Last week, news headlines announced clinical trial results that seem likely to confuse many people.
In fact, they represent a kind of red herring ... that is, a clue that misleads or distracts the reader.
The news concerned a year-long clinical trial in people who’d just suffered their first heart attack.
To test whether omega-3s would add benefits to those seen with drug therapy, some of the participants also took fish oil over the 12 month period of the trial.
The authors of the German study found that when heart attack survivors took fish oil for one year in addition to “optimal” conventional therapy ─ surgery followed by daily doses of several cardiac drugs ─ they did not enjoy reduced risks of a second heart attack, stroke, or death within one year.
However, three prior clinical trials of similar design showed that supplemental fish oil can cut substantially reduce the risk of heart-related death … especially the most common, heart-beat related kind, called “sudden cardiac death.” (Lee JH et al. 2008)
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Key Points
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Heart attack survivors who added fish oil to “optimal” drug therapy gained no extra risk reductions after one year.
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The findings contradict those of several previous, and larger, clinical trials.
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The study’s authors attribute the variation to advances in drug therapy.
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The results don't change the overwhelmingly positive nature of all the available evidence.
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All of the drugs used in the “cardiac cocktail” come with adverse side effects and interactions, making longer-term use riskier than taking one or two drugs, and far riskier than fish oil.
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The largest previous clinical trial (GISSI-Prevenzione) ─ which involved 11,000 participants taking standard cardiac drugs plus fish oil ─ found a huge 40 percent reduction in sudden cardiac deaths, versus drug therapy alone.
Those results which match those of a major statin drug trial, suggest that omega-3s can be as effective as those common drugs (Marchioli R et al. 2001; Marchioli R et al. 2007; Tonkin AM et al. 2006).
In fact, the overwhelming majority of evidence supports the current medical consensus, which holds that omega-3-rich diets help protect cardiac health … and reduce the risk of dying from cardiovascular disease (CVD).
When the scientists who co-authored the current American Heart Association recommendations reviewed all of the evidence in 2006, they reaffirmed the association’s position in favor of omega-3s: “… most epidemiologic studies and randomized controlled trials have provided strong evidence of a cardio-protective effect of [omega-3] fatty acids.” (Gebauer SK et al. 2006)
The prior, positive clinical trials showed that heart attack survivors who take fish oil capsules suffer fewer cardiac-related deaths and second heart attacks. (Fish oil is not yet proven to reduce the risk of a first heart attack.)
And related research shows additive reductions in major heart-risk factors when people add fish oil to statin drug therapy.
For example, two recent trials in patients with high blood fat and non-HDL cholesterol levels showed that fish oil plus simvastatin (Zocor™) improved blood fat profiles more than simvastatin alone (Davidson MH et al. 2007; Maki KC et al. 2008).
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What do omega-3s do, exactly?
World and U.S. researchers agree that omega-3s reduce the risk of strokes, sudden cardiac death, and second heart attacks, by doing several things.
Some of these cardio-related omega-3 effects are better documented than others, and there they are, in rough descending order of the strength of the current consensus:
Well-documented effects with clinical evidence
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Lower blood triglyceride (fat) levels.
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Raise levels of “good” (HDL) cholesterol.
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Lower levels of all other forms of cholesterol*.
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Reduce risk of arrhythmia (erratic heart rhythms)**
Animal and/or lab evidence only or primarily
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May stabilize arterial plaque by moderating inflammation.
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May reduce oxidation of cholesterol into dangerous forms.
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May reduce accumulation of fat in the main coronary artery (aorta).
*Having high blood levels of all non-HDL cholesterol predicts risk of arteriosclerosis better than high LDL levels do alone. After LDL-lowering treatment goals have been reached, reduction of total non-HDL cholesterol is a recommended secondary treatment target in patients with high triglyceride levels (200 mg/dl or more).
**Sudden cardiac death results when heart rhythms go haywire. Omega-3s and certain cardiac drugs stabilize heart rhythms.
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These facts explain why the American Heart Association urges everyone to enjoy two servings of fish a week and advises heart patients to take 1000 mg of supplemental fish oil daily.
These were the conclusions of the most recent AHA Scientific Statement on fish and fish oil for heart health: “Omega-3 fatty acids have been shown in epidemiological and clinical trials to reduce the incidence of CVD [cardiovascular disease].” (Kris-Etherton PM et al. 2002)
And the AHA’s 2002 statement was specific about the intake levels needed, saying that people who take 5 grams to 1.8 grams daily (either as fatty fish or supplements) significantly reduce their risk of dying from heart-related reasons or any others.
It appears highly unlike that the unusual results of the new trial will change that advice, for several reasons.
Why the German findings don’t change the overall picture
Three things help explain the new study’s failure to find extra benefits when fish oil is added to optimal conventional therapy:
1. Drug therapy for heart attack survivors has advanced since the prior, clearly positive clinical trials were published … a point made by the German researchers themselves.
2. The trial’s one-year duration was short, in terms of the time it takes for cardiovascular disease to worsen again following the surgical interventions many of the patients received.
3. The German trial excluded anyone who’d already been taking fish oil, to narrow the findings to people who only start taking fish oil after a heart attack. However, omega-3s accumulate in tissues over time, and affect several of the processes that cause heart disease to gradually progress.
Given these factors, it makes no sense to assume that the German team’s negative findings extend to the value of omega-3s as a longer-term preventive agent … a point made by lead author Jochen ...
