An Archives of Internal Medicine "review" claims that fish oil and fish oil supplements showed no heart benefit in patients who already had a history of heart disease. Here's the problem with this conclusion.
- It goes against decades of data, including a "review" performed last year that showed the benefits of EPA and DHA for secondary heart prevention.
- A small reduction in cardiovascular death was shown, but disappeared after exclusion of a trial that had "major methodologic problems". Why would the researchers include a study in their meta analysis that had major methodologic problems?
- The authors themselves concede that their analysis is limited, especially in that they only analyzed trials with small populations and short durations.
- The authors performed a meta analysis, selecting 14 studies from 1007. Why so selective? Their reasoning was not convincing. This is yet another example of why one cannot make conclusions from meta analyses. There is precedence for authors who take liberties with meta analyses, especially if bias enters into the equation. Any researcher can prove a point from a substance as heavily researched as fish oil when selecting 14 studies from 1007!
- Time Magazine: "Findings don’t necessarily mean that omega-3s — the study looked at the fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) — are useless when it comes to preventive health. Indeed, the American Heart Association (AHA) recommends that both heart patients and those who don’t yet have heart disease eat fatty fish at least two times a week, and if they can’t consume that much fish, then to boost their omega-3 intake with supplements. According to the AHA, studies show that omega-3 fatty acids can decrease the risk of abnormal heartbeats, keep triglyceride levels down and inhibit the build up of atherosclerotic plaques in the heart’s blood vessels.
It’s also possible that Myung and his colleagues failed to see a strong positive effect from omega-3 supplements among people with pre-existing heart disease because these patients may need a higher level of omega-3s to see benefit. The researchers looked at a range of doses of EPA and DHA, but perhaps a scarred, damaged heart that has survived a heart attack or angina is affected differently by omega-3 fatty acids than an intact and healthy heart.As Harvard researchers Drs. Frank Hu and JoAnn Manson also point out in a commentary accompanying the new study, it’s possible too that drugs like statins may mask the benefit from fish oils because the medications are so much more powerful. That may also explain why older trials have tended to show a fish oil benefit, while newer ones have not."
- MedPage Today: "The findings are at odds with analyses performed before 2010, which showed a significant benefit for secondary prevention, the authors added."