Vitamin E supplements in asthma: a parallel group randomised placebo controlled trial.
BACKGROUND
Increased dietary vitamin E intake is associated with a reduced incidence of asthma, and combinations of antioxidant supplements including vitamin E are effective in reducing ozone induced bronchoconstriction. A study was undertaken to investigate the effect of supplementation with vitamin E for 6 weeks on bronchial hyperresponsiveness in atopic adults with asthma.


METHODS
72 participants from a clinical trial register of adults with asthma were randomised to receive 500 mg natural vitamin E or matched placebo for 6 weeks in a placebo controlled, double blind parallel group clinical trial. Inclusion criteria included age 18-60 years, maintenance treatment of at least one dose of inhaled corticosteroid per day, a positive skin prick test to one of three common allergens, and bronchial hyperresponsiveness to methacholine (defined as a dose provoking a 20% fall in forced expiratory volume in 1 second (FEV(1)) (PD(20)) of 12.25 micromol). Secondary outcomes were FEV(1), forced vital capacity, mean morning and evening peak flow, symptom scores, bronchodilator use, and serum immunoglobulin E levels.


RESULTS
In the primary intention to treat analysis the change in PD(20) was similar in the vitamin E and placebo groups with a mean difference of +0.25 doubling doses of methacholine (95% confidence interval -0.67 to +1.16 greater with vitamin E). There was no effect of vitamin E supplementation on any other measure of asthma control, either in the intention to treat or per protocol analysis. There was also no effect of vitamin E supplementation on serum immunoglobulin levels.


CONCLUSIONS
Dietary supplementation with vitamin E adds no benefit to current standard treatment in adults with mild to moderate asthma.
Division of Respiratory Medicine, University of Nottingham, Clinical Science Building, Nottingham City Hospital, Nottingham NG5 1PB, UK.
P J K
PJ
Pearson
S A
SA
Lewis
J
J
Britton
A
A
Fogarty
D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000178:diet therapy / Q000503:physiopathology / Q000517:prevention & control*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014797:Vital Capacity / Q000502:physiology; D014810:Vitamin E / Q000008:administration & dosage*
D014810:Vitamin E