Authors' objectives:

The purpose of this study was to conduct a systematic review of the scientific-medical literature to identify, appraise and synthesize the evidence for the effects of omega-3 fatty acids in mental health. Evidence was sought to permit the investigation of three basic questions: the efficacy and safety of omega-3 fatty acids as (primary or supplemental) treatment of psychiatric disorders or conditions (e.g., symptoms alone); the association between intake of omega-3 fatty acids and the onset, continuation or recurrence of psychiatric disorders or conditions; and, the association between the fatty acid content of biomarkers and the onset, continuation or recurrence of psychiatric disorders or conditions. The latter two questions examined the protective value of omega-3 fatty acid content in the diet and/or blood lipid biomarkers. The impact of effect modifiers was examined as well. The results will be used largely to inform a research agenda.

Authors' results and conclusions: A notable safety profile for any type or dose of omega-3 fatty acid supplementation was not observed. Overall, other than for the topics of schizophrenia and depression, few studies were identified. Only with respect to the supplemental treatment of schizophrenia is the evidence even somewhat suggestive of omega-3 fatty acids' potential as short-term intervention. However, these meta-analytic results exclusively pertaining to 2 g/d eicosapentaenoic acid (EPA) require replication using design and methods refinements. Additional research might reveal the short-term or longterm therapeutic value of omega-3 fatty acids. One study demonstrating a significant placebo-controlled clinical effect related to 1 g/d E-EPA given, over 12 weeks, to 17 patients with depressive symptoms-rather than depressive disorders-cannot be taken to support the view of the utility of this exposure as a supplemental treatment for depressive symptomatology or disorders.

Authors' recommendations: Nothing can yet be concluded concerning the clinical utility of omega-3 fatty acids as supplemental treatment for any other psychiatric disorder or condition, or as a primary treatment for all psychiatric disorders or conditions, examined in our review. Primary treatment studies were rare. Much more research, implementing design and methods improvements, is needed before we can begin to ascertain the possible utility of (foods or supplements containing) omega-3 fatty acids as primary prevention for psychiatric disorders or conditions. Overall, almost nothing is known about the therapeutic or preventive potential of each source, type, dose or combination of omega-3 fatty acids. Studies of their primary protective potential in mental health could be "piggybacked" onto longitudinal studies of their impact on general health and development. Because of limited study designs, little is known about the relationship between PUFA biomarker profiles and the onset of any psychiatric disorder or condition. Studies examining the possible association between the intake of omega-3 fatty acids, or the PUFA content of biomarkers, and the continuation or recurrence of psychiatric disorders or conditions were virtually nonexistent. If future research is going to produce data that are unequivocally applicable to North Americans, it will likely need to enroll either North American populations or populations exhibiting a high omega-6/omega-3 fatty acid intake ratio similar to what has been observed in the diet of North Americans. Furthermore if a reasonable view is that omega-3 fatty acids may play a role in mental health, then given the observed or proposed inter-relationships between omega-3 and omega-6 fatty acid contents both in the regular diet and in the human biosystem, it may behoove researchers to investigate the possible therapeutic or preventive value of the dietary omega-6/omega-3 fatty acid intake ratio.

Authors' methods: Systematic review

Project Status: Completed

URL for project: http://www.ahrq.gov/

Year Published: 2005

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: Agency for Healthcare Research and Quality

Contact Address: Center for Outcomes and Evidence Technology Assessment Program, 540 Gaither Road, Rockville, MD 20850, USA. Tel: +1 301 427 1610; Fax: +1 301 427 1639;

Contact Name: martin.erlichman@ahrq.hhs.gov

Contact Email: martin.erlichman@ahrq.hhs.gov

Copyright: Agency for Healthcare Research and Quality (AHRQ)