f288 Blueberry

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The name Blueberry is given to several related shrubs, and at least 50 species belong to the same genus as Blueberry. Other similar berries are Cranberry, lingonberry, bilberry and huckleberry (this last name is sometimes applied to Blueberry, mistakenly). The round, smooth-skinned, blue-black berries are juicy and sweet and only about 10 mm in diameter. The Highbush variety of bush can grow up to 5 m in height; the hardier Lowbush blueberry plants can reach 1 m high. Blueberries are found wild and are cultivated in temperate to cold climates, especially in Canada, New England, Great Britain and New Zealand, but they are relatively uncommon and expensive, and so are a rarity in most diets.

Blueberries often grow wild on heaths, the sunny edges of woods and other brushy environments, but most commercially available Blueberries are cultivated. They are usually eaten as a raw snack or in baked goods, jams, pancakes, or salads. They can be dried and used like currants. A tea is made from the leaves.

While the fresh fruit has a slightly laxative effect upon the body, when dried it is astringent and is commonly used in the treatment of diarrhea, cystitis, etc. The dried fruit is also antibacterial. The skin of the fruits contains anthocyanin and is specific in the treatment of hemeralopia (day-blindness). The fruit is a rich source of anthocyanosides, which have been shown experimentally to dilate the blood vessels: this makes it a potentially valuable treatment for varicose veins, haemorrhoids and capillary fragility.

A tea made from the dried leaves is strongly astringent, diuretic, tonic, and an antiseptic for the urinary tract. The tea (containing glucoquinones, which reduce the levels of sugar in the blood) is also said to be a remedy for diabetes if taken for a prolonged period. Another report says that the tea can be helpful in pre-diabetic states.
A decoction of the leaves or bark is applied locally in the treatment of ulcerations. A distilled water made from the leaves is used for soothing inflamed or sore eyes.

The closely related lingonberry (V. vitis-idaea L.), Small cranberry (V. microcarpum) and Bigger cranberry (V. oxycoccos L.,) are popular in Nordic countries and Russia, and are used in gravies, and a salad dressing. Cranberry and lingonberry have been increasingly marketed as a natural remedy for recurrent urinary infections (1).

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A green dye is obtained from the leaves and the fruit and is used to colour fabrics. A blue or black dye is obtained from the fruit. This can be used as an ink. Blueberry juice can also be used as an oral contrast agent in upper abdominal magnetic resonance imaging (MRI).

IgE-mediated reactions

Anecdotal evidence suggests that Blueberry can occasionally induce symptoms of food allergy in sensitised individuals; however, no studies have been reported to date. This may be related to the generally low allergenicity of this berry, the small amounts consumed, or the restricted time frame of consumption. Low exposure to certain allergens might be the reason for the limited complaints recorded so far, but with the ongoing promotion of the consumption of small fruits, this situation might change (2).

For example, a 25-year-old woman reported adverse reactions to the close family member lingonberry (V. vitis-idaea). While eating lingonberry jam, she developed itching wheals around her mouth. Symptoms resolved spontaneously. During a second episode, when she again ingested a very small amount of lingonberry jam several days later, she immediately noticed more-intense symptoms, including severe itching on the mouth, tongue and throat, and wheals over the mouth. Symptoms resolved spontaneously within an hour. Skin reactivity testing using a prick-prick method with fresh lingonberry was positive (1).

In a study aimed at characterizing allergens from Raspberry, sera from 8 female patients were assessed. A 25-year-old with periorbital oedema and rhinitis from Lemon and other citrus fruits was described, who was prick-to-prick positive to Peach, Lemon, Sweet Lime, Orange, Banana, Blueberry, Tomato, Grape and Bell pepper (3).

No allergens from this plant have yet been characterised. Blueberry has been shown to contain a lipid transfer protein (2). Very strong reactivity has also been detected to high-molecular-weight proteins (2).

Cross-reactivity

Although none has been documented to date, there may be cross-reactivity with other fruits in the genus Vaccinium, which are erroneously called Cranberries (3). V. vitis-idaea (cowberry, foxberry, mountain cranberry, rock cranberry, lingonberry) is not cultivated but gathered, and is used in Europe, especially in Scandinavia, in food products such as preserves and beverages.

Blueberry has been shown to contain a lipid transfer protein that is cross-reactive with LTPs of a number of foods, in particular stone fruits, e.g., Pru p 3 (Peach), Pru a 3 (Apricot), and Pru av 3 (Cherry) (2). Raspberry also contains an LTP-homologous protein, and LTPs have been identified in, among others, Grape, Chestnut, Hazelnut, Maize, Barley, Asparagus, Carrot and Lettuce (2).

Last Reviewed-  April 2022