Immunology, Rheumatology, Allergology and Rare Diseases
31-05-2024
Food Allergies and Intolerances: What They Are and How to Tell Them Apart
Publication date: 26-05-2025
Updated on: 26-05-2025
Topic: Immunology, Rheumatology, Allergology and Rare Diseases
Estimated reading time: 1 min
Article Author
Lara Benvenuti
Medical Editor
Patrizia Giollo
Medical Editor
Giovanni Lasagni
Editor and Translator
Viktoryia LuhakovaMore and more often, we hear about food allergies and intolerances, terms that are frequently confused. This confusion has led to uncertainty not only in terminology but also in how these conditions are diagnosed and managed.
In recent years, the number of proposed diagnostic methods has increased significantly, many of which lack scientific validation. This has further complicated the understanding and management of these issues.
We discuss this with Dr. Patrizia Giollo, gastroenterologist, and Dr. Giovanni Lasagni, allergist, both from IRCCS Ospedale San Raffaele, where a dedicated clinic for food allergies and intolerances is available.
Food allergies and intolerances: what they are and how they differ
Both food allergies and intolerances are adverse reactions to food, but they differ in their underlying pathophysiological mechanisms.
Food allergies are reactions mediated by the immune system. When the body mistakenly identifies a food as harmful, it triggers an immune response involving the production of IgE antibodies, which lead to allergic symptoms. These reactions can range from mild symptoms to severe ones, such as anaphylaxis.
Food intolerances, on the other hand, are non-immunologic adverse reactions, often related to the body's difficulty in digesting or metabolizing certain foods, such as in the case of lactose intolerance. Causes of food intolerances may include:
- Enzyme deficiencies
- Unbalanced diets
- Use of antibiotics
- Alterations in the gut microbiota
What are the symptoms?
The confusion between allergies and intolerances often stems from the similarity of their clinical presentations. Although the mechanisms are different, both conditions can produce similar symptoms, making it difficult to distinguish between them without proper diagnosis. These symptoms may include:
- Gastrointestinal discomfort
- Heartburn
- Abdominal bloating
- Skin rashes
“Symptoms that appear after eating a pizza, for example, may be due to lactose or gluten intolerance, or more rarely an allergy to cow’s milk or wheat proteins. For this reason, when symptoms primarily involve the gastrointestinal tract, making a definitive diagnosis can be complex, and patients should be evaluated by a multidisciplinary team,” explain the two specialists.
The multidisciplinary clinic for food allergies and intolerances at San Raffaele
The Multidisciplinary Clinic for Food Allergies and Intolerances at IRCCS Ospedale San Raffaele is part of both the Unit of Rheumatology, Allergology and Rare Diseases, led by Professor Lorenzo Dagna, and the Unit of Gastroenterology and Digestive Endoscopy, led by Professor Silvio Danese.
Through an integrated assessment by both allergists and gastroenterologists, a personalized diagnostic and therapeutic pathway can be defined, ensuring comprehensive care for the patient. This approach helps to avoid unnecessary food restrictions and nutritionally unbalanced diets, often based on unvalidated tests.
The clinic also offers dietary support with a dedicated dietitian for patients diagnosed with food allergies.