Guava
Summary
Food
A food, which may result in allergy symptoms in sensitised individuals.
Allergen
Allergen Description
No allergens from this plant have yet been characterised.
A 30 kDa allergenic protein, possibly a panallergen, has been detected.
Route Of Exposure
Allergen Exposure
Guavas are native to Central and South America but now grow in many countries. Guava was said to be a favourite food of the Incas and Aztecs. The trees are among the most gregarious of fruit trees.
A small tree with spreading branches, the guava is easy to recognise because of its smooth, thin, copper-coloured bark that flakes off, showing the greenish layer beneath. 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.
The guava can be a home fruit tree or be planted in small groves. In many parts of the world, guava runs wild and forms extensive thickets, overrunning pastures, fields and roadsides so vigorously that it can be classed as a noxious weed, subject to eradication. Nevertheless, in some countries wild guava (though underutilised) constitutes the bulk of supply for major industries.
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. There are innumerable recipes for using guavas in pies, cakes, puddings, sauces, ice cream, tapioca, juice, syrup, jam, butter, marmalade, chutney, relish, tomato sauce, breakfast cereal, baby food and other products. Guavas 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 is an important medicinal plant in tropical and subtropical countries, and is widely used 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 wood is used in carpentry, turning, and for engravings and other ornaments, but is not durable when wet. It is good firewood, and also a source of charcoal.
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.
Clinical Relevance
IgE-mediated reactions
Anecdotal evidence suggests that guava can occasionally induce symptoms of food allergy in sensitised individuals; however, no studies have been reported to date.
In an Indian study to evaluate the effect of a specific elimination diet on symptoms, among 24 children aged 3 to 15 years with documented deterioration in control of their perennial asthma, 79% were shown to have specific IgE directed at guava.
A survey of 800 patients (410 male and 390 female) reporting to the Allergy Unit of the Institute of Child Health, Calcutta, found that of 123 patients tested for sensitisation to guava, 31 (25%) were positive.
Allergic contact dermatitis due to guava tea has been reported.
Other reactions
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.
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. Rose-apple and clove are the most closely related members of this family, which includes the bottlebrush tree (Callistemon citrinis), feijoas (Feijoas sellowiana), the eucalyptus tree (Eucalyptus species), the Melaleuca tree (Melaleuca leucadendron), and the Melaleuca tea tree (Melaleuca alternifolia).
IgE antibodies were found to peach, guava, banana, mandarin and strawberry in a patient experiencing anaphylaxis after eating peach. The cross-reactive protein was identified as a 30 kDa protein occurring in all the fruits.
References
- Gutiérrez RM, Mitchell S, Solis RV. Psidium guajava: a review of its traditional uses, phytochemistry and pharmacology. J Ethnopharmacol 2008;117(1):1-27.
- Wadee AA, Boting LA, Rabson AR. Fruit allergy: Demonstration of IgE antibodies to a 30kD protein present in several fruits. J Allergy Clin Immunol 1990;85:801-7.
- Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09.
- Agarkhedkar SR, Bapat HB, Bapat BN. Avoidance of food allergens in childhood asthma. Indian Pediatr. 2005;42(4):362-6.
- Mandal J, Das M, Roy I, Chatterjee S, Barui NC, Gupta-Bhattacharya S. Immediate Hypersensitivity to Common Food Allergens: An Investigation on Food Sensitization in Respiratory Allergic Patients of Calcutta, India. WAO Journal 2009;2(1):9-12.
- Obi M, Miyazaki Y, Yokozeki H, Nishioka K. Allergic contact dermatitis due to guava tea. Contact Dermatitis 2001;44(2):116-7.
- Cheng JT, Yang RS. Hypoglycemic effect of guava juice in mice and human subjects. Am J Chin Med 1983;11(1-4):74-6.