For two weeks, lab mice ate one of three diets: low-fiber, or regular chow, or food supplemented with fiber-rich pectin. Then the mice were exposed to allergy-inducing dust mites. And the low-fiber rodents suffered from increased airway inflammation, while the high-fiber group experienced less of an asthmatic response.
Seems that fiber supports gut bacteria that produce anti-inflammatory molecules called short chain fatty acids. These molecules then enter the bloodstream, where they can influence the immune system. An over-reactive immune system can play a role in allergies and asthma. But the fatty acids can calm down the immune reaction. The work is published in Nature Medicine. [Aurélien Trompette et al., Gut microbiota metabolism of dietary fiber influences allergic airway disease and hematopoiesis]
Directly injecting the mice with a short chain fatty acid had a similar anti-inflammatory effect. But mice probably prefer fiber to a series of shots—and it still helps them breathe easy.
—Sophie Bushwick
[Scientific American is part of Nature Publishing Group.]
