Effects of Fat and Fatty Acid Intake on Inflammatory and Immune Responses: A Critical Review

Abstract

intakes, and the relative relevance of direct AA intakes versus endogenous production, have not been fully assessed.• Formation of LC n-3 FA, especially to DHA, from ALA appears to be rather inefficient, although somewhat higher conversion rates have been shown in premenopausal women than in men [Giltay et al., 2004].• There is competition between the two metabolic pathways, especially at the desaturation steps, and at the cellular level competition may also take place for the esterification into the 2 position of glycerol of glycerolipids, depending on the relative abundance of the competing FA [Visioli et al., 2006].• Since the production of LC PUFA from precursors and of the transporters (e.g.lipoproteins) from the site of synthesis to cells takes place mainly in the liver, hepatic metabolism in relation to physiological states (e.g.neonates, pregnancy, ageing) and to pathological conditions may affect the overall availability of LC PUFA to cellular compartments.An additional relevant issue in the overall relationships between the intakes of LC PUFA, especially those that are present in very low amounts in the diet while being of unique nutritional importance, such as the LC n-3 PUFA, concerns their bioavailability in relation to the matrix (food vs. formulation).Available data indicate that elevation of circulating levels of these FA is greater when they are ingested as food components rather than as formu-