides may result in the manifestation of skin disorders associated with barrier defects, including acne, atopic dermatitis, photosensitivity, rosacea, UV damage, and xeroderma. There are studies that show the topical applications of phytospingosines, cerebrosides and ceramides to compromised skin will facilitate its repair, restoring the skin’s normal moisture barrier function.
Oat Cosmetics, which we represent, offers AvenaPLex (Avena sativa (Oat) kernel extract) which contains 4% ceramides and has been shown to upregulate hyaluronic acid synthesis in the skin when topically applied. Seiwa Kasei, another valued supplier of ours, offers Amitose 3LGA (3-Laurylglyceryl ascorbate) which is a vitamin C derivative and, among other benefits, has been shown to activate ceramide synthesis in the stratum corneum. For more information, contact our office.