Vitamin D and Asthma Control: What's the Connection?

  • Recently, a Facebook friend posted a link to an article about how low vitamin D levels had been linked to asthma flare-ups in a study done in Israel. After reading about the study, I decided to look for more information on this topic and to share with my readers what I had learned.


    What Is Vitamin D?


    Vitamin D is a nutrient that your body produces naturally when you are out in the sun, which is why it is sometimes called "the sunshine vitamin". You may also get smaller amounts of Vitamin D in the food you eat. For instance, dairy and grain products often have fortified Vitamin D in them. A few foods have naturally occuring Vitamin D in them, such as:

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    • certain types of fish
    • fish liver oils
    • egg yolks

    This nutrient plays a role in building strong, healthy bones, by helping your body use calcium correctly. It can also help maintain a healthy immune system. 


    A lack of enough Vitamin D has been linked to a number of health conditions, including asthma, heart disease and cancer.


    Who Is at Risk for Low Vitamin D?


    Lack of sun exposure: People who seldom spend time outdoors in daylight will likely have lower levels of this nutrient. But also people who live in northern and/or mostly cloudy climates, where the sun shines less often, may also have trouble making enough Vitamin D. Certain cultural or religious customs that prescribe wearing long coverings on the limbs may also limit your skin's exposure to the sun. And finally, people with dark skin sometimes suffer from low Vitamin D levels too.


    Insufficient nutritional sources: Those who are vegan may not get any Vitamin D from its mostly animal-based food sources. People who have poorly-functioning kidneys or digestive tracts may also have trouble using Vitamin D in the body. And finally, people who are obese may find that their excess fat cells prohibit the body from converting Vitamin D to a usable form.


    How Vitamin D Levels Affect Asthma


    Although experts aren't really sure at this point in time if Vitamin D levels play a role in causing asthma, studies do suggest that there is some kind of link in terms of managing asthma. Unfortunately, many of the studies done to date were not well-controlled or looked at relatively small numbers of participants.


    So, I was excited to learn about the Israeli study. It looked at over 300,00 people who had had their Vitamin D levels recorded. Out of those, 21,237 people had been diagnosed with asthma.


    Researchers controlled for sex, age, ethnicity, smoking and other factors that might have skewed results. What they found was that the lower a person's Vitamin D level, the more likely they were to have asthma attacks, or flare-ups.


    (An asthma attack is an increase in symptoms such as wheezing, chest tightness, cough, and shortness of breath, despite being on an asthma controller medication.)


    The study measured loss of asthma control by looking at prescriptions filled and number of physician visits.


    What they found:

    • 15 percent of people with readings between 0 and 10 nanograms per milliliter had at least one flare-up, while
    • only 12 percent of those with readings of 10 to 20 and 9 percent of those with readings above 36, a level generally considered adequate, had flare-ups

    So, Should We All Start Taking Vitamin D Supplements?


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    The jury is definitely still out on that question! So far, research has not strongly supported the idea that taking Vitamin D supplements has any significant effect on asthma control or the effectiveness of asthma medication. Some studies have suggested supplements may help, but they were not large enough or controlled enough to have sufficient validity.


    Vitamin D is not a dangerous nutritional supplement, so adding some to your intake, in moderation, would probably not be harmful. There is just no guarantee either that it would help prevent asthma flares. And you should certainly never take Vitamin D in lieu of your prescribed asthma medications.


    So, as is often the case, more study is needed. Hopefully, this latest Israeli study will lead to larger, more scientific studies on how to use Vitamin D in the right to control asthma.

Published On: November 09, 2014