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|Latin Name||Castanea sativa|
|Common Name||Chestnut, European chestnut , Sweet chestnut|
See also: Sweet chestnut (Castanea sativa) f299
Not to be confused with horse chestnut (Aesculus hippocastanum) t203
The chestnut belongs to the Fagaceae family, which consists of 3 important genera: beech (Fagus), chestnut (Castanea), and oak (Quercus).
The European chestnut in its natural form is a large, spreading, deciduous tree, growing to over 30 m tall. Mature leaves are 10-20 cm long, 3-7 cm broad, and have between 6 and 20 bristles on each of the deeply serrated margins. Both female and male flowers are borne on the current season’s shoots, in early summer to midsummer. The trees are cold-hardy and can withstand temperatures as low as -25°C when dormant. The fruit (chestnut) is a spiny husk containing 2 or 3 nuts. In the USA, the chestnut pollen season extends from May to July. Chestnut trees are mainly insect-pollinated.
Several edible species of chestnut are grown around the world, the 4 main species being Chinese chestnut (Castanea mollissima), European or Spanish or sweet chestnut (C. sativa), Japanese chestnut (C. crenata), and American chestnut (C. dentata, most of which have been destroyed through a blight). The nuts of all of these species are used as food, in similar fashion (about which, see below).
Chestnut trees are cultivated in groves for fruit, and in coppices for wood. Up to 500 000 tonnes of chestnuts are produced each year around the world, with the biggest proportion coming from the northern hemisphere. Chestnuts are consumed fresh, boiled, grilled or preserved in sugar (iced chestnuts). Chestnut flour is also utilised. The tannin and the very hard wood of the tree are also used.
See sweet chestnut f299 for allergen information on these nuts.
European chestnut pollen has been shown to be present in honey, and may thereby contribute to allergic reactions. (1)
In an examination of sera from 14 patients with established allergy to pollen of the European chestnut, 13/14 (92%) showed IgE binding to a 22 kDa protein in European chestnut pollen extract, 2/14 (14%) displayed additional binding to a 14 kDa protein, and 1/14 (7%) bound only to the 14 kDa protein. The 22 kDa protein was characterised and is now known as Cas s 1. The 14 kDa protein was identified as a profilin. (2)
The following allergens have therefore been identified to date:
Cas s Profilin, a 14 kDa protein, a profilin. (2)
Ninety-two per cent of 14 patients with established allergy to pollen of the European chestnut tree demonstrated specific IgE to the profilin allergen in this pollen. Fourteen per cent displayed additional binding to a 14 kDa protein in the extract, and 1 (7%) bound only to this 14 kDa protein. (2)
The chestnut belongs to the Fagaceae family, which consists of 3 important genera: beech (Fagus), chestnut (Castanea), and oak (Quercus). Extensive cross-reactivity between the different individual species of the Fagaceae family could be expected. (5, 6, 7)
Cas s 1 shows significant amino acid sequence similarity, and antigenically is closely related to the major birch pollen allergen Bet v 1. (3) Cross-reactivity with other Bet v 1-related allergens occurs, including with birch tree.
Profilin from pollen of the European chestnut would be expected to cross-react with other plants containing profilin. (2, 8)
IgE-mediated allergy (resulting in hay fever and asthma) to pollen of the European chestnut represents an important cause of pollinosis in Mediterranean and sub-Mediterranean areas. (9, 10, 11, 12, 13, 14, 15)
Skin-prick tests to chestnut pollen were positive in 17/47 patients with seasonal symptoms of allergy in a study conducted in Paris. Eight patients had total IgE levels above 300 kU/l, 15 were found to have IgE antibodies to the pollen, and 14 were positive on nasal provocation testing. (10) In the southern part of Switzerland (Canton Ticino), where chestnut pollens represent about 30% of the airborne pollens, 37% of 503 patients with allergic rhinitis were sensitised to European chestnut pollen. (9)
A study examined the impact of different trees on asthma, and the association between daily hospitalisations for asthma and daily concentrations of different tree pollens in 10 large Canadian cities, and found that as a result of an interquartile increase in daily tree pollen concentration, percentage increases in daily hospitalisation for asthma were 2.32% for the group containing Quercus and Castanea. (16)
In a study of 210 patients with a diagnosis of pollinosis who attended an allergy clinic based in Plasencia, Spain, a low prevalence of sensitisation to Chestnut tree of 7.1% was demonstrated. Sensitisation to other pollens was far more prevalent: Dactylis glomerata, 80%; Olea europea, 72%; Fraxinus excelsior, 68%; Plantago lanceolata, 63%; Chenopodium album, 61%; Robinia pseudoacacia, 49%; Artemisia vulgaris, 44%; Platanus acerifolia, 37%; Parietaria judaica, 36%; Populus nigra, 32%; Betula alba, 28%; Quercus ilex, 21%, Alnus glutinosa, 21%; and Cupressus arizonica, 8%. Of the 15 patients sensitised to chestnut pollen, 14 had seasonal rhinoconjunctivitis and asthma. Ten patients had IgE antibodies to chestnut pollen. Chestnut pollen was shown to be present in this area in large amounts from the 23rd to the 28th week of the year. (15)
Chestnut wood has also been shown to cause occupational asthma in wood workers. (17)
Allergic reactions often occur following ingestion of the fruit (nut) of the chestnut tree. See sweet chestnut (Castanea sativa) f299.