Vitamin D And Asthma

July 31, 2010

There have been several recent studies that indicate that vitamin D deficiency might have a negative impact on asthma.  The studies have mainly looked at true vitamin D deficiency defined as serum levels of 25-hydroxyvitamin D3 of less than 30ng/ml.  This can be measured by your doctor in a blood test.

Various studies have indicated that vitamin D supplementation in patients with low levels of vitamin D might prevent the development of wheezing in infants and young children, reduce asthma severity in patients with asthma and enhance the response of patients with asthma to inhaled steroids.

Studies looking at cohorts of infants followed from birth have shown that the higher the maternal vitamin D intake during pregnancy, the lower the risk of recurrent wheezing episodes and asthma in childhood.  The effect is felt to be a result of a lower risk of early childhood respiratory infections and wheezing noted in infants of mothers with higher vitamin D intake and infants with higher cord blood levels of vitamin D.

The National Health and Nutrition Examination Survey (NHANES) is a program of studies by the CDC looking at the health and nutritional status of adults and children in the United States.  Analysis of the Third NHANES showed that those with vitamin D deficiency with levels less than 10ng/ml had a higher risk of upper respiratory tract infections compared to individuals with normal vitamin D levels over 30ng/ml.  Also of interest in this survey is the fact that the difference was greatest in people with asthma.  Upper respiratory tract infections are a major cause of exacerbation of asthma in all age groups and a major cause of wheezing episodes in infants.

Several studies have shown that asthmatics with normal levels of vitamin D respond better to in haled steroids compared to asthmatics with vitamin D deficiency.  This enhanced steroid responsiveness would theoretically mean that those without vitamin D deficiency would require less medication than those with vitamin D deficiency to obtain the same level of asthma control.

More studies are needed to fully understand how vitamin D impacts asthma.  For now though, it seems reasonable to me that individuals with 25-hydroxyvitamin D3 levels less than 30ng/ml could benefit from vitamin D supplementation either through changes in dietary habits or the use of vitamin supplements themselves.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


2 Responses to “Vitamin D And Asthma”

  1. toby lee Says:

    Take a look at There is now a lot of data suggesting asthma is a vitamin D deficiency disease and vitamin d supplements dramatically reduce the number of asthma attacks. Most have levels less than optimal. The site also has links to a micropil formulation of vitamin D that only costs 10-12 for a years supply.

    • Yes, I am aware of the studies which is why I think it is reasonable to test and supplement if deficient. It definitely appears that true deficiency of vitamin D is not good for asthma and impacts wheezing frequency in infants and young children. However, I think there needs to be more research so that we can understand better why that is the case and whether or not it is a true cause and effect, or related to another process such as susceptibility to infection.

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