Effect of low doses of n-3 fatty acids on cardiovascular diseases in 4,837 post-myocardial infarction patients: Design and baseline characteristics of the Alpha Omega Trial

Background: Weekly fish consumption has been related to a lower risk of fatal coronary heart disease (CHD) and incident stroke in populations with a low fish intake. This relation has mainly been attributed to n-3 fatty acids in fish, that is, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It is at present unclear whether α-linolenic acid (ALA), a n-3 fatty acid from vegetable origin, could also be protective against cardiovascular diseases (CVDs). There is a need for food-based trials to establish the efficacy of low doses of n-3 fatty acids in CVD prevention. Objectives: The aim of the study was to evaluate the effect of an additional daily intake of 400 mg of EPA + DHA and 2 g of ALA on CVD morbidity and mortality in free-living subjects with a history of myocardial infarction. Design: The multicenter Alpha Omega Trial is a randomized, double-blind, placebo-controlled trial with a 2 × 2 factorial design. Between May 2002 and December 2006, we enrolled a total of 4,837 men and women aged 60 through 80 who experienced a myocardial infarction within 10 years before entering the study. Subjects were randomized to 1 of 4 margarine spreads that were enriched with EPA + DHA and/or ALA, or placebo. Compliance was monitored via tub counts and assessment of n-3 fatty acids in plasma. Subjects were observed for 40 months for the occurrence of fatal and nonfatal CVD. Results: The cohort was on average 69 years old at the start of the study and comprised 22% women. Subjects had their (last) myocardial infarction approximately 4 years before enrolment. Mean body mass index was 27.7 kg/m