Food allergy is now a major public health issue, due to its increasing incidence over the past 20 years, particularly in western countries. Recently, alterations in gut microflora composition have been suggested as an explanation for developing food alergies. This is evident in germ-free mice, which tend to develop more-severe allergies, and given that specific probiotic treatment can alleviate food allergy symptoms.

Diet, especially consumption of dietary fiber, appears to be a critical determinant for gut bacterial ecology, diversity, and function. Dietary-fiber-derived metabolites have been implicated in gut health. Dietary fiber is fermented in the colon by anaerobic bacteria into short-chain fatty acids (SCFAs), mainly acetate, butyrate, and propionate to create a healthy gut. Western diets, typically high in fat but also low in fiber, may therefore be associated with changes in gut bacterial ecology and this may compromise oral tolerance and allow for the development of food allergies.
We all should be eating more wholesome, whole foods with lots and lots of fiber and avoid poisons like preservatives and antibacterials which kill the gut bacteria.