The researchers fed some of the mice a high-fiber diet rich in vitamin A - found in many fruits and vegetables - while others were fed a diet with average fiber, sugar, and calorie content (the controls).
the researchers found that the high-fiber diet altered the gut bacteria of mice, which protected them against allergic reactions to peanuts.
Next, the researchers took some altered gut bacteria from mice fed the high-fiber diet and transferred it to the guts of mice with a peanut allergy that were "germ-free" - that is, they had no gut microbes.
Even though these germ-free mice were not fed a high-fiber diet, the team found that the addition of the altered gut bacteria protected them against allergic reactions to peanuts.
The researchers explain that gut bacteria break down dietary fiber into short-chain fatty acids.
In their study, the team found that increased levels of these fatty acids work with the body's immune system, preventing dendritic cells - which regulate food allergies - from triggering an allergic response. Vitamin A is also important for dendritic cell regulation.
Their findings were supported when the team gave the allergic mice water enriched with short-chain fatty acids for 3 weeks, before exposing them to peanuts. Their allergic response was reduced.
Overall, the researchers say their findings indicate that a diet low in fiber could be driving food allergies, and that adopting a high-fiber diet - enriched with vitamin A - could be way to lower food allergy risk.