CV benefits of fish oil may have been overestimated
MedWire News: German researchers say that the benefits of omega-3 fatty acids in survivors of acute myocardial infarction, beyond those achieved with modern guideline-adjusted therapy, may have been overestimated.
In a 1-year follow-up study (OMEGA), Bernhard Rauch (Ludwigshafenan der Universität, Bremserstrasse, Germany) and colleagues demonstrated that guideline-adjusted treatment for acute myocardial infarction resulted in low rates of sudden cardiac death and other clinical events, but that additional supplementation of omega-3 fatty acids caused no further reduction in event rates.
For the purpose of the OMEGA study, the researchers randomly assigned 3851 survivors of acute myocardial infarction to receive omega-3-acid ethyl esters-90 (1 g/day) or an olive oil placebo (1 g/day) on top of current guideline treatment, between October 2003 and June 2007.
After 12 months of therapy, the team followed up 98.8% of survivors, and measured rates of sudden cardiac deaths, total mortality, major adverse cerebrovascular and cardiovascular (CV) events, and revascularization.
As reported in the journal Circulation, the rate of sudden cardiac deaths was 1.5%, and no significant difference was seen between the omega and control groups for total mortality rates (4.6% and 3.7%, respectively), or major adverse cerebrovascular and CV events (10.4% and 8.8%, respectively).
In addition, the frequency of revascularization procedures and the rates of rehospitalizations were similar for both study groups.
Rauch's team says: "The results of the OMEGA study call for a critical review of a potential benefit of omega-3 fatty acids under the conditions of current guideline-adjusted therapy of acute myocardial infarction."
They add that the potential beneficial effects of omega-3 fatty acids may previously have been overestimated.
In an accompanying editorial, Robert Eckel (University of Colorado, Aurora, USA) noted that during the study, fish consumption increased significantly in both groups.
"Although the number of subjects who consumed fish several times a week increased from 30% to 45% during the study interval, the projected increase in omega-3 fatty acids by [around] 1 g weekly would be an unlikely explanation as to why the omega-3 group failed to benefit from the intervention," he said.
He suggested that more powerful studies may be needed, with higher doses of omega-3 fatty acids, to investigate whether diets that include fish reduce the risk for recurrent CV disease.
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By Nikki Withers