Article Text
Abstract
Background: Epidemiological evidence from observational studies has suggested that blood levels and dietary intake of selenium of adults with asthma are lower than those of controls. The only previous trial of selenium supplementation in adults with asthma found no objective evidence of benefit but involved only 24 participants.
Methods: A randomised, double blind, placebo-controlled trial of selenium supplementation was performed in adults with asthma in London, UK, the majority of whom (75%) reported inhaled steroid use at baseline. 197 participants were randomised to receive either a high-selenium yeast preparation (100 µg daily, n = 99) or placebo (yeast only, n = 98) for 24 weeks. The primary outcome was asthma-related quality of life (QoL) score. Secondary outcomes included lung function, asthma symptom scores, peak flow and bronchodilator usage. Linear regression was used to analyse the change in outcome between the two treatment arms by “intention to treat”.
Results: There was a 48% increase in plasma selenium between baseline and end of trial in the active treatment group but no change in the placebo group. While the QoL score improved more in the active treatment group than in the placebo group, the difference in change in score between the two groups was not significant (−0.05 (95% CI −0.19 to 0.09); p = 0.47). Selenium supplementation was not associated with any significant improvement in secondary outcomes compared with placebo.
Conclusions: Selenium supplementation had no clinical benefit in adults with asthma, the majority of whom were taking inhaled steroids.
- COPD, chronic obstructive pulmonary disease
- FEF, forced expiratory flow
- FEV1, forced expiratory volume in 1 s
- FVC, forced vital capacity
- GPx, glutathione peroxidase
- PEF, peak expiratory flow
- QoL, quality of life
- RBC, red blood cell
- SELINA, SELenium IN Asthma
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Footnotes
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Published Online First 17 January 2007
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SS, PB and MR conceived and designed the study; SS supervised and had overall clinical responsibility for the project and drafted the manuscript; JP coordinated the project and was responsible for project documentation; AW and MT carried out all the fieldwork; RN carried out the power calculations and statistical analyses; MR gave advice on selenium measurement and supplementation; FK supervised measurement of vitamin E and GPx; PW gave advice regarding recruitment of participants through local general practices; JP assisted with data management; all authors revised or commented on the draft manuscript.
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This study was carried out as part of the research programme funded by the Department of Health’s Policy Research Programme. SOS is an Asthma UK Senior Research Fellow.
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Competing interests: None.
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