Why are food allergies becoming so common? The hygiene hypothesis has been around for a while, linking extra-clean households with allergies. A recent study offers a possible reason: Pesticides and chlorine may kill the naturally occurring "good" bacteria in humans’ digestive systems, causing food allergies.
Antibiotics were previously linked in the same way. We need certain bacteria in our guts in order to digest food properly. Killing of the bacteria that live inside us may be hazardous to our health.