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.
Pearson
P J K
PJ
Division of Respiratory Medicine, University of Nottingham, Clinical Science Building, Nottingham City Hospital, Nottingham NG5 1PB, UK.
Lewis
S A
SA
Britton
J
J
Fogarty
A
A
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