Omega-3 Enriched Margarines Do Not Protect From Subsequent Heart Attacks

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Main Category: Nutrition / Diet
Also Included In: Cardiovascular / Cardiology;  Heart Disease
Article Date: 29 Aug 2010 - 7:00 PST

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Men and women who had a myocardial infarction (heart attack) and regularly consume Omega-3 (N-3 fatty acids) enriched margarines do not have a lower risk of subsequent cardiovascular events, such as a heart attack, according to a presentation made by researchers at the European Society of Cardiology Congress 2010, Stockholm, Sweden.

In their study, investigators gave patients 400 mg per day supplement of the fish oil fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) and 2 grams of the plant-derived fatty acid alpha-linolenic acid (ALA) in enriched margarines. They found that there was no overall reduction in the risk of major cardiovascular events.

Among one of the sub-groups in their study, investigators report that there was a borderline significant reduction in major cardiovascular events in females who took ALA, as well as in patients with diabetes. They add that n-3 fatty acids protected against ventricular arrhythmia-related events.

Omega-3 (N-3) fatty acids are divided into two main types:

• From fish - EPA (eicosapentaenoic acid)
• From plant foods, such as walnuts and soybean oil - DHA (docosahexaenoic acid)

Team leader, Professor Daan Kromhout from Wageningen University, the Netherlands, said:

Several intervention studies in cardiac patients have shown that a daily intake of 1-2 grams of EPA + DHA via fish oil capsules reduced mortality from coronary heart disease by 20%.

Epidemiological studies in healthy populations have also suggested that 250 mg EPA + DHA or eating fish once or twice a week can lower the risk of CVD by a similar amount. For ALA, there is less evidence of a cardioprotective effect. We designed the Alpha Omega Trial as a dietary intervention study to examine the effect of low doses of n-3 fatty acids on major cardiovascular events.

The study (trial) involved 4,837 male and female participants aged between 60 and 80 years. All of them had had a heart attack (myocardial infarction) about four years before the start of the study.

They were randomly selected to consume one of the following enriched margarines daily for 40 months:

• Margarine containing extra EPA + DHA (400 mg/day)
• Margarine containing extra ALA (2 g/day)
• Margarine containing extra EPA + DHA and ALA
• Margarine with a placebo

In all four treatment groups, the margarines looked and tasted the same. Participants used them on bread instead of their usual margarine or butter. Compliance and double-blinding were maintained throughout the trial.

The trial ended in November 2009. Its primary endpoint (the main result that is measured at the end of a study to see if a given treatment worked; what the researchers were mainly looking out for) was major cardiovascular events (MACE) of morbidity and mortality, and cardiac procedures (PCI and CABG).

Key secondary endpoints were fatal coronary heart disease and ventricular arrhythmia-related events defined as sudden death, cardiac arrest and cardiac arrest and cardioverter-defibrillator placement.

Professor Kromhout said:

The patients in this trial were very well treated. with 98% on antithrombotic agents, 90% on antihypertensive drugs, and 86% on lipid lowering drugs. We found that cardiovascular mortality rate in the study population was only half that expected, probably because of their excellent treatment. This may also be why the rate of major cardiovascular events during follow-up was no lower in the fatty acid groups than in the placebo group.

However, we did see a 27% borderline significant reduction in primary endpoint in women who received ALA. We also carried out an exploratory analysis in patients with diabetes, and this showed a significant 50% reduction in CHD mortality in patients who received EPA + DHA. For both, EPA + DHA and ALA a similar 50% reduction was observed in the number of arrhythmia-related events in diabetic patients.

Source: European Society of Cardiology Congress 2010

Written by Christian Nordqvist
Copyright: Medical News Today
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