By the end of 2007 the project was close to finish. Most of the workpackages have been completed, most results have been published in International peer-reviewed journals, but some results still have to be published. It is expected that the remainder of the results will be published in 2008. Until now, the effect of fish oil on heart health that was found was less positive then expected before hand. The clear positive effect that was seen so far is a lowering of the heart frequency. Also, the pig studies give some indications that fish oil may have positive effects in some animals. A summary of the project is given below (it is the same summary given in the third reporting period).
In this project, two large intervention studies on the effects of n-3 fatty acids from fish in capsules were performed on arrhythmia. Furthermore the project includes an intervention study on the bioconversion of alpha-linolenic acid to EPA and DHA and an experimental study in isolated pig hearts on the effect of n-3 fatty acids on electrophysiology. In the first intervention trial no significant effects of n-3 fatty acids could be detected in patients with arrhythmia, neither on spontaneous PVC’s (premature ventricular contractions), nor on changes in the ECG, which could imply that these markers are not sufficiently sensitive or specific to detect the beneficial effects of fish oil on the heart. Further analysis of the data revealed a decrease of the heart rate in the patients supplemented with the n-3 fatty acids. This effect is considered as favourable. The second intervention trial (multi centre; SOFA) has been executed in Western and Eastern Europe with in total 546 patients with an implanted defibrillator. The intervention was continued until January 2005 and data collection was completed in July 2005. Preliminary results have already been communicated at international meetings in Stocholm (European Society of Cardiology) and Durban (International Union of Nutrition Sciences) in September 2005. Results of the study were published in June 2006 in the Journal of the American Medical Association.
Experimental research performed in the Amsterdam Medical Center in isolated hearts of pigs fed n-3 fatty acids from fish indicated that, contrary to the hypothesis, during acute ischaemia a tendency for more ventricular tachy arrhythmias occurred in the hearts from n-3 fatty acids supplemented animals. In simple terms this means that the stability of the normal rhythm of heart muscle contracton is decreased following n-3 fatty acid supplementation. Moreover voltage clamp experiments on isolated myocytes from the animals described above, revealed a shorter action potential duration. One paper on these results has been published in 2006 in Cardiovascular Research, while another one is in press in the same journal. The intervention study on the bioconversion of alpha linoleic acid to EPA and DHA was succesfully completed at Maastricht University in 34 volunteers by June 2005. Results have been analyzed and a paper will be published.