3 Vitamins That May Impact Your Asthma

Some scientists believe that asthma and vitamin deficiency are integrally linked. Researchers have looked into the role that certain vitamins—like vitamin D, vitamin C, and vitamin E—play in the occurrence and severity of the disease. While it is clear that diet does influence the incidence and prevalence of asthma, what is less clear is whether vitamin supplementation can prevent asthma or improve its symptoms.

Asthma Rates and Vitamin Deficiencies

The hypothesis is based in large part on higher rates of asthma in Western countries where diets rich in refined sugar, fats, and processed foods have led to widespread deficiencies of certain vitamins, including vitamin D and B complex vitamins.

By comparison, the rate of asthma in non-industrialized parts of the world that rely on real foods, including fruits, vegetables, and whole grains is generally lower. Although nutritional deficiencies are common in developing countries, those deficiencies are driven more by malnutrition than by the dietary habits of the population.

Vitamin D

Vitamin D is a fat-soluble vitamin found in dairy and other food products that is essential to bone health. It also helps strengthen the adaptive immune response, the part of the immune system meant to identify specific disease-causing microorganisms, some of which— like respiratory viruses—trigger asthma attacks.

Numerous studies have suggested a relationship between vitamin D and asthma.

A 2017 review of studies published in the journal Cureus concluded that a daily 500-IU dose of vitamin D may reduce the severity and frequency of asthma attacks in children. Doing so doesn't necessarily affect asthma but rather reduces the risk of common respiratory infections that trigger acute attacks.

Other studies have suggested that vitamin D may prevent the development of childhood asthma, although the evidence supporting these claims is generally weak and circumstantial.

A 2017 review of studies published in Clinical Therapy reported that, while low levels of vitamin D correlate to higher rates of asthma attacks, the findings do not support the benefits of vitamin D supplementation as a direct means of preventing or treating asthma.

It is more likely that vitamin D deficiency is an indication of a larger nutritional deficiency that will invariably affect the body's immune response and, in turn, its vulnerability to asthma attacks.

Vitamin C

Vitamin C is a water-soluble vitamin found in many fruits and vegetables, most especially citrus fruits. It is touted as a defense against the common cold and free radicals that cause long-term harm to cells of the body.

Vitamin C has anti-inflammatory and antioxidant properties that may benefit people with asthma. It has been proposed that vitamin C can reduce the oxidative stress placed on airway tissues which, in turn, may reduce their hypersensitivity to common asthma triggers.

Vitamin C may also reduce inflammation and hypersensitivity in the same way inhaled steroids used in asthma therapy do.

To date, however, the evidence supporting these claims is weak. While studies have shown that vitamin C can reduce bronchoconstriction (narrowing of the airways) following extreme exertion—suggesting that it may benefit people with exercise-induced asthma—there is little proof that it can either prevent or treat asthma in the larger population.

However, there is evidence that a daily vitamin C supplement may reduce the risk of viral respiratory infections in people at high risk of asthma attacks.

Vitamin E

Vitamin E is a fat-soluble vitamin found in nuts, seeds, oils, and green leafy vegetables. Many people take vitamin E supplements as a preventive measure to reduce the risk of a wide range of disorders, including heart disease, cancer, and Parkinson’s disease.

Like vitamin C, vitamin E has anti-inflammatory and antioxidant effects that may benefit people with asthma. Most of the evidence is based on studies that show a direct correlation between vitamin E deficiency and asthma severity.

A 2013 review in the American Journal of Respiratory and Critical Care Medicine suggested that the use of vitamin-E-fortified baby formula may reduce the incidence of childhood asthma, while also suggesting the vitamin E deficiency in mothers may increase the risk of asthma in a child up until the age of 5.

Despite these findings, the authors conceded that studies of vitamin E in asthma are inconsistent and that supplementation generally has little impact on lung function, lung capacity, asthma symptoms, or the frequency of bronchodilator use.

There is some evidence that high levels of tocopherol, a major form of vitamin E, may actually reduce lung function and increase airway hyperresponsiveness in people with allergic asthma.

Should You Supplement?

Most Americans get vitamin D through fortified foods and supplements, as typical Western diets do not contain enough to meet dietary needs. Most people eating a healthy diet will get enough vitamin C and vitamin E without supplementation.

Only your doctor can determine, through blood tests, if you are deficient in these or any other vitamins. Note, however, that vitamin E deficiency is considered rare in the United States.

While vitamin deficiencies in general are commonly noted in people with asthma, it would be inappropriate to regard them as the "cause" of asthma. More often, they are markers for poor health and nutrition that can invariably impact a person's susceptibility to infections, allergens, and other common triggers of asthma.

With respect to vitamin D, C, and E specifically, a 2017 analysis in Expert Review of Respiratory Medicine concluded that "there is not enough evidence to support the usefulness of vitamin C, E, or D... to reduce asthma exacerbations."

The benefits of supplementing for asthma, from the broadest perspective, appear weak, but that does not mean they are non-existent.

Certainly, any vitamin that can reduce the risk of viral respiratory infections, including the common cold, will reduce the likelihood of virus-induced attacks. And this is no small feat given that 44% of all asthma attacks are believed to be associated with a viral respiratory infection.

Dosing Cautions

There is no guidance as to which vitamin or dose is needed to protect people with asthma. But if you do decide to supplement, know that taking too much of some supplements can pose certain risks.

Taking excessive doses of vitamin D in an effort to treat asthma is unadvised. Doing so is more likely to cause vitamin D toxicity, characterized by nausea, vomiting, constipation, excessive thirst and urination, and the development of kidney stones.

The overuse of vitamin C should be avoided as it can lead to nausea, diarrhea, and kidney stones, particularly at doses exceeding 2,000 milligrams (mg) per day.

And although vitamin E supplements are generally considered safe, if overused, they may cause excessive bleeding, fatigue, nausea, blurred vision, and sexual dysfunction, particularly at doses exceeding 1,000 IU per day.

Dietary Recommendations

Most health authorities, including the National Institutes of Health (NIH), simply recommend that you meet your daily requirements with foods and, if needed, with dietary supplements.

Supplements should never be used as a substitute for a proper, balanced diet.

Foods especially rich in vitamin D include:

  • Salmon
  • Mackerel
  • Mushrooms
  • Milk
  • Yogurt
  • Cheese

Among the richest food sources of vitamin C are:

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

Among the best food sources of vitamin E are:

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