Linoleic acid is an 18 carbon, omega-6 fatty acid that is abundant in many plant oils. It is an essential fatty acid in animals and is the precursor in the synthesis of arachidonic acid and other polyunsaturated fatty acids. The conjugated linoleic acids cis-9, trans-11 and trans-10, cis-12 inhibit linoleic acid elongation to eicosadienoic acid.{50577} Linoleic acid supplements have been used to try to help prevent cystic fibrosis, dermatitis, and diabetes but the precise mechanisms have proven elusive. It is commonly used in dermatological cosmetics, soaps, and emulsifiers. In some fungus linoleic acid is converted to oxylipins, important compounds of the fungal life cycle{50578}, and it may play a direct role in the epidermal permeability barrier.{50579}