What are food allergies and intolerances?
Foods cause adverse reactions that can be divided into two main groups: allergic reactions mediated by the immune system that recognizes as foreign something in principle harmless as a food, and non-allergic, non-immunological reactions, also identified as intolerances. The former, in turn, are divided depending on the mechanism by which they occur into reactions mediated by immunoglobulin Ig, which is what is popularly known as food allergy. Other immunological reactions not mediated by this immunoglobulin, fundamentally the most important which is the best known disease, Celiac disease, and other more infrequent entities such as esophagitis or eosinophilic gastroenteritis processes. In contrast to all these processes of immunological origin, we have the non-immunological, non-allergic processes, fundamentally associated with a metabolic cause, normally due to a deficit or malfunction of certain enzymes that cause an incorrect absorption of certain sugars. Fundamentally we have in this sense the lactose intolerances and fructose intolerances. There are other pictures of uncertain mechanism, especially problems of intolerance to seafood, particularly bivalves. And then, finally, there are some cases of pharmacological mechanism due to substances released directly by food or included in its own composition, such as Histamine. Each of these entities has a different diagnostic and therapeutic approach.
How can they be diagnosed?
First of all, the most important thing in the diagnosis of a food allergy or intolerance is a correct clinical history. Depending on the suspected history, the diagnostic workup will be different in each case. Food allergies are diagnosed mainly with skin tests, if necessary also allergy tests and in many patients the so-called provocation or exposure tests. Sometimes exclusion and controlled reintroduction diets are also useful. In patients with suspected celiac disease we have tests and, in many cases, it is necessary to refer to a gastroenterologist to make the diagnosis by means of an intestinal biopsy. The non-allergic pictures, of enzymatic mechanism are mainly made by means of determinations with exhaled air, breath tests, which are going to give us very precise and reliable information. I would like to warn that all these panels of analysis of supposed food intolerances do not have any type of diagnostic validation, they have no real clinical utility. No academy or scientific society, whether of allergology, digestive or endocrinology, endorses them anywhere in the world.
What does their treatment consist of?
The treatment in general in all allergy or intolerance processes, once we have obtained a correct diagnosis, is fundamentally the avoidance of the food that causes the clinical problem. Obviously this sometimes conditions very restricted diets where it is very important the proper support from specialists, collaborators in our group, nutritionists, who can advise which are the most appropriate personalized diets taking into account these restrictions. It is also very important to avoid food traces of those allergens, of those foods that can create clinical problems and in that sense it is important to detect which are the specific brands or manufacturers that we can use for certain allergic or intolerance processes. When we have already established the clinical problem, allergic reactions that can cause food can be adequately controlled with treatments with corticoid antihistamines and in some cases of severe reactions self-injectable adrenaline that the allergist will prescribe. In cases of intolerance, treatments with probiotics in lactose intolerance and even fructose intolerance can be of great clinical utility as a support to avoidance measures and exclusion diets.