It is called oral allergy syndrome (OAS) and is a specific condition that brings together a collection of different symptoms triggered mainly by pollen. How? When we eat certain foods, the body triggers an abnormal immune response. Eating a fruit or a peanut can cause swelling of the mouth and itching, for example. So how do you know if you are facing a simple allergic reaction to a food or to oral allergic syndrome? We talked about it with Professor Giorgio Walter Canonica, Head of the Center for Personalized Medicine, Asthma and Allergology in Humanitas.

The Role of Diet on Allergy

According to data from the American Academy of Allergy, 75% of patients allergic to birch pollen have problems ingesting celery and apples. But the problem, according to the experts, lies mainly in the diet, that is not balanced and too rich in fat. The Humanitas specialist also expressed his opinion on the subject: “The diet – explained Professor Canonica – can affect the probability of developing allergies, especially food allergies: it is no coincidence that these are much more frequent in the USA, while in Italy they are even less widespread, thanks to the spread of the Mediterranean diet”.

“It is very important to identify allergies as soon as possible, in order to give the right advice to the patients who have annoyances by eating certain foods but have never linked the problem to their allergy or that are not directly allergic or intolerant to that particular food”, said the Professor. These particular molecular tests (for example Isac, which investigates between 112 allergens and Alex, which controls 282) are not yet among the tests reimbursable by the National Health System.

“To detect the cross-allergies is necessary a molecular allergological diagnosis – added the doctor -: they are tests that sift dozens of molecules and allergens, identify those with which the patient reacts and identify all the cross-reactivity to which it is sensitive,” explained Canonica. “If for example the patient is allergic to tropomyosin, it is very likely that he will have discomforts eating crustaceans and snails.

Environmental factors

Cases of new allergy patients have increased over the years also due to climate change, temperatures and low rainfall that allow pollen to remain in the air for longer. “Added to this, of course, is pollution – concluded the specialist – which damages the respiratory mucous membranes”.