Red currant
Route Of Exposure
The red currant is a member of the genus Ribes in the gooseberry family, Grossulariaceae. It is native to parts of western Europe (Belgium, France, Germany, the Netherlands, northern Italy, and northern Spain). There are many species of currants, the most common ones being red currant and black currant. They come from a deciduous shrub, normally growing 1 to 1.5 m tall, occasionally 2 m, with 5-lobed leaves arranged spirally on the stems. The flowers are yellow-green and inconspicuous, appearing in pendulous 4 to 8 cm racemes and maturing into bright-red translucent edible berries about 8 to 12 mm in diameter, 3 to 10 berries on each raceme.
Currants are sometimes cultivated but often wild, and are found in many regions of the Northern Hemisphere. The red currant is similar to the black currant (or blackcurrant) but differs mainly in colour, being bright red or white. Confusingly, a small, seedless raisin is also called a ‘currant’.
With its pleasant acid flavour, the fruit can be eaten out of hand but is more often cooked in pies, jams, etc. It is a good source of vitamin C and potassium.
The fruit is said to be depurative, digestive, diuretic, laxative, refrigerant and sialagogue. It is used cosmetically in face-masks.
The fresh leaves contain the toxin hydrogen cyanide, though details of quantities are not known. In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion (and may be of benefit in the treatment of cancer). In excess, however, it can cause respiratory failure and even death.
A yellow dye is obtained from the leaves, and a black dye from the fruit.
Clinical Relevance
IgE-mediated reactions
Anecdotal evidence suggests that red currant may, in rare instances, induce symptoms of food allergy in sensitised individuals; however, few studies have been reported to date.
A 19-year-old woman with a history of urticaria-angioedema in childhood due to sunflower seed and peanut developed malaise, palpebral and genital angioedema, erythema on her face and neck, systemic hives, pruritus, and dysphonia immediately after eating duck meat with red currant sauce. Total IgE was 138 kUA/L. Skin-prick tests were positive for a range of allergens, and prick-by-prick testing was positive to red currant and plum. Specific IgE (kUA/L) was detected to Artemisia vulgaris (1.54); Chenopodium album (0.38); Platanus acerifolia (0.59); strawberry (0.67); apple (3.63); peach (7.71); plum (0.70); onion (0.45); peanut (1.13); chestnut (1.24); walnut (2.82); and pistachio (0.38). Specific IgE to peach Pru p 3 was 17.03 kUA/L. IgE to red currant was positive by enzyme-linked immunosorbent assay; and a single 14 kDa band, identified as a lipid transfer protein, was seen on immunoblot.
The aim of a study conducted at 17 clinics in 15 European cities was to describe the differences between some northern countries regarding self-reported hypersensitivity symptoms from foods. Patients with a history of food hypersensitivity were asked to fill out a questionnaire in which 86 different foodstuffs were listed. ‘Slight symptoms’ were most common with (among others) red currant, which was the 49th-most-reported food resulting in adverse effects, affecting 9.2% of 1 139 individuals.
In a rare case of anaphylaxis, a 47-year-old woman presented with generalised urticaria, dysphagia, dyspnoea, pruritis of the palms and soles, hyptonia, and tachycardia, 2.5 hours after eating red currants. A month later, she developed generalised urticaria after eating black-currant jam. Skin-specific IgE (prick-to-prick) was positive to red currant and black currant. Serum IgE was absent for both.
An earlier report of anaphylaxis to red currant also lacked detectable IgE levels, but exhibited specific IgA and IgM antibodies instead.
A study reported on a 50-year-old woman with allergy to grass pollen and oral allergy syndrome involving several fruits. She presented with pruritus and pharyngeal occupation with dysphagia, while eating fresh red and black currant jam. She reported similar episodes with peach, apricot, and nectarine (jam, juice, and fresh). She tolerated other fruits of the Rosaceae family (i.e. raspberry, plum, apple, and pear). Skin prick-to-prick tests with fresh red and black currants were negative, and positive to peach. Specific IgE to red currant was 5.7 KU/L, and 2.92 KU/L for peach.
Cross-Reactivity
Extensive cross-reactivity among the different individual species of the genus could be expected, but this possibility has not been explored. The following are of particular interest:
Gooseberry/English gooseberry – R. grossularia
Blackcurrant/black currant – R. nigrum
A lipid transfer protein (LTP) has been identified which may result in cross-reactivity with other LTP-containing foods.
References
- Pérez-Ezquerra PR, de la Gaspar MV, de Fernández MB, Flores VT, Alvarez-Santullano AV, de Ocáriz ML. Currant allergy and the Rosaceae-grass pollen allergy syndrome: a case report. Ann Allergy Asthma Immunol 2007;98(5):480-2.
- Tomás M, Alvarez-Perea A, Ledesma A, Baeza ML, de Barrio M. Allergy to red currant: immunoglobulin E-mediated hypersensitivity to lipid transport proteins (Pru p 3). J Investig Allergol Clin Immunol 2012;22(2):140-1.
- Kühl P, Kalveram CM, Gall H. Anaphylaxie auf rote Johannisbeere. Allergo J. 1997;7:17-9.
- Zollner TM, Schmidt P, Kalveram CM, Emman AC, Boehncke WH. Anaphylaxis to red currants. Allergy 2000;55(5):511.
- Eriksson NE, Möller 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.
- Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09.