Food may trigger angioedema attacks through an intolerance — rather than an allergic — reaction, according to a small study published in the Orphanet Journal of Rare Diseases.
In hereditary angioedema (HAE), the immune system and blood flow processes may be excessively activated, causing episodic attacks of swelling — angioedema — and pain. This rare disorder can be life threatening when upper airways and abdomen are affected.
Specific factors or circumstances are thought to trigger angioedema attacks in the majority — 56% to 91% — of HAE patients. Emotions, trauma, infections, and hormone-related causes (in women) are the most frequent triggers of these attacks.
Recently, food has also been suggested as a trigger of angioedema attacks. While HAE patients consider that food-induced angioedema attacks are due to allergic reactions — which involve the immune system — the underlying mechanisms are uncertain.
Researchers investigated how allergic reactions to specific foods, medications, or bee/wasp venoms contributed to angioedema attacks in HAE patients.
The study, “Food as a trigger for abdominal angioedema attacks in patients with hereditary angioedema,” involved 42 individuals (27 women and 15 men) with a mean age of 45, from a larger group of HAE patients enrolled in the Swiss HAE cohort study.
Participants’ personal information, as well as self-reported trigger factors, intolerances, and symptoms were recorded. The presence of allergic reactions was assessed through skin and blood tests.
Trigger factors were reported by 79% of participants to cause angioedema attacks. Emotion was the most frequently reported factor (79%), followed by trauma (55%), and infection (39%).
Almost half of the participants reported either food (36%), medications (6%), or bee/wasp stings (6%) as the cause of their angioedema attacks.
Food triggers mentioned — including cheese, fish, tomatoes, strawberries, pineapples, nuts, citrus fruits, kiwis, and alcoholic beverages — were all reported to induce abdominal angioedema attacks.
Positive allergic reactions were identified in 29% of the 42 participants through skin allergy tests, with grass and tree pollen being the most prevalent sources. However, no difference in attack frequency was found between allergic and non-allergic patients.
“Based on our data, atopy [allergy] does not predispose HAE affected subjects to suffer from more frequent angioedema attacks,” the researchers wrote.
Also, skin and blood tests could not detect allergic reactions against any of the food triggers in the respective patients, suggesting that their angioedema attacks were caused by a non-immune reaction, such as intolerance.
The mechanisms behind intolerance reactions include the absence of a specific enzyme, increased susceptibility to certain chemicals in food, or the natural presence of histamine — the molecule involved in allergic reactions as part of the body’s immune response — in some foods.
Considering that most of the foods reported by as trigger factors contain or release histamine, the researchers hypothesized that an intolerance reaction against histamine may be the cause of these patients’ angioedema attacks.
But they noted this association is difficult to confirm, and there is no reliable laboratory test to provide an objective diagnosis related to food-inducing histamine intolerance.
The researchers added that a “careful individual nutritional counseling is recommended” for these patients, and that the study of HAE’s trigger factors is crucial to better understand the underlying mechanisms of this disease.