Positive Health Online

Abstract

BOURRE, INSERM Research Director. Unit U26 Neuro-pharmaco-nutrition. Hopital Fernand Widal, 200 rue du Faubourg Saint Denis, 75745 Paris cedex 10, France, jean-marie.bourre@fwidal.inserm.fr, has reviewed (181 references) the role of n-3 fatty acids in the brain at various life stages, particularly during ageing. Abstract: Even though the brain is materially an organ like any other, that is to say elaborated from substances present in the diet (sometimes exclusively), for long it was not accepted that food can have an influence on brain structure, and thus on its function. Lipids, and especially n-3 fatty acids, have provided the first coherent experimental demonstration of the effect of diet (nutrients) on the structure and function of the brain. Alpha-linolenic acid deficiency alters the structure and function of membranes and induces minor cerebral dysfunctions, as demonstrated in animal models and in human infants. It has been shown that alpha-linolenic acid deficiency alters the course of brain development, and perturbs the composition and physicochemical properties of brain cell membranes, neurones, and glial cells. As a consequence, the nature of polyunsaturated fatty acids present in formula milks for infants conditions the visual and cerebral abilities, including intellectual. Moreover, dietary n-3 fatty acids are involved in the prevention of cardiovascular disease, and in some neuropsychiatric disorders, particularly depression, as well as in dementia, notably Alzheimer's disease. Recent results have shown that dietary alpha-linolenic acid deficiency induces more marked abnormalities in certain cerebral structures than in others. Particularly the frontal cortex and pituitary gland are more severely affected. These selective lesions are accompanied by behavioural disorders more particularly affecting certain tests (habituation, adaptation to new situations). Alpha-linolenic acid deficiency decreases the perception of pleasure by slightly altering the efficacy of sensory organs and by affecting certain cerebral structures. Fatty acids that are essential for the brain are arachidonic acid and cervonic acid, derived from the diet, unless they are synthesized by the liver from linoleic acid and alpha-linolenic acid. The age-related reduction of hepatic desaturase activities (an enzyme which participate in the synthesis of long chains) can impair turnover of cerebral membranes. In many structures, especially in the frontal cortex, a reduction of cervonic and arachidonic acids is observed during ageing. Peroxisomal oxidation of polyunsaturated fatty acids decreases in the brain during ageing, participating in decreased turnover of membrane fatty acids, which are also less effectively protected against peroxidation by free radicals.

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References

Bourre J M. Roles of unsaturated fatty acids (especially omega-3 fatty acids) in the brain at various ages and during ageing. Journal of Nutrition, Health & Aging. 8(3): 163-74, 2004.