Ceramides are a type of lipid found in the cell membrane of cells. Skin cells in the outermost layer of the skin called the epidermis are a rich source of ceramides. Along with other lipids like cholesterol, fatty acids, squalene and cholesterol esters, ceramides prevent loss of water through the skin that could lead to dryness. They also act as a barrier against bacteria and environmental pollutants. Ceramides, fatty acids and cholesterol work together in the outermost layer of the epidermis called the stratum corneum to prevent moisture loss and keep skin moist and supple. Ceramides make up about 40% of the lipids in the stratum corneum. There are nine different ceramides labeled 1 through 9.
Unfortunately, ceramide levels decline with age. That's one reason skin becomes drier as a person grows older. Harsh cleansers can disrupt ceramides and lipids, leading to dry skin, and some medications like cholesterol-lowering drugs alter ceramide and lipid levels in the outer layer of the epidermis. Diet plays a role too. Eating a diet that lacks essential fatty acids can disrupt skin's natural barrier against moisture loss. A certain amount of dietary fat is important for healthy skin. Not surprisingly, people on very low fat diets often have dry, flaky skin due to loss of ceramides and other lipids that help skin retain water.
Obviously, ceramides and other lipids are important for locking in moisture and preventing dry skin. That's why some makers of skin care products and cosmetics add ceramides to their skin care products as a way to replenish ceramides lost due to aging and disruption of skin's lipid barrier. To increase the ability of these ceramides to penetrate, they're sometimes combined with penetration enhancers. They may also be incorporated into liposomes, special vesicles that enhance skin penetration. These liposomes are often made of milk fats that also help to nourish skin.
Ceramides may be useful for treating some skin conditions including eczema and psoriasis. People who have eczema have fewer ceramides in the outer layer of their skin compared to people with normal skin. People with psoriasis also have deficiencies of some ceramides among the nine that have been described. Therefore, using products that contain ceramides may improve these conditions. Ceramides, cholesterol and fatty acids all play a role in maintaining skin's ability to retain moisture. That's why it's important to replenish cholesterol and fatty acids along with ceramides and to use appropriate amounts of each to maintain a ratio that resembles skin's natural, lipid barrier. Effective products contain proper ratios of these lipids.
Skin care products that contain the right ratio of ceramides, fatty acids and cholesterol are effective for rebuilding skin's natural barrier against moisture loss and beneficial for treating some skin conditions, especially eczema. For best results, most dermatologists recommend using a mild liquid cleanser that's non-irritating and non-drying along with a moisturizer that contains ceramides and other essential lipids to rebuild skin's protective barrier. There are cleansers available with ceramides that cleanse skin gently while replacing lost lipids. They're an excellent choice for people with dry or aging skin and those with eczema or psoriasis.
The benefits of ceramides in the skin go beyond keeping skin moist and supple, natural ceramides also act as signaling molecules, telling cells when to die. This could make them useful for treating cancer by causing cancer cells to self-destruct. You can find ceramides in products like skin moisturizers, eye creams, facial cleansers, sunscreens, lip gloss, lipsticks and foundations. Ceramides are also added to some hair care products and conditioners because they bind to the hair shaft and make it less porous.
Are ceramides in cosmetic products safe? The Environmental Working Group Skin Deep Cosmetics Database classifies ceramides as low hazard cosmetic ingredients. They are usually non-irritating to skin and actually soothe irritation and itching caused by dry skin.
All in all, products that contain ceramides are beneficial for people with dry skin, eczema and psoriasis. Plus, they're safe to use and don't normally cause skin irritation.