The essential n-3 fatty acid α-linolenic acid (C18:3) serves as an energy carrier and precursor for the synthesis of EPA (C20:5) and DHA (C22:6) into which it is converted by chain elongation and introduction of extra double bonds. EPA is an important component of the phospholipids of cell membranes and lipoproteins. DHA is a structural component in the cell membranes, particularly the nervous tissue of the brain, and plays an important role both for the synapses and the cells of the retina.