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.
Randomized, placebo-controlled study of ethyl-eicosapentaenoic acid as supplemental treatment in schizophrenia.
The study investigated the efficacy and tolerability of ethyl-eicosapentaenoic acid (E-EPA) as add-on treatment in chronic, severe schizophrenia.
                A randomized, parallel-group, double-blind, placebo-controlled, fixed-dose, add-on study was conducted over 12 weeks. Forty patients with persistent symptoms after at least 6 months of stable antipsychotic treatment received E-EPA or placebo, in addition to their existing treatment.
                At 12 weeks, the E-EPA group had significantly greater reduction of Positive and Negative Syndrome Scale total scores and of dyskinesia scores than the placebo group.
                EPA may be an effective and well-tolerated add-on treatment in schizophrenia.