Know what you're eating

Food allergies

Food allergies

Around the world, there are almost 520 million people who may have a food allergy. According to figures provided by the World Allergy Organization, no country has reported a fall in food allergies in the past 10 years.

In Europe there are over 17 million people who have a food allergy. Of these, 3.5 million are under 25 years of age.

The most significant increase is seen in children and young people, especially in terms of the number of potentially fatal allergic reactions in children.

Across Europe, food allergies are the main cause of anaphylaxis in children aged 0 to 14 years.

According to current hospital figures, the number of hospital admissions due to severe allergic reactions in children has increased sevenfold in the past 10 years.

In the case of Spain, there are two million patients who suffer some sort of food allergy, specifically around 8% of under-14s and 2-3% of adults.

What is a food allergy?

A food allergy is an exaggerated response by the immune system after it identifies certain proteins from other living things as harmful, causing inflammatory reactions that mainly affect the respiratory system and which can cause severe problems.

The severity of an allergic reaction will vary from person to person. Whereas one person may need to be taken to an emergency room immediately, another may only have an itchy mouth.

The reaction can take place within minutes or after a few hours.

In turn, food can also cause an allergic reaction after exposure to it through the respiratory system, causing asthma or rhinitis.

Foods that cause allergic reactions are called food allergens. There are over 120 foods that are said to cause food allergies. Just under a dozen statistically tend to cause most of the reactions:

  • Milk
  • Eggs
  • Seafood
  • Nuts
  • Wheat
  • Legumes
  • Soya
  • Fruits
  • Fish


Food allergies appear when there is a failure in the tolerance of the immune system due to several possible factors:

  • People’s genetics
  • The state of the intestinal mucosal barrier
  • Age
  • The amount and form of presentation of the food

When the person with an allergy ingests the food causing the reaction, the allergen binds to the IgE on the surface of the basophils and mastocytes. It then activates them, which leads to the release of the histamine and other inflammatory substances responsible for the allergic reactions.

Symptoms vary not only in nature, but also in intensity.

The time it takes for them to appear is another factor that depends on the person. It can occur just a few minutes after ingesting a specific food product or hours later.


The most common symptoms, listed from mild to moderately severe, include:

  • Itchiness and redness anywhere on the skin
  • The appearance of hives
  • Rashes
  • Itchy mouth and ear canal
  • Sickness and vomiting
  • Stomach pain
  • Diarrhoea
  • Nasal congestion or discharge
  • Dry cough, sneezing and a strange taste in the mouth

The most severe symptoms are:

  • Swelling and dryness of the lips, tongue and throat. When this occurs, the allergic person could suffer serious difficulties in swallowing solids or liquids. Throat inflammation can be so severe that it can even obstruct or completely block the airways.
  • A decrease in blood pressure that can, in turn, cause dizziness, confusion, weakness or fainting.
  • Pain in the chest or a weakened pulse.
  • Anaphylactic shock. This happens when several of the mentioned disorders are accompanied by tachycardia and a sudden increase in the pulse, which then drops to below normal speed. If it is not treated quickly the patient will end up falling unconscious. All these issues are a reflection of what is happening inside the body: blood vessels are dilating; tissues are filling up with liquid and the organs are not receiving enough blood.

Differences between an allergy, inflammation and intolerance

Many people mistake these three conditions or use the terms “allergy”, “intolerance” and “inflammation” interchangeably to describe their problem, as if they were synonymous, when in reality they have different meanings.

The main difference is in their origin, as they have different causes and symptoms.

Food allergy

In general, the first contact between a substance and the immune system is used to recognise and classify it. If the body decides that it is hostile material, it will attack it the next time it comes into contact with it.

When the confrontation takes place, the body acts quickly in the face of what it perceives as an imminent threat. In mere minutes, white blood cells create antibodies that surround the food to neutralise it.

Histamine is then released, a proinflammatory chemical substance that causes allergic reactions.

Food inflammation

The immune system is also involved in the disorder known as inflammation, but in this case it is not an immediate reaction that appears upon first contact with the food in question.

The patient develops this inflammation over time by eating an excessive amount of a certain food group, or because their body has gone beyond its acceptance threshold for that food.

This is usually dealt with by gradually reintroducing the food until the body again digests it properly, without causing the discomfort the patient suffered.

Food inflammation is much less serious than an allergy or intolerance, but it can become a problem for the patient, as well as affecting other diseases already present in their body.

Food intolerance

The main difference is in the causes of the intolerance, as these originate in the digestive system rather than in the immune system.

Intolerance is specifically produced as a result of the absence of enzymes, protein molecules whose job is, among other things, to break down food. In relation to the symptoms, an intolerance can also appear in ways that remind us of inflammation and the less lethal symptoms of an allergy.

Not eating certain foods, consuming them in very small portions (only in specific cases) or looking for replacements are the main ways to deal with a food intolerance.

May interest you