Food allergy: what it is, treatment and prevention

A particular food can be harmless to some and extremely dangerous to others. A food allergy can appear unexpectedly and, without proper control, trigger emergency situations. 

It is estimated that this condition afflicts up to 10% of children and 5% of adults. In recent years, there has been an increase in the prevalence and severity, especially in children. Nevertheless, with specialised care, food allergies can be managed calmly and safely. 

In this article, we explain what food allergies are, how they differ from intolerances, which foods are most frequently involved, how they are diagnosed and what can be done to prevent and treat adverse reactions. 

Food allergy: what is it? 

A food allergy is an immune system response that occurs when the body mistakenly identifies certain proteins in food, which are tolerated by most people, as a threat. Even in extremely small quantities, contact with the food in question can trigger symptoms that range from mild to severe reactions. The most common symptoms include rashes, itching, swollen lips or throat, and difficulty breathing. In serious cases, anaphylaxis can occur, a systemic allergic reaction that requires emergency medical attention. 

5 foods that can trigger reactions 

The foods below are among the principal causes of allergic reactions to foods, which are often severe. 

Allergy to nuts 

Allergy to nuts – such as peanuts, walnuts, almonds and hazelnuts – is one of the most frequent and potentially dangerous food allergies. In many cases, exposure to small amounts or traces of these foods is enough to trigger a severe reaction, which can progress to anaphylaxis. Therefore, reading labels carefully and taking precautions in environments like schools or aeroplanes are crucial practices for people living with this condition. 

This type of allergy tends to be lifelong and requires a well-defined emergency plan. In addition to completely eliminating the food from one’s diet (elimination diet), many people should always carry adrenaline auto-injectors with them and inform relatives, friends and colleagues about their condition. In this case, prevention is a vital measure. 

Allergy to shellfish and fish 

Shellfish and fish are among the most common causes of food allergies in adults, although they also affect children. Symptoms can appear suddenly, even in people who previously tolerated these foods well. Exposure is not limited to direct ingestion; simple contact with the steam released during cooking can trigger reactions, which makes this allergy especially challenging in everyday life. 

It should be noted that allergies to fish and shellfish are caused by different proteins. Therefore, a person who is allergic to fish can often eat shellfish without any problem, and vice versa. Nevertheless, these allergies are frequently confused, leading some patients (sometimes even on medical advice) to avoid both groups, which may result in unnecessary dietary restrictions. An accurate diagnosis made by a professional with experience in allergology is essential to avoid unjustified limitations. 

The manifestations include rashes, vomiting, difficulty breathing and, in severe cases, anaphylaxis. As with other serious allergies, early diagnosis, an elimination diet and raising awareness among those around you are essential to ensure an effective response in an emergency. 

Allergy to eggs 

Allergy to eggs is one of the most common allergies in small children, although in many cases this tends to disappear with age. Reactions can be triggered both by the egg white and yolk, and the severity varies from person to person, from light rashes to more severe episodes, such as anaphylaxis. 

As eggs are a common ingredient in many processed foods, desserts and even some vaccines, this allergy requires extra care. It is essential for parents, teachers and caregivers to be informed, especially in a school environment, where food is frequently shared. 

An early diagnosis and regular medical follow-up help determine if the allergy persists or if the food can be reintroduced safely, in a controlled environment. 

Allergy to cow’s milk 

As with eggs, cow’s milk is a frequent allergy in childhood, and can even occur in infants who are still solely breastfeeding (through the mother’s milk). The symptoms range from gastrointestinal reactions, such as colic, vomiting or blood in stool, to cutaneous or respiratory signs. In severe cases, anaphylaxis may occur. 

This allergy is often confused with lactose intolerance, but they are different problems. While lactose intolerance is an inability to digest the sugar in milk, a milk allergy is an immune system response to milk protein. 

In time, most children outgrow this allergy but, until then, it’s necessary to strictly avoid all dairy products and guarantee a continuously balanced diet. In these cases, the support of a nutritionist can make a major difference. 

Food intolerances: which are the most common and how to diagnose them 

Not all reactions to food mean there is an allergy. In some cases, the body reacts adversely without involving the immune system — these are food intolerances. Intolerances are relatively common, vary from person to person and, although they are not life-threatening, they can compromise everyday wellbeing. 

The most frequent is lactose intolerance, caused by an inability to digest the sugar naturally present in milk and dairy products. This occurs due to a deficiency or absence of the lactase enzyme. Symptoms usually appear minutes or hours after consumption and include abdominal bloating, gas, colic, nausea and, sometimes, diarrhoea. It’s important to distinguish this condition from a milk allergy, which can cause severe reactions. Although uncomfortable, a lactose intolerance does not pose an immediate danger. 

In addition to lactose, there are other common food intolerances, such as gluten (in people who do not have celiac disease, but experience discomfort after ingesting wheat, barley or rye), fructose or certain food additives.  

Identifying these reactions can be challenging, especially when the symptoms are unspecific or occur sporadically. While there are several tests to identify food intolerance, it should be noted that, with except for the lactose intolerance test, there is no scientific evidence to validate most of these methods. Therefore, their use may cause confusion or lead to misinterpretations if they are not properly analysed by healthcare professionals. 

How to treat food allergies 

There is currently no definitive cure for food allergies. However, with the right care, they can be controlled effectively and safely. The first step is to obtain a medical diagnosis, usually provided by Allergology & Immunology specialists, through skin tests, blood tests or food provocation tests in a controlled clinical environment. Once the allergen has been identified, the key measure is to completely avoid the food in question. Although this may seem simple, this task can be challenging, as many allergens are present in less obvious ingredients. Therefore, it’s essential to learn to read labels carefully. In cases of severe allergies, it’s crucial to always have an emergency plan, which may include antihistamines or adrenaline auto-injectors. 

With information, vigilance and the right clinical support, it’s possible to live with a food allergy peacefully and safely. Today, many schools, restaurants and public spaces are aware of these conditions, making day-to-day management easier.