N-3 and N-6 pufas in healthy and diseased skin

Western type diets do hardly provide the recommended intakes of certain long-chain polyunsaturated fatty acids (LC-PUFAs), although research revealed their functionality and essentiality that was even honored with a Nobelprize in 1982. LC-PUFAs exert 2 major biological functions: Structural elements of membranes A double layer of phospholipids, containing besides other FA also LC- PUFAs (arachidonic acid, docosahexaenoic acid), is responsible for the particular properties of membranes. They are highly selective permeability barriers that carry metabolic active proteins like the energy conversion process, gap junctions to control the flow of information between cells and receptors for external stimuli. The transdermal waterloss is mostly due to the linoleic acid content of the skin, although γ-linolenic acid might be as important as well. Messengers All LC-PUFAs containing 20 carbon atoms are precursors of eicosanoids. This includes dihomo-γ-linolenic acid (DGLA): C20:3 co-6 Arachidonic acid (AA): C20:4 ω-6 Eicosapentaenoic acid (EPA): C20:5 ω-3 Eicosanoids act as local hormones interfering with cellular regulation. In the skin, they can evoke pro-inflammatory or anti-inflammatory reactions, depending on the precursor fatty acid. A balanced application of ω-3 and ω-6 PUFAs, either by food or by supplements, may thus alleviate inflammatory skin disorders. Based on these multiple involvements in our metabolism and their importance for health, the following recommendations have been elaborated by scientific societies and authorities: During a workshop on the essentiality of to-6 and ω-3 fatty acids, April 7-9 1999, in Bethesda, a daily intake of about 0.65 g EPA plus DHA /day has been recommended. This is in good agreement with dietary guidelines, revision 2000, by the American Heart Association and with the qualified health claim issued by the FDA on October 31, 2000, and other scientific recommendations. Since this can hardly be achieved by eating fish only by a majority of the population, alternative sources have to be explored.