What Is a Food Allergy and Which Are the Most Common?

Healthy nutrition, rich in fresh and seasonal foods, is the first step in keeping the gut flora balanced.

In recent years, food allergies have increased worldwide, and it is estimated that in Spain this increase is around 7.4%. As Raquel Soriano, a general practitioner at SHA Wellness Clinic, tells us, ‘A food allergy is an inappropriate reaction to the ingestion, contact or inhalation of a specific external agent, known as an allergen. It occurs when the immune system mistakenly identifies a food or a substance present in it as harmful and, in response, releases antibodies, called immunoglobulin E, to neutralise it’.

Not all the factors that influence this increase are yet known, but what is clear is that environmental factors play a role. ‘Pollution, an unhealthy lifestyle, and nutrition are fundamental. We know that a diet based on ultra-processed foods and rich in sugars causes a variation in the intestinal flora. As a result, this may be one of the main reasons for the increase.

Genetic factors also play a role: if there is a history of allergic disease in a family, the likelihood of any of the offspring suffering from allergic disease increases by 5-15%. Although the genetic code cannot be altered, thanks to epigenetics we can modulate, activate, or deactivate the expression of genes without modifying the DNA sequence. In other words, a certain genetic tendency can be reversed with healthy lifestyle habits,’ adds Raquel. To learn more about the role of food in gene function, Click here

However, not all adverse food reactions are the same. As the doctor explains, ‘There are toxic ones, which are intoxications, and anyone can suffer from them. For example, if you eat poisonous mushrooms. And then there are the non-toxic ones, which are divided into three groups:

• immunoglobulin E-mediated immunological ones, which are food allergies.
• non-immunoglobulin E-mediated immunological ones, such as coeliac disease
• non-immunological ones, which are intolerances, such as lactose intolerance’.

Food allergies are highly dependent on geography because they are directly related to diet and, in different countries and cultures, the most commonly consumed foods vary. In Spain, the most common allergies are to cow’s milk protein, eggs, fish, seafood, pulses, especially lentils and soya, and grains. In the United States, on the other hand, it is peanuts.

Dr Soriano stresses one element that is important to bear in mind: cofactors. ‘There are situations in which the threshold of tolerance to the allergen may decrease and this entails the risk of suffering a reaction with a dose that was previously tolerated. The most important cofactors are exercise, infections, alcohol, fasting, stress, anti-inflammatory drugs, and proton pump inhibitors. As such, there are people who can tolerate a minimal amount of a food with an allergic basis, but who, when consuming it in these situations, still suffer the reaction’.