Letters to the Editor

Vitamin C for Preventing Exercise-Induced Asthma

Am Fam Physician. 2012 Jun 1;85(11):1018.

Original Article: Exercise-Induced Bronchoconstriction: Diagnosis and Management

Issue Date: August 15, 2011

Available at: http://www.aafp.org/afp/2011/0815/p427.html

to the editor: I would like to point out an easy, low-risk preventive therapy that the article on exercise-induced bronchoconstriction did not mention. Ascorbic acid (vitamin C) taken before exercise can be protective against exercise-induced asthma in some persons.1,2 The effective dose is 1,500 to 2,000 mg one hour before exercise. This therapy does not replace the need to have an albuterol inhaler available.

Author disclosure: No relevant financial affiliations to disclose.

REFERENCES

1. Cohen HA, Neuman I, Nahum H. Blocking effect of vitamin C in exercise-induced asthma. Arch Pediatr Adolesc Med. 1997;151(4):367–370.

2. Schachter EN, Schlesinger A. The attenuation of exercise-induced bronchospasm by ascorbic acid. Ann Allergy. 1982;49(3):146–151.

in reply: Thanks to Dr. Stevenson for mentioning the use of ascorbic acid as a protective agent in the management of exercise-induced asthma. Many different types of therapies have been used, from inhaled heparin to verapamil. I tried to limit this article to therapies with strong evidence-based support.

The studies Dr. Stevenson mentions are intriguing but have several deficiencies. The first deficiency is the number of participants in the study. The Cohen article1 had only 20 participants, and the Schachter study2 had only 12 participants. Another problem is that neither study uses exercise challenge testing protocols, which have been shown to be more sensitive and specific in detecting exercise-induced asthma. Lastly, the Cochrane Collaboration reviewed vitamin C supplementation for the treatment of asthma most recently in 2009.3 Both of these studies were found to have flaws in reporting quality, and the reviewers concluded that the evidence was insufficient to support the use of vitamin C in the management of asthma.

Although many possibly cheaper and simpler treatments may be useful in the management of exercise-induced asthma, physicians should favor evidence-based treatments until these other treatments have stronger evidence to support their use.

Author disclosure: No relevant financial affiliations to disclose.

REFERENCES

1. Cohen HA, Neuman I, Nahum H. Blocking effect of vitamin C in exercise-induced asthma. Arch Pediatr Adolesc Med. 1997;151(4):367–370.

2. Schachter EN, Schlesinger A. The attenuation of exercise-induced bronchospasm by ascorbic acid. Ann Allergy. 1982;49(3):146–151.

3. Kaur B, Rowe BH, Arnold E. Vitamin C supplementation for asthma. Cochrane Database Syst Rev. 2009(1):CD000993.

Send letters to Kenneth W. Lin, MD, MPH, Associate Deputy Editor for AFP Online, e-mail: afplet@aafp.org, or 11400 Tomahawk Creek Pkwy., Leawood, KS 66211-2680.

Please include your complete address, e-mail address, and telephone number. Letters should be fewer than 400 words and limited to six references, one table or figure, and three authors.

Letters submitted for publication in AFP must not be submitted to any other publication. Possible conflicts of interest must be disclosed at time of submission. Submission of a letter will be construed as granting the American Academy of Family Physicians permission to publish the letter in any of its publications in any form. The editors may edit letters to meet style and space requirements.


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