Omega-3, heart health evidence is strong, says review

Omega-3 fatty acids have been linked to a wide-range of health benefits, including cardiovascular disease (CVD), good development of a baby during pregnancy, joint health, behaviour and mood, and certain cancers.

But some much publicised studies, and in particular a recent meta-analysis (British Medical Journal, doi: bmj.38755.366331.2F), have claimed that there was no evidence linking omega-3 intake and improvements in heart health.

The new review, published in the American Journal of Clinical Nutrition (Vol. 84, pp. 5-17), takes “a large step forward in helping to resolve the controversies related to the beneficial effects of omega-3 fatty acids on CVD outcomes,” according to Richard Dickelbaum and Sharon Akabas from Columbia University, in an independent editorial.

The problems with reviewing and pooling previous studies has come from the fact that many of the studies are not directly comparable, with long- and short-term trials being grouped together, and no separation made between primary and secondary prevention studies.

The new review, authored by Chenchen Wang and associates from Tufts-New England Medical Center, only considered studies that lasted for more than one year, and that reported or estimated omega-3 intakes and CVD outcomes. Care was taken to separate interventions using alpha-linolenic acid (ALA) from interventions using eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or EPA plus DHA.

“Most of the large cohort studies reviewed, which involved more than 340,000 participants in total, reported significant reductions after multivariate adjustment in one or more CVD outcomes of interest,” reported the reviewers.

The supplement trials considered by the researchers included EPA or EPA plus DHA in doses ranging from 0.27 to 4.8 grams per day. Five of the trials were consider to be of high standard, receiving grades A or B for their methodological quality.

The results from these studies were mixed, but the largest reported that a 0.85 grams per day supplement of EPA plus DHA was reported to reduce the risk of all-cause mortality by 21 per cent, cardiac death by 35 per cent, and sudden death by 45 per cent.

The editorial said that the study made a significant contribution to resolving the controversies with the subject.

“We believe that the body of existing evidence is strong enough to suggest that in the United States, certainly, and in other countries where omega-3 fatty acid consumption is low, public health initiatives are needed to increase intakes of EPA and DHA,” concluded Deckelbaum and Akabas.

Steve - this the first good example of a meta-analysis that was done properly. It concentrated on specific outcomes and specific trial duration.