Pumpkin seed

Further Reading

Pumpkin f225

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Code: f226
Latin name: Cucurbita pepo
Source material: Peeled seeds
Family: Cucurbitaceae
Common names: Pumpkin, Field pumpkin, Naked-seeded pumpkin, Pimpkin

Synonyms:  C. moschata, C. maxima, C. mixta, Cucumis pepo

Allergen Exposure

Geographical distribution

The Pumpkin is thought to have originated in Central America, possibly Mexico, but it is now grown widely in both temperate and tropical zones. It is an annual climber, typically with a large, round, ribbed, edible orange fruit. But Pumpkin comes in several other forms, such as the finer-textured, straw-colored Cheese pumpkin, the Gem squash and the Winter squash. All of these have a hard, smooth rind, sometimes lightly ribbed, covering edible flesh and the central seed cavity. Varieties within and between species can cross-pollinate to produce hybrids: hence the great number of shapes and sizes. Pumpkins, however, can be differentiated from other squashes by their fruit stalk: it is angular and polygonal in Pumpkins but thick, soft and round in other squashes.

Pumpkin seeds are consumed as a snack in many cultures throughout the world and are especially popular in Central American countries, where strains have been selected primarily for edible seed use. World production of the seed for food, on the other hand, is meagre.

Environment

The seeds, with their hulls intact, can be roasted or deep-fried and eaten as a salted snack, like nuts. Pumpkin seeds are a source of vegetable oil, but it is difficult to obtain because the seed is small and the fibrous hull must be removed. Flour may also be produced, and mixed with other cereals for making bread, etc. Fish bait is made from the seeds as well. The seeds can be sprouted and used in salads, etc. Pumpkin seeds are rich in protein.

The seeds are often used for medicinal purposes. (They are especially popular for tapeworm removal in pregnant women and small children, for whom harsher remedies are unsuitable.)

Unexpected exposure

The oil of the seed is sometimes used for lighting, but if pure, should contain no allergens.

Allergens

No allergens from this substance have yet been characterised.

In 3 Pumpkin seed-allergic individuals, immunoblot technique was used to isolate allergens of 13, 14, 36,  48, 77, and 87 kDa. The 14 kDa allergen appears to be a profilin (1).

Whether similar allergens are present in the seed and pulp has not yet been determined. Pumpkin pulp contains an ascorbate oxidase and a profilin (2).

Potential cross-reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected, as well as to a certain degree among members of the family Cucurbitaceae (3). Clinical cross-reactivity has been demonstrated among Pumpkin, Pumpkin seed, Muskmelon, Watermelon, Cucumber and Zucchini (4).

A cDNA clone encoding a Soybean allergen, Gly m Bd 28K, has been isolated, which exhibits high homology with the proteins in Pumpkin seeds and with a Carrot globulin-like protein. The clinical significance of this has not yet been determined (5).

Clinical Experience

IgE-mediated reactions

Pumpkin can induce symptoms of food allergy in sensitised individuals (4). Dermatitis, asthma, rhinoconjuctivitis, itching of the mouth, angioedema of the face and lips, generalised itching and mild dyspnoea after eating Pumpkin soup or vermicelli made with Pumpkin have been reported in a patient (4). Similar symptoms have been reported in 3 individuals after ingestion of roasted Pumpkin seed. All the patients fished for sport and used pressed Pumpkin seed flour as bait. IgE antibodies were detected to proteins from Pumpkin seed extract. Inhalation of Pumpkin seed flour during fishing was suggested as the route of sensitisation, leading to food allergy to Pumpkin seed (1).

Other reactions

Pumpkin seeds may be aspirated into the trachea in young children (6).

The sprouting seed produces a toxic substance in its embryo.

Compiled by Dr Harris Steinman, harris@zingsolutions.com

References

  1. Nielsen KK, Nielsen JE, Madrid SM, Mikkelsen JD. Characterization of a new antifungal chitin-binding peptide from sugar beet leaves.
    Plant Physiol 1997;113(1):83-91
  2. Berglund L, Brunstedt J, Nielsen KK, Chen Z, Mikkelsen JD, Marcker KA. A proline-rich chitinase from Beta vulgaris.
    Plant Mol Biol 1995;27(1):211-6
  3. Nielsen KK, Nielsen JE, Madrid SM, Mikkelsen JD. New antifungal proteins from sugar beet (Beta vulgaris L.) showing homology to non-specific lipid transfer proteins.
    Plant Mol Biol 1996;31(3):539-52
  4. Yman L. Botanical relations and immuno-logical cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09
  5. Zenaidi M, Pauliat S, Chaliier P, Fratta A, Girardet JP. Allergy to food colouring. A prospective study in ten children. [French] Tunis Med 2005;83(7):414-8

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.