In the last twelve months, multiple studies have shown a connection between Vitamin D and asthma. Initially, studies demonstrated that Vitamin D deficiency may be a significant causative factor in the development of the condition. More recently, clinical trials have shown that those with higher Vitamin D levels show an improved patients response to standard asthma treatments and Vitamin D supplements significantly reduce the number and severity of asthmatic attacks in children.

Summary of Findings

  • low levels of Vitamin D are associated with increasing severity of asthma in children. (171)

  • asthamtic children with low Vitamin D levels use more inhaled steroids and experience more hospitalizations than those with higher levels. (171)

  • decreased lung function is shown to correlate with low Vitamin D levels in adult asthmatics. (173)

  • asthmatic patients with low vitamin D levels do not respond to corticosteroids as well as those with higher vitamin D levels .(173)

  • The action of steroids on inflammatory cells taken from patients with asthma were enhanced tenfold by the presence of Vitamin D. (174)

  • children taking Vitamin D supplements had a six-fold reduction in the number of asthma attacks compared to those on placebo. (175)


A study published in the American Journal of Respiratory and Critical Care Medicine, (April 2009) suggested that low levels of Vitamin D may be linked to severity of asthma in children. (171)

The study examined the blood levels of Vitamin D in children with asthma and found that lower levels of Vitamin D were associated with more severe asthma.

Participants included 616 children with asthma between the ages of 6 and 14. Of the participants, 175 had insufficient levels of Vitamin D. John Brehm, MD, from Brigham and Women's Hospital, Boston, and colleagues found that low Vitamin D levels were associated with more asthma hospitalizations in the previous year, more airway hyperactivity in lung function tests, more use of anti-inflammatory asthma medications such as inhaled steroids in the previous year, and higher blood levels of allergy markers.

While the study did not confirm a cause-effect relationship, the researchers noted that Vitamin D may influence asthma in different ways, such as its effect on the immune system and muscle cells of the airways.

Then in January 2010, another study published in American Journal of Respiratory and Critical Care Medicine,(2) also demonstrated that low Vitamin D levels were associated with worse lung function compared to higher Vitamin D levels in people with asthma. Researchers compared Vitamin D levels and asthma severity in 54 people with asthma.

The results showed that people with higher Vitamin D levels had better lung function than people with lower Vitamin D levels. In particular, people with low Vitamin D performed worse on tests of lung function and airway hyper-responsiveness, two hallmarks of asthma.

Vitamin D levels were shown to be directly related to participants' score on the breathing tests: the lower the Vitamin D levels, the worse their performance.

For example, airway hyper-responsiveness was nearly twice as poor in people with Vitamin D insufficiency (below the threshold level of 30 nanograms/milliliter) as compared to those with higher Vitamin D levels.

In addition, the study showed that people with low Vitamin D levels didn't respond as well to asthma treatments, in particular, corticosteroids, as compared to people with higher Vitamin D levels.

The study also showed that low Vitamin D levels were associated with increased production of a pro-inflammatory protein in the blood, which raises the possibility that low vitamin D levels could be related to increased inflammation in people with asthma.

"Our findings suggest that Vitamin D levels influence a number of important features of asthma, including lung function, bronchospasm, and therapeutic response to steroids," researcher E. Rand Sutherland, MD, MPH, chief of the pulmonary division at National Jewish Health in Denver, said in a news release.

At the annual meeting of the American Academy of Allergy Asthma & Immunology in New Orleans Feb 27-March 2, 2010, preclinical data was reported that supported the clinical findings above that Vitamin D could dramatically reduce the need for steroids in asthma patients.   The action of steroids on inflammatory cells taken from patients with asthma were enhanced tenfold by the presence of Vitamin D. (174)

March 2010, a study published in the American Journal of Clinical Nutrition confirmed that Vitamin D can help the body ward off viral infections and asthma attacks.  More than 600 Japanese schoolchildren aged 6-15 were treated from December 2008 through to the end of March 2009 with Vitamin D (1200 IU per day) or placebo (175)

The number of infections with the viruses influenza A and B and the number of asthmatic attacks were assessed. Of note is the fact that influenza A includes the H1N1 strain that was responsible for the pandemic alerts of last year.   

Whether a child had succumbed to influenza over the course of the study was confirmed microbiologically using swabs from the nose/throat.   

Those children taking Vitamin D developed 42 percent fewer infections with influenza B.  The benefits were even more dramatic in children who had not been previously supplementing with Vitamin D, and in these children there was a 64 percent reduction in the infection rate. 

Even more interesting was the reduction in the number of children developing asthma attacks.  Those children taking Vitamin D supplements had a six-fold reduction in the number of asthma attacks compared to those on placebo. This difference was found to be highly statistically significant P<0.006) .   

In summary, this was a placebo controlled trial--the gold standard of clinical research-- that demonstrated up to a 60% reduction in the incidence of viral infections and a six-fold reduction in the incidence of asthma attacks. 

Of note is the fact that the dose of Vitamin D3 used, only 1200IU, is low compared to the current recommendations of Vitamin D experts. In addition, the clinical trial only ran for three months, and it can take many months of supplementation to improve Vitamin D levels. Although actual Vitamin D levels were not measured in this study, the relatively low dose used and short study duration would suggest that many of the children would not have reached anywhere near optimal levels of Vitamin D during the trial. Still,the results were dramatic. 


(171) Serum Vitamin D Levels and Markers of Severity of Childhood Asthma in Costa Rica. American Journal of Respiratory and Critical Care Medicine Vol 179. pp. 765-771, (2009) John M. Brehm1–3*, Juan C. Celedón1–4*, Manuel E. Soto-Quiros5, Lydiana Avila5, Gary M. Hunninghake1–3, Erick Forno1,3,6, Daniel Laskey1, Jody S. Sylvia1, Bruce W. Hollis7, Scott T. Weiss1,3 and Augusto A. Litonjua1–4 

(173) Vitamin D Levels, Lung Function and Steroid Response in Adult Asthma. Am J Respir Crit Care Med. 2010 Jan 14. Sutherland ER, Goleva E, Jackson LP, Stevens AD, Leung DY.

(174) AAAAI: Vitamin D Levels Linked to Asthma Meds. Crystal Phend, Senior Staff Writer, MedPage Today
Published: February 27, 2010  Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston.

(175) Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr 10th March 2010. Urashima M, et al.



The products and the claims made about specific products on this site have not been evaluated by the United States Food and Drug Administration and are not intended to diagnose, treat, cure or prevent disease. The information provided on this site is for informational purposes only and is not intended as a substitute for advice from your physician or other health care professional. You should consult with a healthcare professional before starting any diet, exercise or supplementation program, before taking any medication, or if you have or suspect you might have a health problem.  


    Vitamin D in Asthma