Essential fatty acids and the brain: possible health implications

Linoleic and a-linolenic acid are essential for normal cellular function, a nd act as precursors for the synthesis of longer chained polyunsaturated fa tty acids (PUFAs) such as arachidonic (AA), eicosapentaenoic (EPA) and doco sahexaenoic acids (DHA), which have been shown to partake in numerous cellu lar functions affecting membrane fluidity, membrane enzyme activities and e icosanoid synthesis. The brain is particularly rich in PUFAs such as DHA, a nd changes in tissue membrane composition of these PUFAs reflect that of th e dietary source. The decline in structural and functional integrity of thi s tissue appears to correlate with loss in membrane DHA concentrations. Ara chidonic acid, also predominant in this tissue, is a major precursor for th e synthesis of eicosanoids, that serve as intracellular or extracellular si gnals. With aging comes a likely increase in reactive oxygen species and he nce a concomitant decline in membrane PUFA concentrations, and with it, cog nitive impairment. Neurodegenerative disorders such as Parkinson's and Alzh eimer's disease also appear to exhibit membrane loss of PUFAs. Thus it may be that an optimal diet with a balance of n-6 and n-3 fatty acids may help to delay their onset or reduce the insult to brain Functions which these di seases elicit. Published by Elsevier Science Ltd.