Helicobacter pylori as a protective factor against food allergy.

There is some evidence that Helicobacter pylori (Hp) infection may protect against asthma and allergy. The aim of the present study was to analyse the prevalence of Hp infection in adults with proven food allergy and to compare it with that in appropriate healthy controls. In addition, the effects of infection with Hp on urinary excretion of N-tele-methylhistamine and production of IgE and allergy mediators such as eosinophilic cationic protein (ECP) and mast cell tryptase, were assessed. Hp infection, the production of IgE and several allergy mediators and mucosal expression of interleukin-4 were measured in 42 patients with food allergy and compared with those in 20 healthy subjects. The prevalence of Hp infection among adult food allergy patients was 33.3% and it was significantly lower than that in the control group (40%). The excretion of urinary N-tele-methylhistamine was higher in food allergy patients than in healthy controls. In food allergy patients with Hp infection, the serum ECP was significantly lower than in food allergy patients without Hp infection. The serum IgE level was significantly higher in food allergy patients infected with Hp than in food allergy patients without Hp infection. We conclude that: 1) Hp infection is associated with a decreased risk for food allergy; 2) presence of Hp in food allergy patients has ameliorating effect on the production of allergy mediators such as ECP and mast cell tryptase and 3) Hp infection appears to be a protective factor against food allergy.