f318 Jack fruit

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The genus Artocarpus contains A. altilis (breadfruit) and A. heterophyllus (Jack fruit). The Jack fruit is a tropical fruit which belongs to the Moraceae (mulberry) family and is cultivated at low elevations throughout South-East Asia. It is grown to a limited extent in Queensland Australia, Mauritius, the Pacific Islands, Brazil and Surinam. In Africa, it is often planted in Kenya, Uganda and Tanzania.

This huge relative of the breadfruit can weigh up to 50 kg. It is spiny and oval or oblong-shaped.

The tree is cultivated in some places and wild in others. The fruit is an excellent example of a food prized in some areas of the world and allowed to go to waste in others. Jack fruit is little used in the West (and tends to be available only in canned form) because of the copious latex and the foul odour of the raw fruit. The fruit is eaten raw, boiled or fried; its seeds are roasted like chestnuts. It may be made into ice cream, chutney, jam, liqueur, pulp, custard, jelly, nectar, powder or concentrate, paste, ‘leather’ (or ‘papad’), or even a potato-like chip. It may also be pickled, canned or frozen. It is often included in curried dishes. The roasted, dried seeds are ground to make flour, which is blended with wheat flour for baking. Tender Jack fruit leaves and young male flower clusters may be cooked and served as vegetables. In India, the leaves are used as food wrappers in cooking, and they are also fastened together for use as plates.

The Chinese consider Jack fruit pulp and seeds to be tonic and cooling and recommend them as a hangover cure. The seeds and leaves may be used as an herbal remedy. The dried latex yields artostenone, convertible to artosterone, a compound with marked androgenic action. Mixed with vinegar, the latex is said to promote healing of abscesses, snakebite and glandular swellings. The root and wood may also be used as a herbal remedy. The pith is said to induce abortion.

The seeds of Jack fruit contain 2 lectins: jacalin and artocarpin. Jacalin, a 66 kDa protein, is one of very few proteins known to bind T-antigen, and thus has great potential diagnostic value. T-antigen is expressed in more than 85% of human carcinomas.

Jack fruit extract significantly lowered the fasting blood glucose level and markedly improved glucose tolerance in Sprague-Dawley rats. The maximum effect was not observed, even at +5 hrs. The hypoglycaemic activity was better than that of tolbutamide.(1)  The significance of this finding for humans has not been evaluated yet.

The inedible portions of the fruit yield jelly, pectin and a syrup used for tobacco curing. In some areas, the fruit and the leaves are fed to cattle. The latex serves as birdlime, and as household cement and caulk. The mahogany-like wood has a variety of uses. The sawdust yields a rich yellow dye commonly used for dyeing silk and cotton. The bark is occasionally made into cordage or cloth.

Anecdotal evidence suggests that Jack fruit can occasionally induce symptoms of food allergy in sensitized individuals; however, few studies have been reported to date. (2, 3) Increased consumption of this fruit will result in a rise in allergic reactions. (2) Ingestion of jackfruit resulting in anaphylaxis has been reported in 3 individuals. (4, 5).

A 30-year-old Filipino man with pollen allergy developed symptoms of oral allergy syndrome (OAS) after eating raw apple, raw peach, raw celery, and Jack fruit. Despite evidence of multiple sensitization in skin-prick tests and serum IgE tests for birch, grass and mugwort pollen, related fruits and vegetables, and Jack fruit, in RAST inhibition studies neither rBet v 1 nor rBet v 2 (profilin) – the well-known cross-reacting allergenic components in OAS – could inhibit the specific IgE response to Jack fruit. Whether the reaction to Jack fruit is specific or whether other pollen-related cross-reacting allergenic components exist could not be elucidated, and the authors suggested that this should be further investigated. (6)

Two Jack fruit-allergic patients are described. Both patients claimed they had never eaten Jack fruit before. A 31-year-old man with a history of hay fever in the birch pollen season increasingly reported episodes of OA symptoms after eating apple, hazelnut or peanut. He developed oral allergy symptoms within 5 minutes of eating a very small piece of fresh Jack fruit. Within 10 minutes, that had progressed to hoarseness, swelling of the throat and dyspnoea. A 27-year-old female with hay fever in the birch and grass pollen season reported increased oral allergy-like symptoms after eating apple, hazelnut and peanut. She experienced oral allergy symptoms and abdominal cramps within 5 minutes of eating a small piece of fresh Jack fruit. Double-blind placebo-controlled challenges confirmed the diagnosis in both patients. Skin-prick tests were positive, and serum-specific IgE to Jack fruit was 5.9 and 0.8 IU/ml for the 2 patients. Sensitization was demonstrated to a Bet v 1-related allergen. Five patients with concomitant birch pollen and fruit allergy who underwent an oral challenge with Jack fruit developed oral allergy, confirming the presence of a panallergen and suggesting that individuals with both birch pollen and fruit allergy should avoid this fruit. (2)

Adverse reactions to lectins present in the fruit are possible, including the agglutination of red blood cells in humans and animals.

No allergens from this plant have yet been characterized.

A 17 kDa protein with characteristics of Bet v 1 – i.e. a Bet v 1 homologue – has been isolated. (2). Both species of Artocarpus (Artocarpus altilis [breadfruit] and Artocarpus heterophyllus [Jack fruit]) contain lectins, which are very similar to each other(3).

Cross-reactivity

Cross-reactivity among the different individual species of the genus could be expected. (6)

To assess whether Jack fruit allergy might be common in patients with birch pollen and fruit allergy, 5 birch-pollen and concomitant fruit-allergy patients were orally challenged with Jack fruit. All 5 developed symptoms of oral allergy. The study concludes that Jack fruit contains at least 1 panallergen, which may result in birch pollen-related food allergy. (2)

Last reviewed:April 2022