Asthma and Diet: Here’s What You Should Know

Asthma is a chronic lung disease that can start at any age. It causes the lining of the bronchial tubes—the airways leading into your lungs—to become red, swollen, and sensitive. Once these airways are inflamed, they become hypersensitive to triggers that may not bother others. Under these circumstances, triggers can lead to an asthma attack: The airways’ lining further swells, the muscles that wrap around the bronchial tubes tighten or spasm, and more mucus than usual is produced, which can clog the airways. As a result, the airways become even narrower, making it harder to get air into the lungs.

GET OUR FREE 20-PAGE ULTIMATE PLANT-BASED BEGINNER'S GUIDE

Asthma-related inflammation can be present in the airways without any obvious symptoms. When this inflammation escalates during an asthma attack, symptoms can include shortness of breath, rapid breathing, chest tightness, coughing, or wheezing.

Asthma attacks can be triggered by different factors in different people. Common triggers include air pollution, tobacco smoke, dust mites, pets, mold, cleaning products, exercise, and strong emotions, according to the Centers for Disease Control.

When not properly managed, asthma can be dangerous and potentially fatal. According to the most recent numbers from the World Health Organization, asthma caused 461,000 deaths worldwide in 2019. Avoiding triggers and using medications are the primary interventions for managing asthma. Researchers are investigating healthy lifestyle behaviors, including diet, that may help prevent or manage asthma, lower morbidity and mortality, and improve quality of life. 

There is rising interest in the impact of diet on an asthma patient’s condition. “While lifestyle medicine in pulmonary disease is in its infancy, evidence-based practice and lessons learned from lifestyle interventions in other chronic diseases, such as diabetes and atherothrombotic vascular disease, should impart critical insights for lifestyle interventions in asthma,” says Sharmilee Nyenhui, MD, a researcher from the University of Illinois at Chicago’s Division of Pulmonary, Critical Care, Sleep and Allergy, who recently co-authored a commentary on the subject.

Existing evidence points to some clear patterns.

Global rates of asthma began steadily rising in the 1980s with the spread of the Westernized diet (aka the Standard American Diet), characterized by highly processed convenience foods, fried foods, refined grains, sweets, processed and red meats, and high-fat dairy products, with low intake of fruits, vegetables, and whole grains. 

In 2015, researchers from Harvard surveyed the eating patterns and asthma rates of children in Puerto Rico. They found that a dietary pattern including frequent consumption of dairy products and sweets, sodas, and snacks, with infrequent intake of vegetables or grains, led to increased odds of asthma in the children. 

Fast food, a hallmark of the Westernized diet, has also been implicated in asthma. The International Study of Asthma and Allergies in Childhood, a large-scale epidemiological study, leveraged data on the dietary habits of a half million children and adolescents from around the world. Those who consumed fast food three or more times per week had an increased risk of severe asthma, according to the results.

A systematic review by the European Academy of Allergy and Clinical Immunology Lifestyle and Asthma Task Force concluded that the existing evidence supports recommendations in clinical practice to increase the intake of fruits and vegetables as a way of reducing the risk of asthma, particularly in children.

In the Harvard study of Puerto Rican children, the children with a healthy diet (defined in the study as frequent consumption of vegetables or grains and infrequent consumption of dairy products and sweets) had, on average, 83 percent lower odds of asthma than children eating an unhealthy diet. The researchers found that a healthier diet was associated with lower inflammatory cytokine levels. 

Fruits and vegetables—and other plant foods such as whole grains, seeds, nuts, and legumes—are high in antioxidants, which protect against inflammation. They also are rich in fiber. When you consume fiber, your gut microbes produce short-chain fatty acids that reduce inflammation, such as butyrate. “Plant-based foods support the biodiversity of the gut microbiome and also promote the bacteria that are anti-inflammatory,” says Kahleova of the Physicians Committee for Responsible Medicine. 

In a study of asthmatic adults conducted by Wood’s team in Australia, patients were assigned for two weeks to diets with varying levels of antioxidants: one group ate a high-antioxidant diet with five servings of vegetables and two servings of fruit daily; a second group ate a low-antioxidant diet with two or fewer servings of vegetables and one serving of fruit daily. After the two weeks were up, researchers continued to monitor the subjects for three months. They found that the high-antioxidant group, on average, went significantly longer without experiencing an asthma attack. The low-antioxidant diet group was more than twice as likely to have an asthma attack. 

Anecdotally, Forks Over Knives has heard from people who have had success in controlling their asthma after adopting a whole-food, plant-based diet:

Experts continue to research just how much of an effect diet has on asthma, with the goal of someday developing standardized dietary guidelines. The available research shows that eating a plant-predominant diet rich in fruits, vegetables, whole grains, and other fiber-rich foods can help mitigate asthma by contributing to a healthy weight, balancing a healthy gut environment, and protecting against systemic and airway inflammation. 

“The best dietary strategy for asthma is to consume a diet high in fruits and vegetables and low in fast foods, whilst achieving and maintaining a healthy weight,” says Wood. “This strategy will protect against inflammation, which is the underlying cause of asthma.”

Ready to get started? Check out Forks Meal Planner, FOK’s easy weekly meal-planning tool to keep you on a healthy plant-based path. To learn more about a whole-food, plant-based diet, visit our Plant-Based Primer.