3 Vitamins That May Impact Your Asthma

Some scientists believe that asthma and vitamin deficiencies are linked. It is thought that certain vitamins—most specifically vitamin D, vitamin C, and vitamin E—play a role in not only the development of asthma but also the severity and frequency of asthma attacks.

The link, though, between asthma and vitamin deficiencies—and whether vitamin supplements have any impact on the risk or severity of this common inflammatory airway disease—is still hypothetical. Vitamins can, though, help bolster the immune system and reduce infections that may trigger an asthma attack.

How Asthma and Vitamin Deficiencies Are Linked

The link between asthma and vitamin deficiency is largely hypothetical. The hypothesis is based on the long-held assumption that asthma is more common in countries that consume a Western diet (rich in refined sugar, fats, and processed foods) than those that rely on real foods (like fruits, vegetables, and whole grains).

In turn, because a Western diet is linked to an increased risk of vitamin deficiencies, many experts have jumped to the conclusion that vitamin deficiencies are the central link to asthma.

The current evidence does not support the theory. According to a 2015 review of studies published in the Annals of Allergy, Asthma & Immunology, there is no clear association between the Western diet and the rate of asthma in adults.

With that said, the researchers concluded that there may be a link between a Western diet and the severity and frequency of asthma symptoms. Whether this is due to vitamin deficiencies alone is unknown and further research is needed.

Furthermore, a 2024 study indicates that a Western diet is high in omega-6 fatty acids (too much of which can cause inflammation), low in fruits, vegetables, and whole grains (which are needed for antioxidants), and may lend itself to obesity. All of these factors may have adverse effects on asthma.

Vitamin D

Vitamin D is a fat-soluble vitamin that is produced in the skin following exposure to the sun. It is also found in dairy and other food products. Vitamin D is essential to bone health (as it helps the body absorb calcium) and also helps strengthen the immune response.

Foods that are rich sources of vitamin D include:

• Salmon
• Mackerel
• Mushrooms
• Milk (which is usually fortified with vitamin D)
• Yogurt
• Cheese

Numerous studies have suggested a link between vitamin D and allergic diseases including asthma, although the quality of the studies is generally poor.

A 2017 review of studies published in Cureus suggested that vitamin D can be effective as a complementary therapy for people with asthma. What the researchers could not say is how vitamin D is meant to influence asthma symptoms.

Similarly, a 2017 review in Clinical Therapy reported that low levels of vitamin D correspond to a higher rate of asthma attacks. Even so, there was no evidence that vitamin D supplements could either prevent or treat asthma.

A 2024 review, though, does explain that regular vitamin D supplementation (as an immune booster) reduces the incidence of respiratory infections, which can cause and worsen asthma attacks.

Like any dietary supplement, patients should speak to a medical provider about dosage, as taking too much vitamin D can cause nausea, vomiting, constipation, excessive thirst, frequent urination, and kidney stones.

Vitamin C

Vitamin C is a water-soluble vitamin found in many fruits and vegetables, especially citrus fruits. It is touted as a defense against the common cold.

Among the richest food sources of vitamin C are:

• Bell peppers
• Broccoli
• Lemons
• Oranges
• Strawberries
• Tomatoes
• Green leafy vegetables

Vitamin C also has antioxidant properties that may benefit people with asthma. Antioxidants are substances that neutralize oxygen-containing molecules called free radicals that cause long-term damage to cells.

It is thought that by reducing oxidative stress in the lungs, airway hypersensitivity—a central feature of asthma—may be reduced.

To date, though, there is little evidence to support the claim. While some studies suggest that vitamin C supplementation may reduce bronchoconstriction (the narrowing of the airways) following extreme exertion, there is no real evidence that it can either prevent or treat airway hypersensitivity and exercise-induced asthma or any other form of asthma.

Too much vitamin C can also lead to nausea, diarrhea, and kidney stones.

Vitamin E

Vitamin E is a fat-soluble vitamin found in nuts, seeds, oils, and green leafy vegetables. Vitamin E is important to the health and function of your eyes, brain, skin, and reproductive organs.

The best food sources of vitamin E include:

• Avocado
• Almonds and other nuts
• Broccoli
• Fish
• Olive oil
• Shellfish, like shrimp
• Spinach
• Sunflower seeds and other seeds
• Tofu

Like vitamin C, vitamin E has antioxidant effects that may benefit people with asthma. Even so, most of the evidence linking asthma and vitamin E is weak.

A 2013 review published in the American Journal of Respiratory and Critical Care Medicine could not find solid evidence that vitamin E had any effect on either severity, frequency, or prevention of asthma attacks.

However, there is evidence that high doses of tocopherol, a major form of vitamin E, may impair lung function and increase airway hypersensitivity (and therefore asthma attacks) in people with allergic asthma. Vitamin E supplements can also cause excessive bleeding if overused.

The Verdict

While vitamin deficiencies are commonly noted in people with asthma, there is no evidence that they “cause” asthma. More often, vitamin deficiencies are an indication of poor health that can increase a person’s susceptibility to infections, allergies, and other common triggers of asthma.

A 2017 review in Expert Review of Respiratory Medicine concluded that, based on the current research, “There is not enough evidence to support the usefulness of vitamin C, E, or D to reduce asthma exacerbations (attacks).”

That is not to suggest that vitamin supplements have no benefits. Many vitamins can reduce the risk of viral respiratory infections, like the common cold, that can trigger an asthma attack. That is no small feat given that 44% of all asthma attacks are believed to be associated with a viral respiratory infection.

If you decide to use vitamin supplements for any reason, understand that taking high doses poses certain health risks. Speak with a healthcare provider before using any supplement to boost the immune system or for any reason to ensure that it doesn’t interact with any medications you are taking. As a general rule, never exceed the dose on the product label. More is not necessarily better.

Summary

Vitamin deficiencies are common in people with asthma. There are some experts who believe that such deficiencies are linked to an increased risk of asthma. Others contend that vitamin supplements can help reduce the frequency or severity of asthma attacks. The deficiencies most often cited are vitamins C, vitamin D, and vitamin E.

To date, though, there is no strong evidence that vitamins can either prevent or treat asthma, although they can contribute to overall health. On the contrary, the overuse of tocopherol, a major form of vitamin E, may increase the risk of an attack in people with allergic asthma.