f328 Fig

Allergens within Food of Plant Origin

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  • Latin name: Ficus carica
  • Family: Moraceae
  • Common names: Fig, Common Fig, Edible Fig
Food
A food, which may result in allergy symptoms in sensitised individuals.

Allergen Exposure

Geographical distribution
The Fig tree is believed to be indigenous to Western Asia and to have been distributed by man throughout the Mediterranean area. It has been cultivated for thousands of years, remnants of Figs having been found in excavations of Neolithic sites dating back to at least 5,000 B.C. European types were eventually taken to China, Japan, India, South Africa, Australia, and North and South America. Some members of the Fig family are ornamental plants and some produce rubber. Over 700 varieties of Fig are in existence.
 
The fruit (usually pear-shaped and up to 5cm in diameter) is actually a swollen flower stalk; female flowers are borne on the inside of a fleshy structure called a receptacle, which expands greatly as the fruit matures. In some varieties, a female Fig wasp crawls through the ostiole (a small hole at the end of the Fig) to pollinate the flowers. Some varieties can bear fruit without pollination.
Fermentation of the fruit can occur if there is too much rain during maturation; rain seeps inside fruit.
 
Environment
The tree grows among rocks and in woods and scrub, or in cultivated groves. In warm, humid climates, Figs are generally eaten fresh and raw without peeling. Peeled or unpeeled, fresh, canned or dried, the fruits may be stewed or cooked in various ways, as in pies, puddings, cakes, bread or other bakery products, or added to ice cream mix. The fruits are sometimes preserved in sugar syrup or prepared as jam, marmalade, or paste. In Europe, western Asia, northern Africa and California, commercial canning and drying of Figs are industries of great importance. Figs have been roasted and ground as a coffee substitute. In Mediterranean countries, low-grade Figs are converted into alcohol, which is sometimes used as a flavoring for liqueurs and tobacco. The seed yields an edible oil that can also be a lubricant. The leaves can be an animal fodder. The latex is dried and powdered for coagulating plant and animal milk. From it can be isolated the protein-digesting enzyme ficin, which is used for tenderising meat, rendering fat, and clarifying beverages.
 
The latex is widely applied on warts, corns, skin ulcers, insect bites, and piles, and taken as a purgative and vermifuge, but with considerable risk. (See under Other Reactions.) In Latin America, Figs are much employed as folk remedies. A decoction of the fruits is gargled to relieve sore throat and diseases of the chest; Figs boiled in milk are packed against swollen gums; the fruits are often used as poultices on tumors and other abnormal growths. The unripe green fruits are cooked with other foods as a galactogogue and tonic. A leaf decoction is taken as a remedy for stomach complaints, diabetes and calcifications in the kidneys and liver, and is used as a steam bath for swollen piles. The young branches are also a pectoral remedy. Fresh and dried Figs have long been appreciated for their laxative action.
 
Unexpected exposure
See under Environment. Also, some members of this tree family produce rubber. Fig wood, though of low quality, may be used for hoops, garlands, emery boards, etc.
 
In southern France, there is some use of Fig leaves as a source of perfume material called "Fig-leaf absolute"—a dark-green to brownish-green, semi-solid mass or thick liquid of herbaceous-woody-mossy odor, employed in creating woodland scents.
 
Allergens
No allergens from this plant have yet been characterised.
 
Potential Cross-Reactivity
An extensive cross-reactivity among the different individual species of the genus could be expected, but this has not been fully investigated to date (1). In a Fig-allergic individual, detection of serum-specific IgE to Weeping Fig tree (F. benjamina) indicated sensitisation to Weeping Fig. Further investigation revealed that these 2 species of Ficus share some allergens (2). However, in a patient with asthma and conjunctivitis caused by an immediate-type allergy to Weeping Fig, who was shown to have serum-specific IgE to Fig, the patient tolerated Fig in an oral provocation test. Sensitisation to latex protein, a possible cross-reaction allergen (see below) was not found in this study (3).
 
Numerous studies have now reported and confirmed cross-sensitization between Fig, Weeping Fig, and Natural Rubber Latex (4). Cross-reacting IgE antibodies have been demonstrated to Latex, Papaya, Avocado, Banana, Chestnut, Passion fruit, Fig, Melon, Mango, Kiwi, Pineapple, Peach, and Tomato. Fruit-specific IgE antibodies were detected only in 32.1% of the 136 patients investigated (5).
 
