For the 25 million Americans living with asthma, adopting a different diet could have a significant impact on the symptoms. “Many people — both patients and health professionals — don’t make a connection between what you eat and your lungs,” says Lisa Wood, PhD, professor of medicine and head of nutrition research at Hunter Medical Research Institute in Australia.
However, new research in the journal Immunity found a ketogenic diet (low in carbs and high in fat) was associated with lower levels of airway inflammation. Other research also shows a Mediterranean diet could have a similar effect.
Researchers suspect eating fewer carbohydrates and consuming more fat might help improve the function of cells that repair damaged mucous membranes, helping prevent asthma attacks. Still, “more research is needed to determine exactly which components of the dietary change are responsible for the effect,” notes study co-author Christoph Wilhelm, PhD, a professor at the University of Bonn.
In contrast, other research published in the journal Nature found high-fat diets exacerbated airway inflammation and were associated with more asthma attacks. Mice fed a high-fat diet for two weeks showed increased airway hyperresponsiveness or the tendency for the airways to narrow, making it harder to breathe.
Moreover, in previous research in the journal Nutrients, Wood found a Western diet (which includes a lot of refined grains, red meats and sugar-laden sweets) triggered inflammation — and the effects happened fast. Just four hours after eating fast food, people with asthma showed increased airway inflammation and the medication in their inhalers didn’t work as well. Wood attributes the link to the high calorie, high-fat content in fast food.
The type of fat may play an important role. Multiple studies show strong links between a Mediterranean diet and reduced airway inflammation among those with asthma. Unlike a Western diet, which includes lots of saturated fat, the Mediterranean diet focuses on healthy omega-3’s (from sources like fatty fish), which have been shown to reduce inflammation. One study showed eating two servings of fatty fish per week reduced airway inflammation and lowered the need for asthma therapies like inhalers.
In another study, Wood found a high intake of fruits and vegetables (hallmarks of a Mediterranean diet) was associated with less mucous and reduced inflammation. “When people consumed a high fruit and vegetable diet — more than seven servings per day — for three months, their risk of having an asthma flare-up was halved [compared to people eating fewer servings of fruits and vegetables],” says Wood.
The effect might be about more than just nutrients. “There is evidence that obesity can make asthma harder to control,” says Lorene Alba, certified asthma educator and director of education for the Asthma and Allergy Foundation of America. “A healthy diet that helps keep your weight in check could also ease your asthma symptoms.”
Alba also suggests steering clear of foods that are high in sulfites such as hot dogs, deli meat, shrimp and wine, which are known asthma triggers. “Identifying and reducing your exposure to the things that trigger your asthma, including food, plays a key role in getting asthma well controlled,” she says.
Consider tracking your food with an app like MyFitnessPal to identify personal triggers. “Log the foods you eat (and drink), note your asthma symptoms and look for patterns,” recommends Alba. “If you can correlate symptoms with what you eat, you can focus on a diet that helps you feel your best.”