EFAs and skin barrier function – what role do they play?
Essential fatty acids (EFAs) are those that cannot be made in the body and must be supplied externally, in the diet or as a supplement. Just what role do essential fatty acids play in the skin?
EFAs have multiple roles in the body – it’s been discovered that they are needed for neurological and ophthalmological development, as well as being important metabolically. When it comes to skin, they influence health in a number of different ways.
Cell membrane components
EFAs are incorporated into cell membranes and therefore help control the movement of molecules into and out of the cell. The individual make up of the polyunsaturated fatty acids in the membrane is highly dependent on dietary intake.
Control water loss
The top layer of skin – the stratum corneum – forms a tight barrier against loss of water and other molecules in the body and entry of irritants and other foreign material. In addition to the structural integrity of the barrier, there is an outer lipid layer of hydroxyceramide bound to the outer protein layer that forms an additional layer of protection. Increased trans-epidermal water loss can alter barrier function and leaves the skin more vulnerable to the entry of irritants.
Precursor of eicosanoids
Through the arachidonic acid cascade, essential fatty acids can result in the production of metabolically active eicosanoids such as prostaglandins and leukotrienes, which have effects on blood clotting, vasodilation/constriction, inflammation and immunity. By altering the balance between omega 6 and omega 3 EFAs, it may be possible to modulate these responses.
Hair coat quality
Various studies have shown hair gloss and softness increases when higher EFA diets are fed. This may be as a result of increased cholesteryl ester deposited on the hair shaft surface. The hair coat plays an important role not just in thermoregulation but also physically excluding irritants from the skin surface. It may also be important in limiting trans-epidermal water loss by reducing evaporation from the surface of the skin.
The layers of epidermis have a rapid turnover and essential fatty acids supplied in the diet are required constantly. Linoleic acid is especially important to maintain barrier function and prevent excessive trans-epidermal water loss. Arachidonic acid is especially important for the regulation of epidermal proliferation. The balance of omega 3 and 6 fatty acids is important for the homeostasis of a number of functions and may not always be optimally balanced in a pet’s usual diet. EFAs are especially vulnerable to destruction during heat processing and oxidation during storage.