Due to the similarity in some of their symptoms, allergies and food intolerances are often confused. However, they are two distinct conditions that differ in their origin: allergies are triggered by an immune system reaction, while intolerances are due to a metabolic issue in the digestive system. Below, we explore their differences.
Definition
Food Allergy: A food allergy is an immune system reaction to an allergen (protein) in foods.
Food Intolerance: Generally, a food intolerance is the body’s response to the digestive system’s inability to process or digest a food or one of its components. However, some intolerances, such as non-celiac gluten sensitivity, are not due to the inability to digest a component but rather a physiological reaction that causes digestive and extra-digestive symptoms without involving a specific immune or enzymatic process. Additionally, the cause of many intolerances remains unknown.
Causes
Food Allergy: It occurs when the body comes into contact with an allergen, a protein that the body perceives as a threat. In response, the immune system activates an inflammatory process and generates antibodies to defend itself. The most common food allergies are to cow’s milk, eggs, nuts, fruits (especially peaches), and seafood.
Food Intolerance: Generally, this is due to the digestive system’s sensitivity to a component of a food, caused by an enzyme deficiency. Unlike allergies, the immune system is not involved. For example, lactose intolerance occurs due to the decrease of lactase enzymes present in the lining of the intestine, which are responsible for breaking down and metabolizing lactose. Without these enzymes, lactose is not properly digested, causing digestive issues like fermentation and gas production. The most common intolerances are to lactose, sucrose, and fructose, found in fruits, vegetables, and sweeteners.
Symptoms
Food Allergy: In the case of allergies, although the reaction typically occurs immediately after eating the food (within minutes to hours), there are also some delayed allergic reactions that can appear several hours later, such as cow’s milk protein allergy in some children. Symptoms may include itching in the mouth, swelling of the lips or eyelids, sneezing, nasal congestion, tearing, redness, skin rashes, difficulty breathing, intestinal disturbances, or even more severe reactions such as low blood pressure and loss of consciousness. The combination of these symptoms is known as anaphylaxis.
Food Intolerance: Symptoms can appear gradually and depend on the amount of food consumed. It mainly manifests with gastrointestinal discomforts such as abdominal pain, bloating, or diarrhea.
Diagnosis
At any sign that suggests the presence of a food intolerance or allergy, it is essential to consult a specialist to help identify the responsible food.
Food Allergy: The allergist is the one who conducts food allergy tests. Initially, a patient’s medical history will be taken, and this will be supplemented with provocation tests. Additionally, at CreuBlanca’s Allergy Unit, we also perform the well-known Skin test or prick test (skin allergy test) to detect sensitization to substances or probable foods responsible for the allergic reactions. The test consists of introducing a drop of the allergen into the most superficial layer of the skin through a light prick in the forearm area. The prick is done with a lancet, not a needle, so the test is painless. The magnitude of the skin reaction will provide information about the likely foods causing the allergic reaction.
Food Intolerance: In the presence of signs of intolerance to a food, the specialist in Gastroenterology may suggest different diagnostic tests to detect them. Additionally, there is the Breath Hydrogen Test, used to detect malabsorption of certain substances, such as lactose, sorbitol, or fructose.
Treatment
Once the allergy or intolerance is identified, the specialist will determine the most appropriate preventive treatment for each patient. In general, avoiding or restricting the consumption of the food causing the allergy or intolerance is advised.
In some specific cases, medications will be prescribed to relieve possible symptoms that may appear in case of accidental ingestion.
In most food intolerances, the main treatment is dietary modification. In certain cases of intolerances, medications may be prescribed for specific symptoms or to assist digestion (for example, lactase supplements, the enzyme that breaks down lactose). There are no medications to treat food intolerances themselves.
The Allergology Unit and the Gastroenterology Unit at CreuBlanca have a multidisciplinary team of highly specialized professionals in the diagnosis and treatment of various food-related conditions and disorders. At any sign of food intolerance or allergy, our doctors will evaluate your case thoroughly, offering support throughout the diagnostic process. Additionally, they will provide personalized treatment tailored to your specific needs, helping you enjoy a healthy lifestyle, improve your quality of life, and prevent complications or adverse effects.