Membrane composition and cellular responses to fatty acid intakes and factors explaining the variation in response

The lipid membrane bilayer undergoes continuous changes, and its lipid composition is both adaptive and highly varied, with substantial molecular variety. The balance of dietary fats, namely saturated versus unsaturated, and polyunsaturated fatty acids (PUFA) of the n-6 series versus those of the n-3 series, may change membrane composition thus affecting membrane order, intracellular signaling processes, and gene expression. As a consequence, changes in the production of both lipid and peptide mediators influencing the individual adaptive responses take place. More than that of all the other fatty acids, the n-3 PUFA composition of cell membranes depends on their dietary intake. n-3 PUFA levels in cell membranes are related to both inflammatory and immune diseases, possibly by downregulating the expression of genes involved in their synthesis and maybe the pathogenesis of processes associated with the disease itself. The interindividual variability of DNA sequences involved in the synthesis of long-chain PUFA may explain differences in responses to their dietary contribution in regulating the risk of disease. Lifestyle factors (such as smoking and alcohol consumption) may in turn negatively impact PUFA metabolism. Accordingly, different amounts of dietary PUFA may be necessary to meet the requirements for these nutrients in development and disease prevention on an individual basis.