Randomised controlled trials (RCTs) that evaluated the effect of selenium supplements, either alone or in combination with other vitamins or minerals, for the prevention of cardiovascular disease (CVD) were eligible for inclusion. Studies had to report sufficient information about selenium exposure. The primary review outcome was CHD, defined as any combination of fatal or nonfatal CHD and myocardial infarction (MI). Studies reporting total cardiovascular outcomes were also included. The review excluded studies assessing angiographically-defined outcomes or angina pectoris and other cardiovascular outcomes such as heart failure, stroke, peripheral arterial disease and nonatherosclerotic heart disease.
All of the included studies were placebo-controlled and most evaluated selenium combined with other vitamins or minerals. The doses of selenium ranged from 75 to 200 μg/day. The duration of interventions ranged from 0.5 to 7.6 years. Studies were in patients with existing CHD (including those with acute MI), healthy adults, residents in a geographical area, and patients with skin cancer who did not have CVD. The mean age of the participants ranged from 47 to 62 years and 39 to 87% were male. The included studies assessed mortality from acute MI and CVD and the incidence of CHD and CVD.
Two reviewers independently selected the studies and resolved any disagreements by consensus.