Vomiting, respiratory problems, skin outbreaks... Maybe the problem is indigestion, contact with a certain plant or flower or a skin ailment that is beginning to emerge. But is also possible that food is triggering such problems.

Allergies and food intolerences appear without warning and often without the affected person establishing a direct link between the symptoms and having eaten a certain food. Only after suffering several reactions does the person put two and two together and understand that it was, say, tuna, or a glass of milk, that is causing the trouble.

The body speaks
A food allergy is an extreme reaction by the immune system to a substance that is normally harmless and unleashes a release of histamine. The body views this substance as an enemy and generates anti-bodies to do away with it. Then, the body speaks. It shows symptoms in the intestines and stomach, difficulty breathing, swelling in the throat, mouth or lips, eczema, rashes and even palpitations of the heart. These problems can appear in pairs, in threes or separately and with varying degrees of severity. Just a taste of the food that causes them is enough. Sometimes all it takes is to touch or smell this food.

Allergy or intolerance?
The first distinction to be made is that between food allergy and food intolerance, which are similar ailments but have different origins. In the first case it is the body�s defenses that are at work. In the second, the problem arises when the food enters the digestive tract, which rejects it. Thus, food intolerence manifests itself with vomiting and diarrhea, and has no relation with the immune system.

One of the most common forms of intolerence is that involving dairy products, while there are many kinds of allergy _ also to milk and dairy products, fish, shellfish, nuts and eggs.

In theory any kind of food can cause a reaction. Keep in mind that what causes the allergy is not the food itself but the things it is made of, such as certain proteins. For this very reason many of them only cause reactions when eaten raw. When cooked or heated, the proteins are transformed and rendered harmless.

Treatment and prevention
Incidence of food allergies is relatively low: an estimated 2% of adults, although the figure goes up to 5 to 7% among children. As is the case with reactions to pollen and other substances, those stemming from food evolve and change so much they can even disappear, especially among children as they grow older. And, as with other health woes, there is a hereditary factor: a child of a mother or father with this problem has double the probability of suffering from it.

Diagnosing a food allergy starts with the first cases of reactions. Then, a study is done on family history and how foods eaten link up with the appearance of symptoms. Skin tests are carried out. Suspect foods are removed from the person�s diet and blood samples are used to study how the body�s defenses react to the substances that make up those foods. It is essential to narrow down the suspicious foods as much as possible. Otherwise, the tests would have to target everything in the person�s diet.

As for prevention and treatment, there is no solution other than identifying the allergen and removing it from the diet. There are no drugs that do away with the problem � only treatments that ease the symptoms and make the patient feel better after the allergic reaction has started.