The Role of Vitamin D in Asthma Care

In recent years, researchers have discovered a connection between vitamin D levels and asthma. Low levels of vitamin D have been linked to an increased risk of asthma attacks. This risk has been found in both children and adults with asthma.¹

Many people in the asthma community may wonder if increasing vitamin D intake could help reduce their risk of an asthma attack. Understanding the connection, as well as the risks and benefits of vitamin D, can help you make informed choices about your health.

What is vitamin D?

Vitamin D is a nutrient and building block your body needs to create and maintain healthy bones. Vitamin D helps the body absorb nutrients and amino acids like calcium, magnesium, and phosphate. It is crucial to bone health because the human body can only absorb calcium when vitamin D is present.²

Vitamin D also has anti-inflammatory and antioxidant properties that help many functions in the body. It can help boost the immune system, muscle function, and brain cell activity.²

How can it benefit people with asthma?

Multiple studies show that vitamin D can improve lung function in people with asthma. Because of this positive relationship, vitamin D may be a helpful supplemental therapy.³

Studies show vitamin D helps boost immune responses to viruses that trigger asthma attacks. It also decreases inflammatory responses.¹

Inflammation is the root of the problem in asthma. It makes the airways sensitive to triggers like allergens, mold, chemicals, and viruses. The airways react to these triggers by becoming narrow. In turn, this makes breathing difficult.⁴

Vitamin D in adults with asthma

Research shows that when taken with standard asthma medicines, a vitamin D supplement could reduce the risk of severe asthma attacks by 50 percent. In one study, a vitamin D supplement cut the risk of a severe asthma attack requiring hospital admission or an emergency room visit from about 6 percent to 3 percent. Vitamin D supplementation also reduced the rate of asthma attacks that needed steroid treatment.¹

Vitamin D in children with asthma

Evidence for vitamin D use in children with asthma is conflicting.

Research shows that having a mother who has asthma is a strong risk factor for her children also having the condition. In a study of pregnant women and their children, researchers found vitamin D taken throughout pregnancy notably reduced the rates of asthma in the children before their third birthday.⁵

However, the findings of a 2020 study on children with persistent asthma and low vitamin D levels did not support the use of vitamin D supplementation to prevent severe asthma attacks.⁶

Sources of vitamin D

Sunlight is the most common and efficient source of vitamin D. This is because our bodies make vitamin D from direct sunlight on the skin when we are outdoors.^2,7

However, our bodies do not make enough vitamin D from sunlight from late fall until early spring. This is when you may need to get vitamin D from other sources.^2,7

Vitamin D is not naturally found in many foods. You can get it from things like:^2,7

• Oily fish like salmon, sardines, and herring
• Red meat
• Liver
• Egg yolks
• Fortified foods like cereals, milk, and tofu

You can also get vitamin D from nutritional supplements. It is available in 2 forms: D2 and D3. Both forms increase vitamin D levels, but D3 often raises it higher and for longer periods than D2. Your body best absorbs vitamin D when it is taken with a meal or snack that includes some fat.⁷

Risks of vitamin D consumption

Generally, vitamin D is considered safe when taken in the right doses. The amount of vitamin D you need each day depends on your age. However, taking too much vitamin D can be harmful and cause side effects like:²

• Nausea and vomiting
• Constipation
• Weakness
• Confusion
• Heart rhythm problems
• Kidney stones

Vitamin D may interact with some medicines, including anticonvulsants, steroids, and stimulative laxatives.²

You cannot get too much vitamin D from sunlight. This is because your skin limits the amount of vitamin D it makes.²

Things to consider

Some reports show contrasting effects of vitamin D on asthma, while others say there is not enough evidence to make a positive link. Also, it is not yet clear whether vitamin D supplements can reduce the risk of severe asthma attacks in all people with asthma or if it only helps people who have low vitamin D levels.¹

While research does show vitamin D use helps prevent severe asthma attacks, data has not found that it helps improve everyday symptoms of asthma.¹

It is important to keep in mind that vitamin D should never replace the asthma drugs your doctor has prescribed for you. Before taking vitamin D supplements, talk to your doctor. Together, you can decide if they are right for you and your treatment plan.