Beneficial bacteria in kefir block the antibody that activates histamine, a chemical that triggers allergic responses such as inflammation and difficulty breathing. Kefir also appears to prevent allergy-inducing food antigens from passing through the intestine into the blood.

Up to 8 percent of young children suffer from food allergies. Kefir could be used to help prevent these allergies, and the bacteria and compounds in it could be used to produce medicines.

From: http://news.sympatico.msn.ca/Kefir+fixes+food+allergies/ScienceandTech/