background More and more interest is being shown in fish oil because it contains omega-3 fatty acids which may have beneficial effects in a wide range of somatic and psychiatric disorders.
aim To search the literature for evidence of the effectiveness of omega-3 fatty acids in affective disorders.
method We studied the literature with the help of Pubmed (1966-March 2006) using the keywords 'depression', 'affective disorder', 'bipolar disorder', 'seasonal affective disorder', 'postpartum depression', 'puerperal depression', 'fatty acids', 'eicosapentaenoic acid', 'arachidonic acid', 'docosahexaenoic acid' and 'fish oil'. We obtained additional information from the bibliographic references attached to the articles concerned.
results Epidemiological studies and studies on fatty acid concentrations suggest a link between omega-3 fatty acids and affective disorders, although some of the results are contradictory. Some clinical investigations found that treatment with omega-3 fatty acids did have a positive effect, but the number of test subjects was very limited and some investigations even produced negative results.
conclusion There is insufficient clinical evidence to prove conclusively that treatment with omega-3 fatty acids has a beneficial effect on affective disorders.