Lipids in the nutritional treatment of inflammatory diseases | Ruolo dei lipidi nel trattamento nutrizionale delle patologie infiammatorie

Fatty acids can be broadly divided into saturated, monounsaturated and polyunsaturated acids on the basis of the number of double bonds. Depending on the position of the first double bond, counted from the methyl end, polyunsaturated fatty acids can be further subdivided into series n-3 or n-6. Dietary fatty acids, mainly consisting of essential fatty acids linoleic acid (C18:2, n-6) and linolenic acid (C18:3, n-3), in mammalian cells can be further elongated or desaturated (with the addition of more double bonds). As the elongation and desaturation enzymes are the same for both n-6 and n-3 fatty acids, the two series compete for the same pattern of enzymes for their transformation into fatty acids with a higher number of carbon atoms and double bonds. Polyunsaturated fatty acids of the n-6 and n-3 series are used in the cells mainly as components of biological membrane phospholipids. Following an injurious stimulus starting an inflammatory process, polyunsaturated fatty acids of membrane phospholipids are released into the cell and are transformed into molecules called eicosanoids. Eicosanoids derived from fatty acids of the n-6 series have generally a proinflammation effect, while eicosanoids derived from fatty acids of the n-3 series have an anti-inflammatory and resolutive effect on the triggered inflammatory process. Taken together, these considerations suggest that the introduction of polyunsaturated fatty acids of the n-3 series in an appropriate ratio with respect to fatty acids of the n-6 series may reduce both acute and chronic effects of inflammation. Beneficial effects from the use of polyunsaturated fatty acids of the n-3 series have also been reported in allergic diseases and some forms of respiratory diseases