In the past few years, researchers have found several possible links to health conditions and low levels of vitamin D. According to studies, most people in the U.S. have low levels of vitamin D.

With all the benefits vitamin D is thought to have, can it help your asthma? Here’s what you need to know.

What Is Asthma?

Asthma is a chronic disease that causes airways to become inflamed (swollen) and narrow, making it hard to breathe. There is no cure for asthma. People with asthma manage their disease by:

• Avoiding triggers
• Taking prescribed medicines to control and treat asthma
  
  

Common symptoms of asthma are coughing, shortness of breath, wheezing and chest tightness (or pain). Asthma may lead to a medical emergency. If symptoms do not improve after following your Asthma Action Plan, call your asthma care provider or 911 right away. If you do not have an Asthma Action Plan, ask your asthma care provider so you know what to do and when to call for help.

What Is Vitamin D?

Vitamin D is an important vitamin that helps your body absorb calcium. This is important for your bones and muscles. It also supports your nervous system and immune system. Vitamin D is often called the “sunshine vitamin.” Being out in the sun helps human skin make vitamin D. But many people do not get enough. People who do not get enough vitamin D through sunlight include:

• People with darker skin
• People who protect their skin from the sun when they are outside (clothing, shade, UV protection)
• Older adults and people who rarely go outside
• And people who live in certain locations (including much of the U.S.!)
  
  

You can also get vitamin D in the foods you eat or through supplements.

What Does Science Say About Vitamin D and Asthma?

Research shows an important relationship between low vitamin D and poor bone health. Scientists believe vitamin D may impact other areas of health.

Here is a recent analysis of multiple studies that look at the link between vitamin D and asthma:

In 2016, researchers found vitamin D is likely to reduce the risk of severe asthma attacks and health care use. But these findings were generally limited to only people with mild or moderate asthma. It also only looked at people with lower baseline vitamin D levels. Children and people with frequent severe asthma attacks were under-represented.¹

In 2023, researchers looked at more recent studies. They compared the results of 20 studies. Fifteen included 1,155 children and five trials included 1070 adults with mild to moderate asthma. They concluded that vitamin D is not likely to reduce the risk of asthma episodes or attacks or improve asthma control.²

The study did not include many people with very low vitamin D levels (below 25 nmol/L), so more research may be needed in this group.

What Does This Mean for People With Asthma?

It’s still unclear how vitamin D impacts asthma. But if your vitamin D levels are low, there are ways to build your levels back up for your general health:

• Take a vitamin D supplement
• Eat foods rich in vitamin D (examples include fortified foods, mushrooms, egg yolks, some fish, cod liver oil)
• Safe sun exposure (take care not to damage your skin or put yourself at risk of skin cancer)
  
  

Taking a vitamin D supplement is the most reliable way to keep up your vitamin D levels.

If you have asthma and low vitamin D levels, don’t rely on vitamin D supplements to help you manage your asthma. Vitamin D is NOT an asthma treatment and NEVER replaces your prescription medicine. It will not make your lungs function better or treat day-to-day asthma symptoms.

If you and your doctor decide you should take a vitamin D supplement, you must also take your prescribed asthma medicine. You should not take vitamin D with certain medicines, so talk to your doctor or pharmacist. Read package inserts to make sure there aren’t any interactions.

Is Vitamin D Safe?

Yes, vitamin D is safe in the appropriate dose for general health. The NIH gives a general guide for the recommended amounts of daily vitamin D. Ask your doctor about what amount is right for you and your health.

Medical Review: May 2023 by Neeta Ogden, MD

References
1. Martineau AR, Cates CJ, Urashima M, Jensen M, Griffiths AP, Nurmatov U, Sheikh A, Griffiths CJ. Vitamin D for the management of asthma. Cochrane Database of Systematic Reviews 2016, Issue 9. Art. No.: CD011511. DOI: 10.1002/14651858.CD011511.pub2. Accessed 08 May 2023.
2. Williamson A, Martineau AR, Sheikh A, Jolliffe D, Griffiths CJ. Vitamin D for the management of asthma. Cochrane Database of Systematic Reviews 2023, Issue 2. Art. No.: CD011511. DOI: 10.1002/14651858.CD011511.pub3. Accessed 08 May 2023.