Nu­tri­tion

As if liv­ing with hay fever isn’t enough, many peo­ple with that con­di­tion also re­act to cer­tain foods.

New Zealand Listener - - CONTENTS - by Jen­nifer Bowden

As if liv­ing with hay fever isn’t enough, many peo­ple with that con­di­tion also re­act to cer­tain foods.

Ques­tion:

I be­come wheezy when peel­ing pota­toes and get a tingly mouth when I eat al­falfa sprouts and macadamia nuts. Ear­lier this year, I ate a hand­ful of un­cooked mung beans and I prac­ti­cally lost my voice. At Auck­land City Hos­pi­tal, I was given adren­a­line to over­come this, and I now carry an adren­a­line pen. My re­ac­tion has been called an oral al­lergy. What are fresh prod­ucts sprayed with to cause this? I’m now care­ful about wash­ing and peel­ing fresh veg­eta­bles.

Oral al­lergy syn­drome (OAS) af­fects about three-quar­ters of hay-fever suf­fer­ers, says al­lergy spe­cial­ist Dr Vin­cent St Aubyn Crump. Crump, the au­thor of Al­ler­gies: New Zealand’s Grow­ing Epi­demic, says the syn­drome is preva­lent in re­gions such as Queen­stown and Gis­borne. The symp­toms of this sec­ondary al­lergy are of­ten mild, so many peo­ple are un­aware they have it and ha­bit­u­ally avoid foods that they re­act to.

Cer­tain fruit, vege­ta­bles, nuts and seeds con­tain pro­teins with a sim­i­lar struc­ture to pol­lens. The im­mune sys­tem of hay-fever suf­fer­ers can con­fuse the two and start re­act­ing to cer­tain food pro­teins, says Crump, a con­sul­tant al­ler­gist at Uni­ver­sity Hos­pi­tal of South Manch­ester. “It’s mainly due to a cross-re­ac­tion with birch pollen, but it’s also seen with grass and weed pollen cross-re­ac­tions.”

Un­like a pri­mary al­lergy, such as that trig­gered by peanuts, which can lead to life-threat­en­ing ana­phy­laxis, OAS is usu­ally lo­calised. “The rea­son is that th­ese al­ler­gens are la­bile and eas­ily de­stroyed by the di­ges­tive en­zymes in the gut.” So af­ter caus­ing symp­toms such as swelling of the lips and/or itch­ing or mild swelling in­side the mouth or throat, the pro­teins

are de­stroyed by the di­ges­tive sys­tem rather than be­ing ab­sorbed into the cir­cu­la­tion as al­ler­gens.

Some peo­ple with the syn­drome re­port nose and eye symp­toms and itchy hands when han­dling raw pota­toes or parsnips. So com­bined with the fact that it rarely causes ana­phy­laxis, or a se­vere re­ac­tion, “oral al­lergy syn­drome” is a bit of a mis­nomer, Crump says. “Pollen food syn­drome is a bet­ter term.”

Com­mon trig­gers are raw fruit and veg­eta­bles, in­clud­ing ap­ples, apri­cots, pears, cher­ries, ki­wifruit, mango, plums, peaches, nec­tarines, toma­toes, car­rots and cel­ery. Other plant foods oc­ca­sion­ally cause the con­di­tion, in­clud­ing raw peas, soy milk, and raw or stir-fried legumes such as bean sprouts.

Cook­ing can de­stroy the al­ler­gic ef­fect of trig­ger foods. “Ap­ples are one of the most com­mon causes. How­ever, peo­ple who get OAS from ap­ples can eat them stewed with­out any symp­toms.”

But in a small num­ber of peo­ple, the syn­drome causes a se­ri­ous ana­phy­lac­tic re­ac­tion. Typ­i­cally, nuts are the trig­ger, says Crump.

“The nuts com­monly as­so­ci­ated with pollen food syn­drome are hazel­nuts, al­monds and wal­nuts. Again, it’s usu­ally raw nuts that cause symp­toms, whereas pro­cessed nuts, such as in choco­late spread Nutella, are tol­er­ated.”

It’s im­por­tant to dis­tin­guish pri­mary nut al­ler­gies un­re­lated to pollen from OAS caused by nuts, he says. “If there is doubt, af­fected peo­ple should be as­sessed by an al­ler­gist, as oc­ca­sion­ally an adren­a­line auto-in­jec­tor is needed.”

For those with OAS, the so­lu­tion is cook­ing fresh pro­duce to de­stroy the al­ler­gens. Of­fend­ing fruit should be stewed. “Even a mi­crowave will do it,” says Crump. Sim­i­larly, trig­ger veg­eta­bles should be cooked.

Peo­ple who re­act to a wide range of foods may re­quire ex­pert guid­ance to man­age the con­di­tion. Re­mov­ing many fruits and veg­eta­bles from the diet could af­fect the in­take of vi­ta­min

C and other im­por­tant mi­cronu­tri­ents.

Com­mon trig­gers are raw fruit and veg­eta­bles, but cook­ing de­stroys the al­ler­gic ef­fect.

Dr Vin­cent St Aubyn Crump: hay-fever suf­fer­ers’ im­mune sys­tems can re­act to cer­tain food pro­teins.

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