Route Of Exposure

his plant is native (though in different types) to temperate regions of both Europe and North America. Technically, raspberries are those brambles in which the small, knobby, thimble-shaped fruit separates readily from the core or receptacle – unlike the similar-looking blackberry, in which the fruit is firmly attached to the receptacle. Raspberries are generally thought to be bright red only, but in reality can also be dark blue, yellow or white.

The brambles grow wild in neglected land, hedgerows and woodland edges in many regions of the world; they are also cultivated, but not on the scale of many other fruits, because the inputs per volume are high enough to make them a luxury food.

Delicious when eaten out of hand, the fruit is also used in pies, syrups, flavourings, jams, jellies and other preserves. A herb tea is made from the dried leaves. The shoots and roots are also edible. Raspberries are rich in phenolic phytochemicals.

The leaves and roots are said to be anti-inflammatory, astringent, decongestant, ophthalmic, oxytocic and stimulant. Teas from the leaves and roots are often taken for gynaecological problems. Externally, the tea is used as a gargle to treat tonsillitis and mouth inflammations, and as a soothing poultice for several external ailments.

A purple to dull blue dye is obtained from the fruit. A fibre obtained from the stems is used in making paper.

Clinical Relevance

Allergen Description

Besides the allergens isolated and/or characterised, raspberry also appears to contain high-molecular-weight proteins which appear to be allergenic.

The following allergens have been characterised:

A chitinase and a cyclophilin have also been isolated.

Detecting Rub i 1 using orthodox assays has been problematic, and may indicate low levels of this allergen in raspberry. The difficulty may also be due to the low sensitivity of alkaline phosphatase western blotting, or to reduced cross-reactivity. The characterisation of this allergen required PCR methods, among others.

A raspberry chitinase has been isolated and shown to react with more than 80% of raspberry-allergic patient sera tested. It has a high sequence homology with class III chitinases. The presence of cross-reacting carbohydrate determinants (CCDs) has been shown in raspberry chitinase.

Potential Cross Reactivity

Extensive cross-reactivity between the different individual species of the family could be expected, and has been documented between various members (e.g. apricot and peach). Similarly, cross-reactivity between a number of berries belonging to the same genus could be expected, but has not been fully explored. Inhibition studies have demonstrated cross-reactivity between currant and raspberry; but in this instance, the patient evaluated – who was allergic to red- and blackcurrant, and peach, apricot, and nectarine – was able to tolerate raspberry, plum, apple, and pear.

Members of the genus Rubus include:

Raspberry – R. idaeus Black raspberry/Thimbleberry – R. occidentalis Cloudberry – R. chamaemorus L. Dewberry – R. caesius Salmon berry – R. spectabilis Blackberry Rf211- R. fruticosus Caneberry – R. laciniatus Marionberry – R. ursinus Loganberry – R. Loganobaccus Boysenberry – R. ursinus x idaeus

Due to Rub i 1 (a Bet v 1 homologue) and Rub i 3 (a lipid transfer protein), cross-reactivity may occur between raspberry and other fruit or vegetables containing these panallergens. Raspberry cyclophilin is homologous to Bet v 7 and may result in cross-reactivity with other cyclophilin-containing foods. Raspberry chitinase may result in cross-reactivity with other chitinase-containing plants.

Clinical Experience

IgE-mediated reactions

Anecdotal evidence suggests that raspberry may induce symptoms of food allergy in sensitised individuals; however, few studies have been reported to date. It is possible that the allergy occurs more frequently than has been reported.

Food-dependent, exercise-induced anaphylaxis (FDEIA) ­– where anaphylactic symptoms appeared not only after postprandial exercise, but also when the food allergen was ingested immediately after prolonged exercise – has been described in a 27-year-old female. In a period of over 12 years she experienced five incidents of FDEIA following ingestion of different fruits: plum, grape, cranberry, peach, blackberry and raspberry. In some episodes the fruits were eaten together, therefore the precise identification of the culprit food was uncertain. The patient experienced two typical episodes of FDEIA; the first occurred after 30 minutes of intensive walking, preceded by eating blackberry. Symptoms included generalised urticaria, facial angioedema, nausea, vomiting and weakness. The second was precipitated 2 years later by ingestion of raspberry, and prolonged physical exercise started about 3 hours later. After 1 hour of dancing she developed anaphylactic symptoms which involved disseminated urticaria accompanied by facial angioedema and nausea. Three unusual episodes of FDEIA were also described. The first, attributed to raspberry, occurred immediately after discontinuation of prolonged exercise lasting 2 hours, when raspberry was ingested. About 20 minutes later she experienced generalised urticaria accompanied by angioedema localised on the face and upper limbs, vomiting and diarrhoea. Skin-prick tests were positive to peach, raspberry, cranberry, nectarine, blackberry and black grape. Total serum IgE was 119 kU/L. An exercise challenge after ingestion of food allergens was not performed.

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. Questionnaires concerning 86 different foods were administered to food-allergic individuals. The foods most often reported as eliciting symptoms in Russia, Estonia, and Lithuania were citrus fruits, chocolate, honey, apple, hazelnut, strawberry, fish, tomato, egg, and milk; which differed from the situation in Sweden and Denmark, where birch pollen-related foods, such as nuts, apple, pear, kiwi, stone fruits, and carrot were the most common reported culprits. The most common symptoms reported were oral allergy syndrome and urticaria. Birch pollen-related foods dominated as reported allergens in Scandinavia, whereas some mugwort-related foods were apparently of more importance in Russia and the Baltic States. Among 1 139 individuals, raspberry was the 32nd-most-reported food, resulting in adverse effects in 16%.

Occupational asthma due to the inhalation of raspberry powder has occurred. A 35-year-old woman complained of hay fever symptoms, wheezing, and shortness of breath, in association with coating a chewing gum with raspberry powder. A 9mm prick test result positive for raspberry powder was seen, and a radioallergosorbent test for raspberry was positive (0.84 kUA/L). Her symptoms disappeared after she was moved to another part of the factory.

Other reactions

Food poisoning affected more than 200 people in the region of Quebec City, Canada, after they ate raspberries imported from Bosnia. Viral studies indicated a virus of the Calicivirus family.

In April 1988, an outbreak of gastroenteritis occurred among employees in a large company in Helsinki, Finland. The research data suggest that the primary source of the outbreak was imported frozen raspberries contaminated by calicivirus.

An outbreak of 24 cases of hepatitis A in Aberdeen, Scotland, was traced to a large hotel. Studies implicated raspberry mousse, prepared from frozen raspberries. The raspberries were probably contaminated at the time of picking.

An outbreak of cyclosporiasis occurred in guests at a wedding reception in Philadelphia, Pennsylvania. In a retrospective cohort study, 54 (68.4%) of the 79 interviewed guests and members of the wedding party met the case definition. The wedding cake had a cream filling that included raspberries.