In a new analysis of allergy studies, Charles Mackay — an immunologist at Monash University in Melbourne — argues there is strong evidence that bacteria in the gut have the enzymes needed to digest dietary fiber, and when these bacteria break down fiber, they produce substances that help to prevent an allergic response to foods, the LiveScience Website reports.
 

Much of the research to date has been done in mice, and dietary factors are unlikely to be the sole explanation for why allergy rates are rising.  But the studies suggest that promoting the growth of good gut bacteria could be one way to protect against, and possibly even reverse, certain allergies.

About 15 million Americans have food allergies, which have increased by 50 percent since 1997, according to Food Allergy Research & Education, a nonprofit organization that advocates for people with food allergies.
 

About 90 percent of people with food allergies are allergic to peanuts, tree nuts, wheat, soy, eggs, milk, shellfish, and fish.
 

Mackay noted fiber promotes the growth of a class of bacteria called Clostridia, which break down fiber and are some of the biggest producers of byproducts called short-chain fatty acids. Past research shows that such fatty acids prevent gut cells from becoming too permeable, and letting food particles, bacteria, or other problematic compounds move into the blood.
 

"A leaky gut is bad because all these undesirable things go from the gut into the bloodstream, and they screw up the immune system," Mackay told Live Science.