The main differences between food allergy and food intolerance

Dr. Pedro Gamboa Setien is a reference in the specialty of Allergology. He is a member of medical associations both in Spain and abroad, and has also been a speaker at international congresses. He also holds important positions in numerous journals outside our country.

What is the difference between allergy and food intolerance?

Well, they are two radically different processes. A person who has an intolerance, for example, the most typical, lactose intolerance, really what he lacks is a protein in the digestive tract and when he drinks milk with lactose or when he drinks yogurts or when he drinks some other product with milk he is not able to metabolize it, it accumulates in the digestive tract and he starts with abdominal pain, abdominal distension, a lot of gas, nausea, vomiting, but the problems never go beyond that. However, when a person has an allergy to milk, for example, the problem he has is that he has an immunological reaction, his body recognizes milk as something foreign and potentially dangerous and fights against it and it can give rise, from very mild symptoms such as minimal itching of the mouth or a slight swelling of the lips, to more intense symptoms such as abdominal pain, nausea, vomiting, may start with itching of the skin all over the body, to much more severe symptoms such as difficulty breathing, such as dizziness, loss of blood pressure, heart failure and in the most severe cases can compromise the patient’s life.

What happens in the body when an allergic reaction occurs?

When a person ingests a food to which he/she is allergic or small traces in food to which he/she is allergic, his/her body actually rejects, interprets this food as something that is harmful to him/her and reacts against it. What happens then depends on the person and the protein to which the food is allergic, for example, a person allergic to hazelnut in central Europe often those symptoms are limited only to itching in the mouth, because first they become allergic to birch pollen, birch pollen has a protein that is also in many nuts and many vegetables but with the advantage that when it reaches the stomach it is destroyed, or when food is cooked it is also destroyed, so the symptoms are limited only to the oral cavity. There are, however, others who are allergic, to peanuts for example, or to nuts.

For example, there are those in the Mediterranean who are sensitized to another protein, called lipid transfer protein, which is not destroyed either by heat or in the digestive tract, so it is absorbed and can cause more or less severe symptoms. Even others allergic to nuts more typical of the United States or Northern Europe are sensitized to other proteins within those nuts that are not destroyed either by cooking or roasting, or by ingesting them and can lead to very serious symptoms including anaphylaxis or death of the person. It depends both on the person, the type of protein within the food to which he/she is allergic and the resistance of that protein to be destroyed by heat or stomach juices.

What are the causes of a food allergy?

It depends fundamentally on the age. When we are talking about early childhood below the age of four, there are two foods that are the kings of food allergy in children: milk and egg, which are the first ones the child comes into contact with. Fortunately, in eighty percent of children this allergy is lost, they are able to overcome it by the age of four or six years, so that later in adulthood most of them can tolerate the intake of these foods. Then, as children get older, other food allergies such as fish, nuts, etc., develop. But when we are talking about older children in adolescence or adults in southern Europe, where we are, let’s say that the king of food allergy food is what is called the pinkish fruits, ie, the family of peach, cherry, plum, nectarine, Paraguayan, and so on. They are the most frequent cause of food allergy. Twenty percent of these people with allergy to pinkish fruits are also allergic to nuts.

Other foods in order of frequency that appear to cause food allergy, but already in adulthood, are: fish, much less frequently crustaceans, then, with relatively less frequency, crustaceans and mollusks, may be legumes, or kiwi which is a food that is also very often of food allergy in adults and also in children, but think that any food can be susceptible to cause a food allergy. I repeat, if we are talking about children we are mainly talking about milk and eggs, if we are talking about adults, we are talking more about pink allergies, nuts, fish and crustaceans.

Read Now 👉  Wasp and bee sting

How can we measure the symptoms? What tests are available to diagnose a food allergy?

The symptoms of food allergy vary greatly in intensity; from the mildest to the mildest that are limited only to the mouth with itching of the mouth, itchy throat or a slight swelling of the lips. If the symptoms are a little more intense, as soon as people eat the food, they start with snot, sneezing, itchy nose and eyes, and swollen eyes. The same as if they were allergic to pollen or mites, if the symptoms are a little more intense, then they start with digestive symptoms: stomach pains, nausea, vomiting, diarrhea. If they are even stronger, they may start with respiratory symptoms: difficulty in breathing, coughing, noises when breathing, skin symptoms may appear with hives, itching, the face may swell, even the throat may swell and the sensation of difficulty in breathing may increase. If the symptoms are even more severe it may appear as a drop in blood pressure, loss of consciousness and in very isolated cases, fortunately for patients but it can happen, it can even cause death in the patient.

How is a food allergy diagnosed? Well, once people tell us the symptoms they have had, we do the classic skin tests with drops of the different suspected foods on the forearm. A small puncture is made which is not painful and in those places where it coincides that we have applied the food to which the person is allergic will appear a welt or a slight itch and with that we know the foods to which people are allergic. In addition, blood tests are always done to measure what is called the IgE response, i.e. the protein formed by the allergic person to the food or foods to which he/she is allergic, and this will give us an idea of which foods, to what degree and what risk the person has to the food to which he/she has developed the allergy.

Who is more likely to develop a food allergy, children or adults?

The frequency of food allergy is somewhat higher in children because of milk and egg allergies that appear in this first age of life, but children have an advantage over adults and that is that, especially with these two foods, milk and egg, eighty percent of children are able to overcome this allergy and tolerate, when they are a little older, from the age of six, the intake of milk and egg. However, in adults they have the disadvantage that a food allergy that starts in adulthood is rarely overcome with age. In fact, there are some food allergies that are not overcome practically never, or in a very small percentage of cases, i.e., a child with nut allergy will overcome it in a very low percentage of cases, no more than twenty percent, in an adult practically never. There are also other types of allergies that are very difficult to overcome: allergy to crustaceans is also something that is more or less maintained throughout life. Allergy to fish may be that, in some cases, you can take some and in others not.

In any case, what we must insist to all people with food allergy is that at the slightest doubt that they may have a potentially serious reaction, please always carry adrenaline with you. Adrenaline auto-injectors are simple, easy-to-use devices that can be life-saving for people with food allergy. There are several models on the market, but this is one of them, which is extremely easy to use: simply loosen the cap, grip firmly and place it on the outer surface of the thigh. It is tightened on top of the pants, the skirt, the stockings, it goes through all these surfaces. It is squeezed and held tight for five, ten seconds and is usually able to maintain, in a more or less stable situation, patients long enough to be able to go to an emergency department where they would finish treating the allergic reaction.

In some patients, we recommend carrying not one, but two of these devices because if the first dose does not achieve a clear improvement, it can be repeated after five minutes, thus facilitating access to an emergency department. But the important thing is that both parents of allergic children and people with food allergy always carry these autoinjectors with them, especially when they eat away from home and the risk of small dietary transgressions increases, manipulations by restaurants in the handling of food or having what is called a hidden allergen that the food handlers have not been aware of and the patient can thus have a severe allergic reaction. It is between taking or not taking adrenaline and living or not living.