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. (1-3). 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. (1) 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. (1, 3, 4)

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. (6)

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. (7)

No allergens from this plant have yet been characterized.

A panallergen, a profilin, has been isolated from date pollen. (8). 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.(1)

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  sera from fruit-allergic as well as pollen-allergic patients recognise common fruit-specific epitopes; and that  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 utilizing 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.(9)

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.(8)

Cross-reactivity between date fruit and other foods containing LTPs is possible.(1)

Last reviewed:April 2022