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Respirology. 2008 Jun;13(4):528-36. doi: 10.1111/j.1440-1843.2008.01286.x. Epub 2008 Apr 10.

Observational studies on the effect of dietary antioxidants on asthma: a meta-analysis.

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Department of Respiratory Diseases, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.



It has been suggested that the rapid increase in asthma prevalence may in part be due to a decrease in the intake of dietary antioxidants, including vitamin C, vitamin E and beta-carotene. Epidemiological studies investigating the association between dietary antioxidant intake and asthma have generated inconsistent results. A meta-analysis was undertaken to examine the association between dietary antioxidant intake and the risk of asthma.


The MEDLINE database was searched for observational studies in English-language journals from 1966 to March 2007. Data were extracted using standardized forms. Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using a random effects model. Ten studies were eligible for inclusion. Seven studies, comprising 13 653 subjects, used asthma or wheeze as their outcome; three studies explored the effect of antioxidant intake on lung function.


A higher dietary intake of antioxidants was not associated with a lower risk of having asthma. The pooled OR for having asthma were 1.06 (95% CI: 0.79-1.43) for subjects with a higher dietary vitamin C intake compared with those with a lower intake; 0.88 (95% CI: 0.61-1.25) for vitamin E; and 1.12 (95% CI: 0.77-1.62) for beta-carotene. There was no significant association between dietary antioxidant intake and lung function except for a positive association between vitamin C intake and an increase in FEV(1) (29.1 mL, 95% CI: -0.4-58.6, P = 0.05).


This meta-analysis does not support the hypothesis that dietary intake of the antioxidants vitamins C and E and beta-carotene influences the risk of asthma.

[Indexed for MEDLINE]

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