Docosahexaenoic Acid and Membrane Lipid Domains

Docosahexaenoic acid (DHA, 22 6Delta4,7,10,13,16,19) is the longest chain and most unsaturated fatty acid commonly found in biological systems (1). It represents the extreme example of the important class of fatty acids known as omega-3s. Primarily through dietary studies, this fatty acid has been linked to an enormous variety of human afflictions including cancer (2, 3), heart disease (4), rheumatoid arthritis (5), lupus (6), alcoholism (7), blindness (8), respiratory diseases (9), peroxisomal disorders (10), cystic fibrosis (11), schizophrenia (12), depression (13), malaria (14), multiple sclerosis (15) and even migrane headaches. In order for one simple molecule to affect so many seemingly unrelated processes it must function at a fundamental level, common to most cells. It has been suggested that this level is in controlling membrane structure and function (16). Due to its extreme chain length and unsaturation it should be easier to demonstrate a unique role for DHA in membrane structure/function than it will be for other shorter, less unsaturated fatty acids commonly found in membranes. Reviewed here is the possible involvement of DHA in membrane lipid domains.