Banana allergy triggers surprising

3 minute read

Allergies to birch, latex and melons may predispose some people to banana anaphylaxis, research suggests.

Bananas aren’t common allergens, but the bendy fruit can occasionally trigger anaphylaxis.

Three severe pollen-food allergic reactions to banana have been described in a poster presentation at the Australasian Society of Clinical Immunology and Allergy (ASCIA) conference in Sydney this month.

Researchers said the patients presented to Royal Prince Alfred Hospital in Sydney with severe reactions to uncooked banana, with symptoms including oral and throat pruritis, nausea, wheeze, stridor, hives, dysphagia and presyncope.

All three were middle aged men with histories of oral allergy syndrome. Two were born overseas and two had previous sensitivity to birch pollen.

The researchers, led by Dr Carolyn Wijaya from RPA and the University of Sydney, said banana allergy was associated with tree pollen allergy – often birch – as well as latex allergy and ragweed-melon-banana syndrome, in which patients with an allergy to ragweed are also allergic to members of the gourd family (such as melon, watermelon, zucchini and cucumber) and banana.

Around 2-10% of people with pollen-food allergy syndrome had systemic reactions to triggers such as peanuts, tree nuts, peaches and mustard, but bananas did not commonly cause systemic reactions.

Avoiding the food trigger was common for patients with pollen-food allergy syndrome, and antihistamines could help reduce symptoms, they said.

“[But] not all anaphylaxis presentations should mandate complete avoidance of the food trigger; a thorough review should include differentials such as pollinosis and pollen-food allergy syndrome with appropriate investigations,” the researchers said.

Profilins in foods were sensitive to heat and digestion, so patients could often eat the allergen if it was cooked.

“Our patients who presented with severe allergy symptoms to raw banana have had their diets liberalised and are now able to ingest thoroughly cooked banana in various forms.”

Two-thirds of the patients in the study were prescribed an EpiPen, which the researchers said could be prescribed to patients with “previous systemic reactions, significant throat systems or reactions to cooked foods”.

Oral food challenges with cross-reactive foods and the cooked form of the “culprit food” could be considered for those with a systemic reaction, they said.

But while some patient may improve following allergen immunotherapy to pollen, “results were mixed,” they said.

“Prick-to-prick testing with all components of the fruit may also be helpful, as the peel or seed of the fruit may be a source of allergen.

“Component-resolved diagnostic testing could also help to determine if patients are sensitised to labile or stable food proteins. However, these tests are not currently readily available in Australia.”

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