Large numbers of children are developing severe allergic reactions to kiwi fruit, scientists have found.
In the largest detailed study of its kind, Southampton University researchers have revealed a sharp rise in cases in recent years, particularly among those under 16.
The popularity of the vitamin C-rich fruit has soared since it made its debut in the UK in the late 1960s. Britons now consume more than 31,000 tonnes of the fruit each year, and a recent poll found that one in ten children said the kiwi was their favourite fruit.
For the great majority of people, eating the fruit causes no problem.
But Jane Lucas, a paediatrician and clinical research fellow, and her team at Southampton, found that among the growing minority that has developed an allergy children under six years old are especially likely to react badly.
"For some reason, children seem to be having a more severe reaction," she said.
The researchers worked with 3 subjects who suspected they were allergic to kiwi fruit. All of them completed a questionnaire, and 45 underwent a series of medical tests to deduce how each person reacted.
One in five suffered severe problems, including vomiting, wheezing and collapse in their first allergic reaction.
Severe symptoms were significantly more likely to occur in young children - 40 per cent of cases - than in adults, a pattern not found with other food allergies such as those in reaction to milk or nuts.
Three-quarters of under-sixes reacted on their first exposure to the fruit.
The youngest subject in the study was a four-month-old baby who had previously required resuscitation after suffering a severe anaphylactic reaction.
The Southampton scientists believe the rise in cases may be due to a combination of greater consumption of the fruit and a general increase in the incidence of food allergy.
Many participants in the study reported having other allergies. Almost all the under-sixes, 90 per cent, had been treated for asthma, eczema or hay fever, and 60 per cent reported peanut allergy.
Dr Lucas said that although kiwi fruit allergy affected less than 1 per cent of the population, more awareness of it was needed.
Her team will now look at how proteins in kiwi fruit prompt the abnormal immune responses that cause allergy symptoms.
The study, which was funded by the Food Standards Agency, will be published in the journal Clinical and Experimental Allergy .