Food allergies are immune system reactions where the body mistakenly identifies a harmless food protein as a threat, triggering a range of symptoms. These immune responses can vary in severity and affect different body systems.
How Citrus Allergies Develop
An allergic reaction to citrus fruits involves the immune system’s response to specific proteins within the fruit. The body produces immunoglobulin E (IgE) antibodies that recognize these proteins as harmful. Upon subsequent exposure, these IgE antibodies signal immune cells to release chemicals like histamine, which cause allergy symptoms.
Common symptoms of a citrus allergy can include itching or tingling in the mouth, hives, or swelling of the lips, face, tongue, and throat. Digestive issues like abdominal pain, nausea, vomiting, or diarrhea may also occur. In some instances, respiratory symptoms such as wheezing, nasal congestion, or difficulty breathing can develop. These symptoms typically appear within minutes to a few hours after consuming citrus.
Why Reactions Can Be Specific
While citrus fruits like grapefruit and oranges share some allergenic proteins, they also contain unique proteins or different concentrations of shared proteins. This explains why an individual might react to one citrus fruit but not another, as the immune system’s response can be highly specific.
Major allergens in citrus fruits include germin-like proteins (Cit s 1), profilins (Cit s 2), and lipid transfer proteins (LTPs, Cit s 3). Profilins are common pan-allergens found in many plants and pollens, and sensitivity to them can lead to oral allergy syndrome. Orange profilin, Cit s 2, has a high prevalence as an allergen in orange-allergic patients.
Lipid transfer proteins (LTPs) are another group of allergens found in citrus fruits, known for their resistance to heat and digestion. These proteins can cause more severe, systemic symptoms. While oranges contain Cit s 1, Cit s 2, and Cit s 3, grapefruit’s specific allergens are less characterized. The presence of specific proteins, their concentration, and structural variations across different citrus fruits can dictate the precise allergic response.
Recognizing and Addressing Citrus Allergies
Identifying a citrus allergy involves observing symptoms that range from mild to severe. Mild reactions might include localized itching or tingling around the mouth, or skin reactions like hives. More serious systemic reactions can involve widespread hives, difficulty breathing, a sudden drop in blood pressure, or even anaphylaxis, a life-threatening emergency.
Diagnosis typically begins with consulting a healthcare provider or allergist who will take a detailed medical history. Allergy testing, such as skin prick tests or specific IgE blood tests, can help identify sensitivities to citrus allergens. In some cases, an oral food challenge, conducted under medical supervision, may be necessary to confirm the diagnosis.
Managing a citrus allergy primarily involves strict avoidance of citrus fruits and products containing citrus derivatives. Reading food labels carefully is important, as citrus components can be present in unexpected items. For mild symptoms, over-the-counter antihistamines may offer relief. Individuals at risk of severe reactions, such as anaphylaxis, should carry an emergency epinephrine auto-injector and be educated on its proper use.