Hypersensitivity to Weeping Fig latex may cause IgE-mediated respiratory allergy. In this report, the authors conclude that an allergic association of allergy between Fig and Papain is likely due to the existence of cross-reactive allergen structures (6).

Clinical Experience

IgE-mediated reactions
Fig may uncommonly induce symptoms of food allergy in sensitised individuals. Symptoms include pruritis, generalised urticaria, facial angioedema, asthma, gastrointestinal symptoms and anaphylaxis (2, 7-8).
 
Anaphylaxis that occurred very shortly after ingestion of a fresh Fig has been reported. Skin-specific IgE performed with fresh Fig extract was positive, and serum-specific IgE to Fig was found (2, 7).
 
A multifood allergy was described in a 4-year-old child, who had a skin-specific IgE reaction resulting in a 4mm wheal, and serum-specific IgE to Fig (8).
 
Other reactions
The latex of the unripe fruits and of any part of the tree may be severely irritating to the skin and eyes if not removed promptly. It is an occupational hazard not only to Fig harvesters and packers but also to workers in food industries, and to those who employ the latex to treat skin diseases. In tropical America, the latex was an ingredient in some of the early commercial detergents for household use but was abandoned after many reports of irritated or inflamed hands in housewives.
 
Contact with sap from Fig leaves and stems can result in contact dermatitis, phototoxicity or phytophotodermatitis (9).
 
Phytophotodermatitis is an acute skin reaction that may be easily confused with other causes of contact dermatitis. It is characterised by sunburn, blisters, and/or hyperpigmentation. The reaction takes place when certain plant substances known as psoralens, after being activated by ultraviolet light from the sun, come in contact with the skin (10-11). Psoralen and bergapten appear to be the only significant photoactive compounds in Fig, and are present in appreciable quantities in the leaf and shoot sap but are not detected in the fruit or its sap. Lower concentrations of both compounds are present in autumn compared to spring and summer. The higher content of both photoactive compounds in spring and summer is partly responsible for the increased incidence of Fig dermatitis during these seasons (12).

Compiled by Dr Harris Steinman, harris@zingsolutions.com

References:

    1. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09
    2. Dechamp C, Bessot JC, Pauli G, Deviller P. First report of anaphylactic reaction after fig (Ficus carica) ingestion. Allergy 1995;50(6):514-6
    3. Brehler R, Theissen U. Ficus benjamina allergy. [German] Hautarzt 1996;47(10):780-2
    4. Brehler R, Abrams E, Sedlmayr S. Cross-reactivity between Ficus benjamina (weeping fig) and natural rubber latex. Allergy 1998;53(4):402-6
    5. Brehler R, Theissen U, Mohr C, Luger T. "Latex-fruit syndrome": frequency of cross-reacting IgE antibodies. Allergy 1997;52(4):404-10
    6. Diez-Gomez ML, Quirce S, Aragoneses E, Cuevas M. Asthma caused by Ficus benjamina latex: evidence of cross-reactivity with fig fruit and papain. Ann Allergy Asthma Immunol 1998;80(1):24-30
    7. Gandolfo M, Baeza M, De Barrio M. Anaphylaxis after eating figs. Allergy 2001;56(5):462-3
    8. Pajno GB, Passalacqua G, La Grutta S, Vita D, Feliciotto R, Parmiani S, Barberio G. True multifood allergy in a 4-year-old child: a case study. Allergol Immunopathol (Madr) 2002;30(6):338-41
    9. McGovern TW. The fig--Ficus carica L. Cutis 2002;69(5):339-40
    10. Watemberg N, Urkin Y, Witztum A. Phytophotodermatitis due to figs. Cutis 1991;48(2):151-2
    11. Lembo G, Lo Presti M, Balato N. Phytophotodermatitis due to ficus carica. Photodermatol 1985;2(2):119-20
    12. Zaynoun ST, Aftimos BG, Abi Ali L, Tenekjian KK, Khalidi U, Kurban AK. Ficus carica; isolation and quantification of the photoactive components. Contact Dermatitis 1984;11(1):21-5

2004