The Rainbow of Benefit, Including Heart Attacks, Rheumatoid Arthritis and Lupus
'Old people don't need companionship. They need to be isolated and studied so that it can be determined what nutrients they have that might be extracted for our personal use.' Homer Simpson
Heart attack prevention - the meta-analyses
To my mind the evidence that eating oily fish, or taking a fish oil supplement, protects people from heart attacks has been strong for quite some time. Nevertheless, on April 1 2006, a meta-analysis by Dr Lee Hopper and colleagues, published in the British Medical Journal, concluded the very opposite. In their words, "The pooled estimate showed no strong evidence of reduced risk of total mortality or combined cardiovascular events in participants taking additional omega-3 fats." They concluded that long chain and shorter chain omega-3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer."
Have I been wrong in my conclusions over the years? I don't think so. Yet I do think the study is in itself a wake-up call to governments to do sponsor additional studies, in particular a high quality double blind controlled population study that compares fish oil, and concentrated omega-3s, to aspirin in heart attack and mortality prevention.
A year earlier a meta-analysis by Mozaffarian and Rimm, published by the Journal of the American Medical Association, concluded the very opposite, concluding that eating fish, or taking fish oil, was indeed protective - and with little or no side effects.
Why the differences in the two conclusions. I think an editorial by Deckelbaum and Akabas, published in the American Journal of Clinical Nutrition to accompany a third meta-analysis of the benefits of fish or fish oil supplements, is indicative:
"The authors correctly propose that a meta-analysis of this topic is not possible because of the heterogeneity of study designs, background diets, endpoint definitions, and baseline fish or omega-3 intakes."
The meta-analysis referred was the 2006 study reported by Wang and colleagues, which concluded, "Most cohort studies reported that fish consumption was associated with lower rates of all-cause mortality and adverse cardiac outcomes… Evidence suggests that increased consumption of omega-3 fatty acids from fish or fish oil supplements, but not of alpha-linolenic acid [the vegetable omega-3], reduces the rates of all-cause mortality, cardiac and sudden deaths, and possibly stroke."
I agree with the major health authorities, including the American Heart Association and the UK NICE Committe, which continue to advocate fish or fish oil in heart attack prevention.