Dietary Fibers Fight Asthma: Another Reason to Eat Your Fruits and Vegetables

Unlike many major diseases such as malaria, AIDS, and tuberculosis, asthma is more prevalent in the United States and other developed countries than it is in less developed countries. There are different theories as to why. For example, the Hygiene Hypothesis states “excessive cleanliness interrupts the normal development of the immune system” leading to an increase in allergies and allergic diseases such as asthma. If this is true, it means our good hygiene is actually causing some of our health problems, although it’s still a better deal than malaria.

But recently, researchers at the Swiss National Science Foundation have discovered an alternate or additional explanation for why asthma is on the rise in the States-- our terrible diets.

It’s long been known that fruits and vegetables are good for you. Turns out, they may even simple things. How? First, the dietary fibers in fruits and vegetables are fermented in your intestines and turned into short-chain fatty acids. Then the acids enter your blood stream where they influence the development of immune cells, quieting immune system over-activity and reducing inflammation.

Or at least that’s how it works for mice. The researchers tested the effects of dietary fibers on asthma by feeding one group of mice a standard diet with 4% fiber and another group of mice a “Western” diet with just 0.3% fiber. Then they exposed both groups to dust mites, a common asthma trigger. The mice on the low-fiber diet had a much stronger, more mucusy reaction than the mice on the standard diet.

The scientists still need to do more tests before they can confirm that it works the same for humans. But the “examined aspects of the immune system[s] are virtually indistinguishable in mice and humans” so there’s a good chance it will. Either way, a healthy portion of fruits and vegetables is good for any diet.