Omega-3 v heart attacks.

Dr Daan Kromhout reported disappointing findings in a study of 4,800 heart attack survivors in Holland, who were assigned to one of 3 omega-3 options or a placebo.

They were randomly assigned use of one of four margarines on bread instead of their regular spread – one containing no extra omega-3 fatty acids – one with 400 milligrams a day of extra eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – one with 2 grams of alpha-linolenic acid (ALA); and one with a combination of EPA-DHA and ALA.

The omega-3 appeared to improve risk of a second heart attack initially, but by 30 months the benefit had either disappeared totally or was not clinically significant.

The authors suggest that outstanding medical treatment for the group, which had cut the risk for all by half, may have masked any omega-3 effect, although this idea has been criticised.

The study has also been criticised for using margarine rather than a capsule and for not providing information on weight or blood pressure.

The average consumption of fish in Holland is 3 times the average in the US, which may also affect how general the findings are.

Although it was not the focus of the study, the authors did find significant improvements in patients with diabetes who took EPA-DHA.