M. HASAN MOHAJERI, ROBERT J. WINWOOD*

*Corresponding author

DSM Nutritional Products Ltd, Delves Road, Heanor,Derbyshire, DE75 7SG, United Kingdom

Abstract

In humans, n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) and long chain n-6 polyunsaturated fatty acid, play a crucial role in brain development and function. Docosahexaenoic acid (DHA), a n-3, is one of the major structural components of the brain. Low levels of DHA may be associated with poorer developmental outcomes and neurological disorders. Arachidonic acid (AA) is the n-6 acid that is also a major structural fatty acid in the brain. This review will concentrate on the n-3 acid DHA. The human brain undergoes rapid growth spurts, especially in the last trimester of pregnancy and throughout the first 2 years of life. During the rapid growth period, large amounts of DHA are required by the foetus and are obtained prenatally from maternal stores via placental transfer. Indeed, the placenta preferentially concentrates DHA for the foetus in a process known as biomagnification. After birth, the baby is provided DHA by breast milk or DHA enriched infant formula or food. Several lines of research show that DHA is critical to optimal cognitive development and maintenance of brain functions during pregnancy, early childhood, adolescence and adult life. Here, we briefly review some human studies describing the role of n-3 LC-PUFAs, especially DHA, in cognitive development and in the cognitive performance of infants and adolescents.

INTRODUCTION

LC-PUFAs are indispensable for cognitive development
A large body of literature documents the crucial role of nutrition in brain development, and consequently on brain function and the mental performance in humans. The mammalian central nervous system has a high lipid content (~60 percent) and the proper functioning of the brain is dependent on maintaining its specific lipid composition (1). Docosahexaenoic acid (DHA; a n-3 fatty acid) and arachidonic acid (AA, a n-6 fatty acid) are the major long-chain poly-unsaturated fatty acids (LC-PUFA) in the brain (2, 3). As the body is not able to synthesise DHA in adequate amounts, it is a conditionally essential nutrient and must be supplied by the diet (2, 4-7). Fatty acids are structurally important for biological functioning of the cell membranes due to their role in maintaining an optimal fluidity and thickness of neuronal membranes in the brain, which in turn facilitates neuronal communication (8), DHA is particularly important for brain function, as its unique structure ensures the lipid bilayer is both viscoelastic and constantly flexes (8). The “Western†...