A recent review of medical literature suggests that vitamin D deficiency may be linked to asthma.
Vitamin D is found in foods, such as eggs, fish and fortified milk. It is also produced in the body after sun exposure. Adequate vitamin D levels are necessary for the body to absorb the essential minerals calcium and phosphorus. It is also important for immune system function and healthy bones.
The review, published in Annals of Allergy, Asthma & Immunology, evaluated studies that were conducted between 1950 and 2009 and indexed on the PubMed database of the National Library of Medicine. The authors of the review surveyed studies that contained the following keywords: asthma, vitamin D, inflammation, airway smooth muscle and cytokines.
Overall, the studies suggested that vitamin D deficiency may be linked to airway inflammation, decreased lung function and poor asthma control. The review authors hypothesized that vitamin D supplementation may help improve asthma symptoms by preventing the release of inflammatory cytokines and increasing the secretion of anti-inflammatory proteins. Vitamin D is also thought to play a role in immune function, which may benefit patients with allergic asthma.
However, many of the studies included in the review were observational, and were not explicitly designed to test the effects of vitamin D supplementation on patients with asthma. Therefore, additional long-term trials are needed to determine exactly how vitamin D may affect the condition.
For more information about vitamin D, please visit Natural Standard's Foods, Herbs & Supplements database.