A recent study has cast doubt on the benefit of n-3 fatty acids for preventing cardiovascular complications in patients with type 2 diabetes (NEJM 2012; 367: 309-18).
While previous studies have indicated that persons who consume fish regularly or take supplements with n-3 fatty acids have a reduced risk of cardiovascular events, there are many potential confounding variables. This “ORIGIN” study (Outcome Reduction with an Initial Glargine Intervention) which had 12,611 patients undergo randomization looked at a high risk group (type 2 diabetes patients) but did not find any change in cardiovascular events, including death over a median followup of 6.2 years. The treatment group received 1 gram of n-3 fatty acids which did result in a lower triglyceride level (by 14.5 mg/dL).
How do the authors explain the results of this negative study in comparison to previous reports?
- Two of the largest trials had recruited patients with recent myocardial infarction –these patients may have been more likely to benefit
- In ORIGIN study, more concomitant cardioprotective therapies were being used which could have reduced the potential benefit of n-3 fatty acids
- Other study populations may have had a lower dietary intake of n-3 and therefore benefitted more from supplementation
While the results of this study may reduce the enthusiasm for n-3 fatty acids, several additional large studies (ASCEND/NCT00135226, VITAL/NCT01169259) are underway which should give additional information on this topic, including in participants at lower risk for cardiovascular events. In addition, the authors conclude that while their findings do not show a reduction in cardiovascular events, they state that dietary recommendations of increased fish consumption should not change; increased fish consumption not only increases n-3 fatty acids but results in lower intakes of red meats which may be harmful.
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