Omega-3 has been shown in numerous studies to have a beneficial effect on mental health and particularly on mood. In a direct comparison with Prozac, 1g EPA was as effective as the drug in reducing depressive symptoms(1).Many patients are reluctant to take psychotrophic drugs, so the option of an effective natural alternative with virtually no side effects is good news indeed. There have been several studies showing an improvement in mood with Omega-3 particularly EPA(2,3) In one study the ratio of Omega-6 to Omega-3 was studied and showed the lower the ratio the better the response(4). Omega-3 has also been shown to improve anxiety symptoms in a placebo controlled trial(5). High levels of Omega-3 reduce the risk of post natal depression, those with lower levels of Omega-3 being more likely to require antidepressants in the first year after giving birth(6). Countries with a high level of Omega-3 in their diet, such as Japan, have the lowest levels of depression and suicide(7). Interestingly this association also holds true for murder as well as suicide(8). From these and other clinical studies it appears that a healthy brain needs to have an optimal amount of Omega-3. Omega-6 intakes have been linked with violent behaviour whereas Omega-3 combined with a vitamin and mineral supplement was shown to reduce aggressive behaviour among prisoners(9). Omega-3 has also been shown to be helpful in more serious mental health conditions such as bipolar disorder(10) and schizophrenia(11).

References

(1). Jazayeri S, Tehrani-Doost M, Keshavarz SA, Hosseini M, Djazayery A, Amini H, Jalali M, Peet M Comparison of therapeutic effects of omega-3 fatty acid eicosapentaenoic acid and fluoxetine, separately and in combination, in major depressive disorder. Aust N Z J Psychiatry. 2008Mar;42(3):192-8.
(2). Catherine Feart, E. Peuchant, L. Letenneur, C. Samieri, D. Montagnier, A. Fourrier-Reglat, P. Barberger-Gateau “Plasma eicosapentaenoic acid is inversely associated with severity of depressive symptomatology in the elderly: data from the Bordeaux sample of the Three-City Study” American Journal of Clinical NutritionMay 2008, Volume 87, Number 5, Pages 1156-1162.
(3).Carney et al.Omega-3Augmentation of Sertraline in Treatment of Depression in Patients with Coronary Heart Disease:A Randomized Controlled Trial. JAMA The Journal of the American Medical Association, 2009.
(4). Peter Adams, Sheryl Lawson, Andrew Sanigorski, Andrew Sinclair Arachidonic acid to eicosapentaenoic acid ratio in blood correlates positively with clinical symptoms of depression Export Lipids, Vol. 31, No. 1. (1 March 1996), pp. S157-S161.
(5). Buydens-Branchey L, Branchey M. n-3 polyunsaturated fatty acids decrease anxiety feelings in a population of substance abusers. JClin Psychopharmacol. 2006;26(6):661-5.
(6). StrømM,Mortensen EL,Halldorsson TI, et al. Fish and long-chain n-3 polyunsaturated fatty acid intakes during pregnancy and risk of postpartum depression: a prospective study based on a large national birth cohort. Am J Clin Nutr. 2009;90(1):149-5.
(7). Hibbeln JR. Fish consumption and major depression. Lancet. 1998;351:1213.
(8). Hibbeln JR, Nieminen, LRG, LandsWEM Increasing homicide rates and linoleic acid consumption among fivewestern countries, 1961-2000. Lipids 2004; 23: 1207-1213.
(9).Gesch et al 2002. Influence of supplementary vitamins, minerals and essential fatty acids on the antisocial behaviour of young adult prisoners. Randomised, placebo-controlled trial.
(10). Stoll AL, Locke CA,Marangell LB, et al. Omega-3 fatty acids and bipolar disorder: a review. Prostaglandins Leukot Essent FattyAcids. 1999;60(5-6):329-37.
(11). PeetM,HorrobinD(2002).Adose-ranging exploratory study of the effects of ethyl-eicosapentaenoate in patients with persistent schizophrenic symptoms. Journal of Psychiatric Research, 36 7-18.