Study designs of evaluations included in the review
Randomised controlled trials (RCTs) with a follow-up of at least 1 year were eligible for inclusion. The included studies followed up participants from 1.4 to 8.2 years on average.
Specific interventions included in the review
Studies of vitamin E supplementation alone, or in combination with other vitamins or minerals, for the duration of at least 1 year were eligible for inclusion. The vitamin E dosage ranged from 16.5 to 2000 international units per day (IU/per day), with a median dose of 400 IU/day. Most of the included studies were placebo-controlled. More than half of the studies evaluated vitamin E combined with other vitamins or minerals such as vitamin C and beta-carotene. Further details were given.
Participants included in the review
Studies of men or non-pregnant women were eligible for inclusion. Most of the studies included participants who were at high-risk for a chronic disease, most frequently coronary heart disease. The mean age ranged from 47 to 84 years, where reported.
Outcomes assessed in the review
Studies that evaluated all-cause mortality and reported at least 10 deaths were eligible for inclusion.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.