A diet high in fiber triggers a chain reaction via the gut bacteria that protects against the inflammatory process involved in asthma, according to a recent study published in the journal Nature Medicine. Gut bacteria are known to ferment dietary fiber, a process that produces beneficial compounds, or metabolites. In the current study, the researchers found that the fermentation process in the gut produced fatty acid metabolites that entered the bloodstream and reduced the inflammation response to allergens in people with allergic asthma.

“We are now showing for the first time that the influence of gut bacteria extends much further, namely up to the lungs,” noted Benjamin Marsland, MD, lead researcher. Using an animal model, they fed mice a standard diet with a high amount of dietary fiber or a standard diet low in fiber, comparable to the standard American diet (SAD). They found that the fatty acids in the bloodstream influenced immune cells in such a way that, when the mice were exposed to dust mite allergens (a common allergen for people with asthma), the immune system mounted a weaker allergic response.

This study will lead to studies in humans to determine whether the same effects occur. In the meantime, keep your fiber intake high by eating plenty of non-starchy vegetables and low-sugar fruits. And take a fiber supplement to be sure that you reach your daily 35 grams of fiber.