Evidence-based management of EIB with vitamin C
Smoliga, Weiss and Rundell reviewed exercise-induced bronchoconstriction (EIB) and implied in their title that they covered evidence-based managements of EIB.
EBM requires that the literature searches should be thorough, and RCTs and systematic reviews should be the primary focus of the searches. There are 3 RCTs on vitamin C and EIB and the pooled relative effect estimate indicates a 48% reduction (95% CI 33% to 64%) in the postexercise FEV1 decline when vitamin C was administered before exercise [1,2]. These findings were not mentioned by Smoliga et al.
A subcommittee of the American Thoracic Society wrote guidelines about EIB and in the guidelines mentioned 2 RCTs about vitamin C . I pointed out that a third RCT had been ignored in the guidelines, and I also pointed out that the statistical analysis of the 2 included RCTs was superficial, eg 95%CIs were not calculated . Rundell was an author of the guidelines  and thus knew that there are RCTs on vitamin C and EIB.
Dismissing the evidence about vitamin C for EIB may be explained by the bias in mainstream medicine against treatments that do not need prescriptions .
1. Hemilä H.Vitamin C may alleviate exercise-induced bronchoconstriction: a meta-analysis. BMJ Open 2013;3:e002416 http://dx.doi.org/10.1136/bmjopen-2012-002416
2. Hemilä H. The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis. Allergy, Asthma and Clinical Immunology 2014;10:58 http://dx.doi.org/10.1186/1710-1492-10-58
3. Parsons JP, et al. An official American Thoracic Society clinical practice guideline: exercise-induced bronchoconstriction. AJRCCM 2013;187:1016-1027. http://dx.doi.org/10.1164/rccm.201303-0437ST
4. Hemilä H. Vitamin C should be tested against exercise-induced bronchoconstriction. AJRCCM 2013;188(11):1370. http://dx.doi.org/10.1164/rccm.201307-1205LE
5. Louhiala P, Hemilä H. Can CAM treatments be evidence-based? Focus on Alternative and Complementary Therapies 2014;19(2):84-89 http://dx.doi.org/10.1111/fct.12110
Competing interests: No competing interests