Guava Allergy Test
Latin name: Psidium guajava
Source material: Fresh fruit
Common names: Guava, Brazilian guava, Common guava, Guinea guava, Lemon guava, Mountain guava, Purple guava
Guava Allergy Test: Allergen Exposure
Guavas are native to Central and South America but are now cultivated in many countries.
The fruit, which exudes a strong, sweet, musky odour (attributed to carbonyl compounds), may be round, ovoid, or pear-shaped when ripe. It has a thin, light-yellow skin, frequently blushed with pink.
Next to the skin is a layer of somewhat granular flesh of varying colour and flavour. The central pulp is juicy and normally filled with very hard, yellowish seeds.
Raw guavas can be eaten out of hand but are preferred seeded and served sliced, as dessert or in salads. The sweet yellow fruit is eaten fresh; the pulp of the red, sour varieties is used for jelly, juices, etc. More commonly the fruit is cooked, as cooking eliminates the strong odour.
Guavas are used in pies, cakes, puddings, sauces, ice cream, tapioca, juice, syrup, jam, butter, marmalade, chutney, relish, tomato sauce, breakfast cereal, baby food and other products.
The fruit may be canned or frozen, and extracts provide flavourants, pectin for food processing, and vitamin C for enrichment of other foods. Besides supplying vitamin C, guavas are a good source of potassium and fibre.
Guava has long been used as an ingredient in folk medicine around the world. The roots, bark, leaves, shoots, and immature fruits are astringent. They are also thought to be analgesic, emmenagogue, febrifuge, and vermifuge, and are used to treat a variety of ailments both internal and external.
The leaves, bark and young fruit are rich in tannins and other volatile compounds. In Central America the bark is used for tanning hides. The leaves, used with other plant materials, make a black dye for silk, cotton, and matting.
Guava Allergy Test: Allergen Description
No allergens from this plant have yet been characterised.
A 30 kDa allergenic protein, possibly a panallergen, has been detected.
Guava Allergy Test: Potential Cross-Reactivity
Extensive cross-reactivity between the different individual species of the genus could be expected; also frequent cross-reactivity to the different species of the genus Melaleuca, and occasional cross-reactivity to Eucalyptus and other genera of the family Myrtaceae.
In one case, IgE antibodies were found to peach, guava, banana, mandarin and strawberry in a patient experiencing anaphylaxis after eating peach.
Guava Allergy Test: Clinical Experience
Anecdotal evidence suggests that guava can occasionally induce symptoms of food allergy in sensitised individuals; however, no studies have been reported to date.
A survey of 800 patients reporting to the Allergy Unit of the Institute of Child Health, Calcutta, found that of 123 patients tested for sensitisation to guava, 25% were positive.
Allergic contact dermatitis due to guava tea has been reported.
According to Chinese medicinal folklore, guava has been useful in the treatment of diabetes mellitus. A study shows that guava produced a marked hypoglycemic action in mice.