The benefits of fish oil have been attributed to two fatty acids that are abbreviated as EPA and DHA. These play many important roles in the body: they contribute to the structural integrity of cell membranes and are converted to substances called eicosanoids that act as hormones, promoting normal communication between cells (including brain cells) and controlling inflammation. When early research showed lower rates of depression and mental illness in people who ate more fish, scientists studied the human brain and found it contains significant amounts of DHA. They concluded that DHA is best for the brain and EPA plays other roles in inflammation and heart health.
However, research failed to confirm this view. When the effects of EPA and DHA were compared in double-blind studies, EPA provided clear benefits whereas DHA did no better or marginally worse than placebo. This was seen in a number of conditions including schizophrenia and bipolar disorder (1). In a study of depressed patients who did not respond to standard medical care, pure EPA at a dose of 1 gram per day was found to be an effective treatment (2). The same dose of EPA was also found to provide some degree of help in borderline personality disorder, a condition that is usually non-responsive to drug therapy (3).
Leading fish oil researchers now believe that DHA only plays a structural role in the brain, whereas EPA contributes to its function (4). There is a critical need for DHA during fetal development and early infancy – the fact that DHA is found in breast milk is clear evidence of this. Past this early period, the need for DHA is limited and too much of it seems to actually have an adverse effect on moods.
Until recently, pure pharmaceutical-grade EPA was only available for research purposes, and all the fish oil on the market contained varying concentrations of both EPA and DHA. Now, the innovative Canadian supplement manufacturer Advanced Orthomolecular Research (AOR; see www.AOR.ca for more information) has introduced a pure EPA supplement called EPA Brite that is also available here in the online store.
(1) Schizophr Res 2001 Apr 30; 49 (3): 243-51, Prostaglandins Leukot Essent Fatty Acids, 2003 Dec; 69 (6): 477-85, Prostaglandins Leukot Essent Fatty Acids, 1999 May-Jun; 60 (5-6): 329-37
(2) Arch Gen Psychiatry, 2002 Oct; 59 (10): 913-9
(3) Am J Psychiatry, 2003 Jan; 160 (1): 167-9
(4) See The Omega 3 Connection, by Andrew Stoll, MD