Latin name: Solanum melongena
Source material: Fresh fruit
Common names: Aubergine, Eggplant, Brinjal, Garden egg, Jew’s apple, Mad apple, Pea apple, Egg apple, Guinea squash
S. melongena - East Indian Aubergine
S. melongena esculentum - Common Aubergine
S. melongena depressum - Dwarf Aubergine
S. melongena serpentium - Snake Aubergine
Aubergine is a member of the nightshade (Solanaceae) family, which includes Tomato, Potato, and Bell pepper.
The cultivated Eggplant, Solanum melongena, is a species of considerable economic importance in many tropical and subtropical parts of the world (1). Eggplant is native to India or Africa. It spread eastward clear to Japan, and was introduced to Europe as early as the 13th century AD. From there it spread early to North and South America. The most important countries of production are China, Turkey, Japan, Egypt and Syria. It is often called “the poor man’s meat”, as it is rich in nutrients.
Eggplant is a perennial plant, but is cultivated as an annual. It is spiny and grows as high as 2 m, and has star-shaped, blue-violet leaves. Though commonly thought of as a vegetable, Eggplant is actually a fruit, specifically a berry. The fruit varies in shape from round to oblong, in size from a few centimetres to 30 cm, and in colour from dark violet to white. In the United States, the most common Eggplant is the large cylindrical or pear-shaped variety with a smooth, glossy, dark-purple skin. It is available year-round, the peak season being August and September.
Eggplants are unknown in any wild variety, and their cultivation requires abundant water and warmth. They can be prepared in many ways: in stews, roasted or grilled, sautéed, stir-fried, breaded and fried, baked, pickled or stuffed.
Aubergines may contain large quantities of histamine. They cannot be eaten raw due to the potentially dangerous amounts of solanine they contain in that state.
In Suriname’s traditional medicine, the roots of the Eggplant are used against internal haemorrhage and asthma, the leaves and bark against dysentery.
No allergens from this plant have yet been characterised, although several IgE-binding Eggplant proteins have been reported (2). Recently, protein bands of 71, 64 and 60 kDa were detected in sera of 3 Indian Eggplant-allergic individuals. The 71 kDa protein appears to be heat-stable (3). The same authors subsequently reported on a 31-year old-individual with allergy caused by ingestion of Eggplant, in whom skin prick testing was positive with 4 varieties of Eggplant but with negative Aubergine IgE antibody levels. Laboratory analysis revealed that the causative allergen was a low-molecular-weight non-protein secondary metabolite of less than 1 kDa (4). The authors point out that possible non-protein but reaction-causing compounds in Eggplant include pigments (cyanidin, delphinidin, lycoxanthin, and nasunin), alkaloids (solamargine, solanidine, solanine, solasodine, solasonine, and trigonelline), and phytosterols (5). The alkaloid properties of Aubergine have been suggested as the cause of occasional sensitivities to Aubergine (6), though direct evidence is still lacking (4).
In a Korean individual who experienced anaphylaxis to Aubergine with cross-reactivity to Latex, 3 IgE-binding proteins were identified from fresh and cooked Aubergine: 1 band between 22 and 36 kDa, 1 band near 36 kDa, and 1 band between 36 and 50 kDa (7).
A lipid transfer protein has been detected in Aubergine (8). In an allergenicity assessment of the related Ethiopian eggplant (Solanum aethiopicum), profilin and lipid transfer proteins have been detected (9).
Eggplant is a member of the Nightshade family; it is closely related to the Potato and the Tomato. 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 Solanaceae (2,10). This is supported by research reporting that antigenically cross-reactive material from Tobacco leaf could be found in Eggplants, Green peppers, Potatoes, and Tomatoes, which are all members of the family Solanaceae (11).
Allergic reactions to Eggplant in subjects with Parietaria pollen sensitisation have been reported (12).
A lipid transfer protein has been detected in Aubergine, which may result in cross-reactivity with other lipid transfer protein-containing foods (8).
Anaphylaxis to Eggplant was described in a patient with Latex allergy. Further investigation demonstrated that a protein in boiled Eggplant (and to a lesser degree, raw Eggplant) significantly inhibited Latex antigen. One IgE-binding component with the same molecular weight (between 22 and 36 kDa), from Eggplant and Latex, was detected as a candidate for the cross-reactivity; the protein did not display cross-reactivity with Potato (7). The clinical significance of this cross-sensitisation was illustrated in a 31-year-old Spanish woman with Latex allergy who was also allergic to Banana and Eggplant, as shown by case history and a skin prick test (13).
