The symptoms of meat allergy are the same as those seen in other food allergies. The classic allergic reaction (anaphylactic) can manifest as urticaria, angioedema, itching of the mouth, lips and throat (oral allergy syndrome or OAS), asthma due to inhalation of cooking vapors and generalized anaphylaxis, sometimes induced by exercise or other cofactors, or of late presentation, when caused by alpha-gal (because this sugar is absorbed, bound to lipids, more slowly and by another mechanism).
Meat allergy may also manifest as allergic contact dermatitis and urticaria in patients who handle the food, or may rarely be the cause of exacerbation of atopic dermatitis.
Cases of occupational allergy have also been described, such as rhinitis and bronchial asthma caused by powdered albumin (beef and lamb meat), or by ham bone in charcuterie, and also by deposit mites present in ham.
In addition, meat can cause allergic digestive symptoms, such as eosinophilic esophagitis or other diseases such as protein enterocolitis.
Is it easy to diagnose this food allergy?
The diagnosis (which is sometimes complex) is based, as in other food allergies, on the preparation of a detailed clinical history (anamnesis) and the performance of allergic skin and/or analytical tests.
Sometimes it is not easy, from the anamnesis, to suspect this allergy because – besides being an infrequent cause of allergy (which is not usually thought of) – the reactions can be late (algae-gal), being difficult to establish a clear cause-effect relationship, or the presence of cofactors (exercise, alcohol or anti-inflammatory drugs) can be required for the allergic picture to be triggered.
In addition, the fact that the food is more or less cooked may influence the occurrence of the allergy because, due to the thermolability of some of the responsible proteins, cooking the food may denature or destroy the allergen, which would sometimes prevent the allergic picture from originating.
Meat allergy should be suspected in cases of anaphylaxis without apparent triggering factor (idiopathic), where ticks are endemic, so this food should be included in the battery of allergens to be studied in this pathology.
The confirmation of the suspicion of meat allergy should be carried out by means of allergic skin and/or analytical tests with the suspected meats and other relevant allergens, especially albumins and other allergens, such as alpha-gal, gelatins, epithelia or animal feathers as well as mites or fungi, depending on the clinical diagnostic suspicions.
Sometimes it may be necessary to perform provocation tests or controlled exposure with meat, if there are doubts in the diagnosis, or when it is desired to confirm tolerance to cooked meats or to check if the allergy has disappeared and tolerance has been achieved with the passage of time.
What treatment should meat-allergic patients undergo?
The basic treatment consists of the exclusion of the meat responsible for the allergy from the patient’s diet, bearing in mind that it may be necessary to avoid other meats with which there could be cross-reactivity. If the responsible allergen is albumins, it is possible that the meat can be eaten properly cooked. Other processes, such as homogenization or freeze-drying (production of baby food), can also alter allergenicity, as well as digestion with pepsin.
It should be borne in mind that meats can also be contained in processed foods (sausages, pates, etc.), so the labeling of these foods should be consulted before consumption to make sure that they do not contain them.
If the allergen is alpha-gal, all mammalian meat should be avoided. Patients allergic to this sugar should avoid the use of the antitumor drug (cetuximab), since, as it contains alpha-gal in its composition, it can cause allergic reactions.
In addition, patients with alpha-gal allergy may have reactions with organ meats (kidneys), food jellies or sweets, and those contained in certain drugs (vaccines, vaginal capsules, intravenous colloids or heparin) or valvular (cardiac) prostheses of bovine or porcine origin, as well as milk (some patients report poor tolerance to milk).
In patients allergic to meat, periodic evaluation is recommended to assess the possible establishment of tolerance, since they can, especially children, lose sensitivity as they grow and become tolerant to the food.
In case of allergic reaction the pharmacological treatment will be the same as that used in other food allergies, i.e.: antihistamines, corticoids and adrenaline. In anaphylactic patients it may be advisable for them to always carry auto-injectable adrenaline in order to be able to self-administer if they suffer an acute allergic reaction.