Date

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Code: f289
Latin name: Phoenix dactylifera
Source material: Fruit
Family: Arecaceae
Common names: Date, Date fruit, Soft date, Bread date, Dry date

See also Canary Island date palm tree (Phoenix canariensis) t214.

Food

A food, which may result in allergy symptoms in sensitised individuals.

Allergen Exposure

Although there are many palms that we call ‘date palms’, Phoenix dactylifera is the true date palm, with a 5 000-year history of human use. Dates require a hot, dry climate and flourish in Africa, the Middle East, California, and Arizona. Although there are at least 150 varieties, there are 2 main types: dry and bread dates are self-curing on the tree; soft dates require harvest at the appropriate time, and sun-drying to increase sugar content and prevent spoilage. The latter are traditionally packaged in palm leaves and widely traded. The date is often the only available staple food for the inhabitants of desert and other arid lands, and as such it is vital to millions throughout North Africa and the Middle East.

The fruit of the date is a drupe and can vary in size, shape, colour, and quality of flesh. Dates are usually reddish-brown when fully ripe. The maximum length of the fruit is about 6 cm. All dates have a single long, narrow seed. The skin is thin and papery, the flesh cloyingly sweet. Wild dates are morphologically and ecologically similar to domesticated dates, but have smaller, inedible fruits.

Edible dates are produced only by cultivation. When fresh, dates contain about 55% sugar, a percentage that increases dramatically as the date dries and the sugar becomes concentrated. Dates can be eaten fresh, but are usually marketed dried, and sometimes as a syrup. They yield food products such as vinegar, wine, ‘honey’, chutney or sweet pickle, paste for bakery products, and flavourings; in particular, additional flavouring for oranges, bananas and almonds. Date syrup is a sugar substitute. Date sap is made into a fermented beverage, and a flour is made from the pith of the tree. The seeds yield an edible oil. Even the tree's terminal buds (heart of palm) make tasty additions to vegetable salads. Dates are a good source of protein, iron, fibre, potassium, and vitamin C.

Regarded as aphrodisiac, contraceptive, demulcent, diuretic, emollient, expectorant, laxative, pectoral, purgative, and refrigerant, the date is used in many folk remedies, especially for respiratory complaints and diseases of the gentio-urinary system. A plaster of the nuts or of the bark is also a folk remedy.

The leaves are used for making ropes, mats, baskets, crates, furniture, fencing and roofing. The base of the leaf and the fruit stalk is used as fuel. The wood is used for construction, and the seed oil for soap manufacture.

Allergen Description

No allergens from this plant have yet been characterised.

A panallergen, a profilin, has been isolated from date pollen. (1)

The presence of another panallergen, a lipid transfer protein (LTP), has been inferred from a study assessing foods that may be regarded as safe for LTP-allergic patients. (2)

Date fruit extracts from 8 cultivars were evaluated for skin-specific IgE in an atopic population. About 13% of patients were shown to have skin-specific IgE to at least 2 date fruit extracts. Between 15 and18 proteins of 6.5 to >100 kDa were detected. All sera from date fruit-allergic and pollen-allergic individuals bound strongly to 2 anti-IgE reactive bands of 6.5 to 12-14 kDa and 28-33 kDa, respectively; and about 50% of sera bound to a 54-58-kDa band. The authors state that these results strongly indicate that 1) date fruit is a potent allergen; that 2) sera from fruit-allergic as well as pollen-allergic patients recognise common fruit-specific epitopes; and that 3) there is heterogeneity in patient responses to the different extracts. (3)

In a subsequent study, 18 of the most commonly sold varieties of dates were investigated for allergenicity utilising a study group of 32 date fruit-sensitive patients. Six of the cultivars demonstrated high skin-specific IgE in some patients, and 5 were associated with high serum-specific IgE levels. However, individual cultivars varied in the number of IgE bands seen. Cultivar-specific IgE-binding patterns showed that only certain cultivars bound IgE at molecular weights of < or =14.3 and 27-33 kDa, while all cultivars bound to a 54-58 kDa doublet. Cultivars that bound to the < or =14.3 and 27-33 kDa bands appeared to form the majority of the cultivars resulting in high skin-specific IgE. When individual sera of 24 of the 32 skin-specific IgE patients were used in IgE immunoblots with the pooled cultivar extract, all sera bound IgE at < or =14.3 and 27-33 kDa, and about 60% of sera bound to the 54-58 kDa doublet. Sixty to 100% of sera from date fruit-allergic patients bound IgE to 3 major allergens of around 14.3, 27-33 and 54-58 kDa. The authors concluded that the allergenicity of Date fruits is a cultivar-specific phenomenon. (4)

Potential Cross-Reactivity

Extensive cross-reactivity among the different individual species of the genus could be expected. (5)

Date fruit and pollen antigens share a number of cross-reactive epitopes. Date pollen has been shown to cross-react with antigens from Artemisia species, cultivated rye (Secale cereale), Timothy grass (Phleum pratense), Sydney golden wattle (Acacia longifolia), and Bermuda grass (Cynodon dactylon) pollen. A study was carried out to examine cross-reactivity between date palm protein and some common foods that have been implicated in oral allergy syndrome (OAS). Several antigens were shown to be cross-reactive among birch, date and Timothy grass profilin. Sixty-six percent of sera from date-hypersensitive individuals bound IgE to date fruit profilin, and pooled sera bound IgE to birch pollen profilin. The authors suggest that these results indicate that date palm protein shares cross-reactive IgG and IgE epitopes with a number of foods implicated in OAS; binds to birch and Timothy grass profilins; and binds IgE through glycosyl residues. They state that the clinical relevance of these cross-reactivities needs to be further elucidated. (1)

