Celery is recognized globally as a significant food allergen, capable of causing reactions that range from mild discomfort to life-threatening emergencies. This adverse reaction is a true allergy, representing an overreaction of the immune system to specific proteins found within the plant, rather than a food intolerance. While this allergy is particularly common in central European countries, with reported prevalence rates up to 11.1% in some areas, it is increasingly recognized worldwide as a serious health concern.
Recognizable Symptoms of Celery Allergy
Reactions to celery manifest across a wide spectrum, with symptoms typically appearing quickly after ingestion or contact. The mildest and most common presentation is Oral Allergy Syndrome (OAS), characterized by itching, tingling, or slight swelling in the mouth, lips, or throat immediately upon eating raw celery. This localized reaction is usually temporary and does not progress further.
Celery allergy can also trigger severe, systemic reactions affecting multiple organ systems. These serious symptoms include the sudden onset of hives, widespread itching, swelling of the face, tongue, and throat, and gastrointestinal distress. The most life-threatening reaction is anaphylaxis, characterized by difficulty breathing, a sudden drop in blood pressure, and loss of consciousness. Celery is considered one of the foods most likely to trigger severe allergic episodes in sensitized adults.
The Immune Mechanism Behind the Reaction
A celery allergy is classified as an immediate hypersensitivity reaction involving the antibody Immunoglobulin E (IgE). In a sensitized individual, IgE antibodies are produced and attach to the surface of immune cells, primarily mast cells. When celery protein is consumed again, it binds to these IgE antibodies, signaling the mast cells to degranulate. This process releases inflammatory chemicals, most notably histamine, which causes the physical symptoms of the allergy. The immune system mistakenly labels harmless celery proteins as threats, such as the major allergen Api g 1. Other proteins, like the defensin Api g 7, are specifically linked to a higher risk of severe anaphylactic reactions.
Celery and Cross-Reactivity Syndromes
The connection between celery allergy and other substances is often explained by the concept of cross-reactivity, where the immune system reacts to structurally similar proteins found in different plant sources. Many celery allergies are secondary to a pre-existing pollen allergy, a link commonly referred to as Pollen-Food Syndrome. A frequent example involves the cross-reaction between celery and birch pollen, where the celery protein Api g 1 is structurally similar to the major birch pollen allergen, Bet v 1. A person first sensitized to birch pollen may later react to celery because their immune system cannot distinguish between the two similar proteins. This cross-reactivity often results in the milder Oral Allergy Syndrome symptoms.
A second, often more severe, cross-reactivity is known as Mugwort-Celery-Spice Syndrome. Individuals sensitized to mugwort pollen may experience reactions to celery, as well as to other foods in the Apiaceae family, such as carrots, caraway, anise, or coriander. This syndrome is linked to the celery defensin Api g 7 and the mugwort allergen Art v 1, and patients with this pattern have a significantly higher likelihood of experiencing systemic, life-threatening symptoms.
Identifying and Managing the Allergy
Diagnosis of a celery allergy typically begins with a thorough clinical history of the reactions, followed by specific tests to confirm sensitization. These diagnostic tools include skin prick tests, where a small amount of celery extract is introduced just beneath the skin’s surface to observe for a localized reaction. Blood tests are also performed to measure the level of specific IgE antibodies directed against celery proteins.
Management of a confirmed celery allergy centers on strict avoidance of the food in all its forms. Celery is frequently used as a hidden ingredient in many processed products, including spice mixes, stocks, soups, and certain seasonings, making careful label reading essential. Individuals with a history of systemic reactions are usually prescribed an epinephrine auto-injector, a device that delivers a dose of medication to reverse the effects of anaphylaxis. For mild, localized symptoms, an over-the-counter antihistamine may provide relief.