Hasselmark 1993.

Methods	Randomised, double‐blind trial. Run‐in phase: 4 weeks.
Participants	A total of 24 patients (12 in each group) suffering from intrinsic asthma (14 men, 10 women) with age ranged between 18 and 75 years were selected for the study. Of these patients 7 had intolerance to non‐steroid anti‐inflammatory drugs which had been verified by challenge test or typical history. Patients with atopic disease were excluded from the study. Exclusion criteria were also acute or recent infections of less than 3 weeks and somatic diseases of clinical importance. None of the patients had received treatment with oral corticosteroids or antibiotics, or take any lipid preparation less than 3 months before the study. Nor had the patients taken any selenium or vitamin E tablets during the previous 6 months.
Interventions	100mcg sodium selenite or placebo, BID for 14 weeks
Outcomes	Symptoms (in house scale); medication usage; vital capacity and FEV1. Regular measurement were also made of serum selenium concentrations and of GSH‐Px activity in platelet
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	Information not available (Cochrane Grade B)

BID = once daily