Cross-reactivity between date fruit and other foods containing LTPs is possible. (2)

Clinical Experience

IgE-mediated reaction

Date fruit may commonly induce symptoms of food allergy in sensitised individuals, in particular in communities where this fruit is commonly ingested. (2, 3, 6 )In a population where date fruit is commonly eaten, the presence of skin-specific IgE to at least 2 date fruit extracts was shown in approximately 13% of the study group of atopic patients. Eight cultivars were evaluated. (2) Allergic reactions may include symptoms of immediate hypersensitivity: pharyngeal pruritis, oedema of the lips, dyspnoea, wheezing, dysphagia, dysphonia, oral allergy syndrome, and other symptoms of food allergy. (2, 3, 7)

A study was conducted at 17 clinics in 15 European cities to evaluate the differences between some Northern countries regarding what foods, according to the patients, elicit hypersensitivity symptoms. According to questionnaires administered to food-allergic individuals concerning 86 different foods, the foods that most often elicited symptoms in Russia, Estonia, and Lithuania were citrus fruits, chocolate, honey, apple, hazelnut, strawberry, fish, tomato, hen’s egg, and cow’s milk; a situation that differed from that of Sweden and Denmark, where birch pollen-related foods such as nuts, apple, pear, kiwi, stone fruits, and carrot were the most common reported causes. The most common symptoms reported were oral allergy syndrome and urticaria. Birch pollen-related foods dominated as reported culprits in Scandinavia, whereas some mugwort-related foods were of more importance in Russia and the Baltic States. Among 1 139 individuals, apricot was the 76th most-reported food, resulting in adverse effects in 5.3%. (5)

Other reactions

Dates contain tyramine, which may cause migraine in susceptible people. Since dates are high in sugar, they may cause tooth decay and gum disease.

Edible dates have been reported to contain the moulds Cladosporium cladosporioides and Sporobolomyces roseus. Both organisms have been previously reported in opportunistic infections involving skin in immunocompromised patients. (8)

In a study, 25 varieties of dates (Phoenix dactylifera) were examined at different maturation stages for total microbial counts, aflatoxins and aflatoxigenic Aspergillus species, and lactic acid bacteria. Microbial counts were high at the first stage of maturation and increased sharply at the second stage, then decreased significantly at the final, dried stage. Aflatoxins were detected in 12% of the samples, while aflatoxigenic Aspergillus was detected in 40% of the varieties examined; all at the first stage of maturation only. No aflatoxins or aflatoxigenic Aspergillus were detected at the final, edible stage of maturation. (9)

Compiled by Dr Harris Steinman, harris@allergyadvisor.com

References

  1. Kwaasi AA, Harfi HA, Parhar RS, Saleh S, Collison KS, Panzani RC, Al-Sedairy ST, Al-Mohanna FA. Cross-reactivities between date palm (Phoenix dactylifera L.) polypeptides and foods implicated in the oral allergy syndrome. Allergy 2002;57(6):508-18.
  2. Asero R, Mistrello G, Roncarolo D, Amato S. Detection of some safe plant-derived foods for LTP-allergic patients. Int Arch Allergy Immunol 2007;144(1):57-63.
  3. Kwaasi AA, Harfi HA, Parhar RS, Al-Sedairy ST, Collison KS, Panzani RC, Al-Mohanna FA. Allergy to date fruits: characterization of antigens and allergens of fruits of the date palm (Phoenix dactylifera L.). Allergy 1999;54(12):1270-7.
  4. Kwaasi AA, Harfi HA, Parhar RS, Collison KS, Al-Sedairy ST, Al-Mohanna FA. Cultivar-specific IgE-epitopes in date (Phoenix dactylifera L.) fruit allergy. Correlation of skin test reactivity and ige-binding properties in selecting date cultivars for allergen standardization. Int Arch Allergy Immunol 2000;123(2):137-44.
  5. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09.
  6. Eriksson NE, Moller C, Werner S, Magnusson J, Bengtsson U, Zolubas M. Self-reported food hypersensitivity in Sweden, Denmark, Estonia, Lithuania, and Russia. J Investig Allergol Clin Immunol 2004;14(1):70-9.
  7. Gonzalo MA, Moneo I, Ventas P, Polo F, Garcia JM. Immediate hypersensitivity reaction to date. Allergy 1997;52(5):598-9.
  8. Moore JE, Xu J, Millar BC, Elshibly S. Edible dates (Phoenix dactylifera), a potential source of Cladosporium cladosporioides and Sporobolomyces roseus: implications for public health. Mycopathologia 2002;154(1):25-8.
  9. Shenasi M, Aidoo KE, Candlish AA. Microflora of date fruits and production of aflatoxins at various stages of maturation. Int J Food Microbiol 2002;79(1-2):113-9.

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