Brain and Essential Fatty Acids
It is now well established that 60 percent of the non-water content of the human brain is fat. About 20 percent of the brain’s dry mass is made of four unsaturated fatty acids – EPA and DHA from the omega-3 series, and DGLA and AA from the omega-6 series. These fats have unique biological properties due to partly the number of double bonds in their long carbon chains. On the other hand, saturated fats have no such double bonds while monosaturated fats such as oleic acid, found in olive oil, have just one double bond.
AA and DHA are main constituents of neuronal membranes. AA and DHA make up 15-20 percent of brain’s dry mass and more than 30 percent of the retina. During prenatal development, adequate supply of highly unsaturated fatty acids (HUFA) is essential. Studies have shown that the placenta doubles the levels of highly unsaturated fatty acids in maternal plasma to meet the needs of the growing fetal brain.
Brain gray matter continues to expand till the age of 12. Adding DHA to diets of children under 12 may be a way to replenish this fatty acid in their brains, influencing cognitive function.
DHA is particularly concentrated in highly active sites such as synapses and photoreceptors. It is essential for normal visual and cognitive development. In early life, highly unsaturated fatty acids are essential in supporting further brain growth and maturation and are therefore found in breast milk. Studies comparing the effects of infant formula with and without pre-formed highly unsaturated fatty acids have shown clear advantages of adding highly unsaturated fatty acids for both visual and cognitive development of infants.
Highly unsaturated fatty acids are essential for maintaining the fluidity or elasticity of neuronal membranes. This fluidity is key for the proper functioning of the membrane-bound and membrane-associated proteins that carry the chemical or electrical signals underlying all information processing in the brain. Certain highly unsaturated fatty acids – notably AA and EPA - also play key roles as ‘second messengers’ in chemical neurotransmitter systems, as well as contributing to many other aspects of cell signaling.
Fatty Acid Deficiency and Brain Disorders: From Fetus to Infancy to Aging
As essential fatty acids must be obtained from the diet, their deficiency is bound to disrupt major physiological activities. The worst affected organ because of their deficiency is brain. Brain needs a continuous supply of fatty acids throughout life. But the most critical stages when fatty acids are needed are infancy and aging. During infancy, essential fatty acids deficiency delays brain development. During aging, such deficiency speeds up the degeneration of brain cells.