Know what you're eating

Halloween and a pumpkin allergy

Halloween and a pumpkin allergy

Halloween (a contraction of Hallows' Even or Hallows' Evening) is a celebration observed on the night of 31 October. It is most widely celebrated in Anglo-Saxon countries and its roots are linked, in addition to some Celtic festivals, to the Christian holiday of All Saints’ Day, celebrated by Catholics on 1 November.

One of the best-known symbols of Halloween is the image of a hollowed-out pumpkin with holes carved in the surface to create a grotesque or macabre face: a symbol called “jack o'lantern” when a lit candle is placed inside the hollowed-out and carved pumpkin so that it can be used as a lamp.

Pumpkin as an allergen

Pumpkin is not one of the 14 allergens included under the special regulation established by Regulation (EU) No 1169/2011 of the European Parliament and of the Council. Although it is not a frequent allergy, those people who are allergic to pumpkin, and especially to its seeds (pips), should be very careful about the ingredients in canned and packaged processed foods, as well as about what is in non-packaged foods served in restaurants and bars. They should also be aware that some commercial baking mixes contain pumpkin seed powder or extracts. Moreover, it is advisable to avoid the skin coming into contact with pumpkins and their seeds.

Pumpkins are members of the Cucurbitaceae family, which also includes the courgette, cucumber, melon and watermelon. Pumpkins are, specifically, of the Cucurbita genus, and originally from America, where they grow in the wild from the temperate-cool areas of the United States to parts of Argentina and Uruguay. Some pumpkin species are extensively cultivated for their rounded and edible fruit, of which the pulp and seeds are consumed.

Allergy to the pulp and seeds has been recorded. These seeds, once dried, can be consumed independently, as if they were nuts (pumpkin seeds). Although it was thought that people allergic to pumpkin pulp would also be allergic to its seeds, a review by Patel and Bahna, published in 2016 in the journal Allergy, “Hypersensitivities to sesame and other common edible seeds” suggests that the opposite is true, that is, a pulp allergy and a seed allergy may not be associated.

The route of entry, in addition to being digested, can be cutaneous (they can cause dermatitis or hives in people with a reaction who touch the pulp or seeds) or even respiratory (by inhalation of the pulp cooking fumes).

There may be a cross reaction with other members of the Cucurbitaceae family: that is, a person allergic to pumpkins may also be allergic to courgettes, cucumbers, melons or watermelons. In some of these cases, cross reactivity withragweed pollen has also been described, in an example of what we call pollen-food allergy syndrome.

Although the allergens in this vegetable that cause allergies have not yet been satisfactorily identified, and we do not even know if the same ones are present in the pulp and the seeds (although thanks to the data referred to above it can be assumed that at least the main ones are different), we know that one of the protein allergens identified in pumpkin pulp is profilin. When the food allergy is the result of a reaction to this molecule, the symptoms are usually limited to the oral cavity and its surroundings, producing oral allergy syndrome. This is because the molecules are sensitive to the acidic pH of the stomach and some digestive enzymes.

On other occasions, in contrast, the picture may evolve into anaphylaxis: according to the same review by Patel and Bahna mentioned earlier, of the five published cases of allergic reactions after eating pumpkin seeds, four of them presented as anaphylaxis.

Currently, the only possible treatment for people who are allergic to pumpkins is to avoid any food containing them.

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