Although an intolerance to a substance can trigger symptoms quite similar to those of an allergy, the immune system is not involved in these reactions. Intolerance results from an inability to properly digest a food or one of its components due to the absence or inactivity of certain enzymes. Symptoms are usually only digestive, causing gas, diarrhea and stomach pain.

In the case of an allergic reaction, the immune system, through the release of IgE, defends itself excessively against a normally harmless substance, with all the symptoms already mentioned: rhinitis, asthma, conjunctivitis... which can lead to anaphylactic shock.

Allergenic substances are also present on our plates. While some foods are indeed allergenic, dyes, preservatives and other added elements cause, except in rare cases, simple intolerances.

Since July 1, 2015, following Decree No. 2015-447 of April 17, 2015, consumers must be informed of the presence of allergens responsible for over 90% of food allergies. On pre-packaged foods, these substances must appear on the label. For unpackaged food, the information should be prominently displayed near the product. As for canteens and restaurants, they must keep an updated list of potential allergens that must be made available to customers upon request.

The list of allergens that must be mentioned includes the 14 major food allergens. Cereals containing gluten: wheat, rye, barley, oats, spelt, kamut or their hybridized strains. There are, unfortunately, some exclusions. Thus, glucose syrups made from wheat or barley, maltodextrins made from wheat, and cereals used in the manufacture of ethyl alcohol of agricultural origin should not be indicated. The crustaceans, eggs, fish, arachids, soy, milk, and dairy products (including lactose), nuts, celery, mustard, sesame seeds, lupine, mollusks. The sulfites must also be listed on the products. However, if they are present in the product in amounts less than 10mg/kg or 10ml/litre, they may not be indicated on the label.

Beware, however: this labelling rule is only valid for ingredients voluntarily introduced into the recipe by the manufacturer. Allergens that may be present due to contamination of other foods, for example during transport or preparation, are not necessarily indicated. If some professionals announce them with phrases such as "may contain traces of..." or "manufactured in a workshop that uses...", not all do so, because none of them is required, legislatively speaking, to do so.

To avoid unpleasant surprises, consider eating organic food that you prepare yourself.

The main symptoms of a food allergy can be digestive (gastric reflux, nausea, diarrhea, even vomiting), cutaneous (hives, rash, angioedema), or respiratory (asthma, rhinitis, coughing, difficulty breathing). Palpitations, tingling in the throat and tongue and a drop in blood pressure may also occur.

In the most severe case, the allergy can result in life-threatening anaphylactic shock.