Department of Public
University of Helsinki, Finland
Dec 14, 2017
Original articles and systematic reviews
Flaws in the Cochrane review on "vitamin C supplementation and asthma" (published in 2001 and withdrawn in 2013). The review had severe errors in extraction of data and in data analysis and misled readers for a decade.
Letters and commentaries
vitamin C and EIB, and a secondary analysis of a published
The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis.
Allergy, Asthma & Clinical Immunology 2014;10:58
Three studies found that vitamin C decreased common cold induced asthma exacerbations or bronchial hypersensitivity.
Vitamin C and common cold-induced asthma: a systematic review and statistical analysis.
Allergy, Asthma Clin Immunol 2013;9:46
Three studies found that vitamin C halved the FEV1 decline caused by exercise.
Vitamin C may alleviate exercise-induced bronchoconstriction: a meta-analysis.
BMJ Open 2013;3:e002416
Vitamin C was reported to alleviate asthma severity in Egyptian children, but the data set was found to be flawed.
Still the Egyptian study indicates that the effect of vitamin C should be further studied,
even though the validity of these particular findings is not clear.
Hemila H, Al-Biltagi M, Basset AA
Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.
Clin Transl Allergy 2011;1:9
Postpublication problems: reasons for the retraction:
See also retraction of the initial publication on which the above 2011 subgroup analysis was based:
of 3 exercise-induced asthma trials and pointing out errors in the
This was expanded to BMJ Open paper in 2013, see above
Hemila H. Feedback [Comments on the Cochrane review “vitamin C supplementation for asthma” by Kaur B, Rowe BH, Stovold E]
Cochrane Database of Systematic Reviews, Feedback 24 March 2009
The above comment was submitted in 2009, but the authors replied no earlier than in 2012.
Furthermore, the reply was full of errors:
Vitamin C and exercise-induced bronchoconstriction:
further problems in the Cochrane review "vitamin C for asthma" (2013).
The Cochrane review on vitamin C and asthma misled readers for a decade from 2001 to 2013.
See the PubMed records of the Cohrane review on vitamin C and asthma from 2001 to 2013:
http://www.ncbi.nlm.nih.gov/pubmed/24155047 2013 Withdrawal of the Cochrane review
Hemila H. Vitamin
C should be tested against exercise-induced bronchoconstriction.
Hemila H. Vitamin C and exercise-induced bronchoconstriction in athletes.