Aubergine can induce symptoms of food allergy in sensitised individuals (4,8,12-13). But food allergy to ingesting the fruit of this plant is uncommon; reactions have been attributed to cross-reactivity with Tomato and grass pollen allergens in 1 individual (2), and with Parietaria pollen allergen in 5 cases (12).
Eggplant allergy following ingestion of the fruit has been described in 5 individuals, who were also sensitised to Wall pellitory (Parietaria) pollen: 3 women and 2 men aged between 24 and 50 years. In 3 cases, symptoms of OAS were reported (only oropharyngeal symptoms in 1; another also had symptoms of cough and dysphonia, and 1 had vomiting). Two had systemic symptoms as well (1 urticaria, 1 anaphylaxis) (12).
In a random survey of 500 individuals in India, 66 (11%) were reported as having Eggplant allergy, based on case history and skin tests. The authors suggest that this high incidence is probably due to the presence of histamine and serotonin in the plant. In this report, 3 cases of allergy following ingestion of Aubergine were described:
- A 23-year-old woman with itchiness and an unpleasant feeling while eating food prepared with Eggplant. There was immediate rash, and facial oedema in about 20 minutes.
- A 25-year-old man who developed itching within 15 minutes after eating any food prepared using Eggplant. Within an hour, the rash became prominent, with itching of the throat and hoarseness.
- An 18-year-old-girl developed itching in the throat and of the skin within 30 minutes of the ingestion of Eggplant. Generalised uricaria with severe pruritis developed within 1 to 2 hours. SPT and prick-to-prick tests were positive in all 3. IgE antibodies to raw and cooked Eggplant were detected (3).
An Indian study reports on allergy caused by ingestion of Eggplant in a 31-year-old man. His allergy to Aubergine had clearly manifested at the age of 10 years, although symptoms had been first noticed by his mother at the age of 6. He experienced itching or discomfort while eating curry or other foods containing Aubergine. Within 1 to 2 hours of consuming foods containing Aubergine, itchy skin rashes appeared all over the body, along with itching of the throat and hoarseness. Skin prick tests were positive with 4 varieties of Eggplant; however, serum Aubergine-specific IgE antibodies were not detected. It was suggested that the causative allergen was a low-molecular-weight non-protein secondary metabolite of less than 1 kDa (4).
A 31-year-old Spanish woman developed anaphylaxis after eating Banana. She had had a previous diagnosis of Latex-fruit syndrome after presenting with rhinitis and skin and pharyngeal pruritus after eating Chestnut. She also experienced angioedema of the face and hands, conjunctivitis, generalised pruritus, glottic oedema and difficulty in breathing immediately after ingesting Aubergine (13).
Eggplant fruit has induced IgE-mediated immediate-type hypersensitivity reactions, such as rhinorrhoea, urticaria, food allergy and asthma (2).
An Indian study evaluated the possible effect of a specific elimination diet on symptoms of 24 children aged 3 to 15 years with documented deterioration in control of their perennial asthma. IgE antibody analysis for a range of food items found that 22 (92%) had IgE antibodies directed at Aubergine (14).
Anaphylaxis to Aubergine in a Latex-allergic 27-year-old female doctor was reported. She experienced generalised itching, dyspnoea, dizziness, vomiting, nausea, abdominal pain, diarrhoea, and rash over the whole body immediately after eating boiled Eggplant. Skin reactivity to raw and cooked Aubergine was detected. IgE antibodies to raw and cooked Aubergine were found, and 1 protein demonstrated a degree of cross-reactivity with a Latex protein (7).
Allergy to Aubergine pollen has been described. Immediate IgE-mediated hypersensitivity reactions (rhinorrhoea and asthma) were described in a 43-year-old man. He presented with rhinoconjunctivitis and a dry cough when working in a greenhouse where Eggplants were cultivated. SPT to Eggplant fruit was negative, but SPT and conjunctival challenge with extract from the flower petals and pollen was positive (16). Similarly, occupational allergy to the plant pollen in 2 commercial gardeners was reported (17).
Contact dermatitis due to Eggplant has been reported (15).
Contact dermatitis was reported in a 28-year-old woman. She had a 3-month history of bilateral hand eczema following home cultivation of Eggplants, Roses and Tomatoes. A patch test to chopped Eggplant leaves was positive. A delayed-type hypersensitivity reaction was suggested (18).
Aubergine is high in histamine, which may result in histamine reactions in susceptible individuals (19).
Aubergine contains the alkaloid alpha-solanine, which is a human plasma cholinesterase inhibitor (20).
Compiled by Dr Harris Steinman, email@example.com
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