Three updates of this review have resulted in more included studies and more people randomised but still relatively little useful additional data. The results remain inconclusive. The new trials all compare the omega-3 polyunsaturated fatty acids, in particular eicosapentaenoic acid and its ester, ethyl-eicosapentaenoic acid. The use of omega-3 polyunsaturated fatty acids for schizophrenia still remains experimental and this review highlights the need for large, well designed, conducted and reported studies.
A placebo-controlled trial of omega-3 fatty acid (ethyl eicosapentaenoic acid) supplementation for residual symptoms and cognitive impairment in schizophrenia.
This study determined if augmentation of neuroleptics with 3 g/day of ethyl eicosapentaenoic acid (EPA) improves symptoms and cognition in patients with schizophrenia or schizoaffective disorder.
                Eighty-seven patients meeting criteria for schizophrenia or schizoaffective disorder who had residual symptoms despite neuroleptic treatment were randomly assigned to receive either 3 g/day of ethyl EPA (N=43) or placebo (N=44) in a 16-week, double-blind supplementation trial. Assessments were performed at baseline and at weeks 1, 2, 4, 8, 12, and 16; a cognitive battery was administered at baseline and at week 16.
                No differences were found between groups in positive or negative symptoms, mood, cognition, or global impression ratings. Results were similar for the intention-to-treat (N=87) and completer (N=75) groups.
                For schizophrenia patients treated with 3 g/day of ethyl EPA, improvement in residual symptoms and cognitive impairment was no greater than for schizophrenia patients treated with placebo.