Sci­en­tists sniff out an­swer to ‘as­para­gus pee’ mystery

Kuwait Times - - HEALTH & SCIENCE -

Sci­en­tists have sniffed out the rea­son why some peo­ple think their pee has a pun­gent smell af­ter eat­ing as­para­gus while oth­ers do not-it is all down to genes. French nov­el­ist Mar­cel Proust once fan­ci­fully de­scribed the smell as “trans­form­ing my hum­ble cham­ber pot into a bowl of aro­matic per­fume” but it seems he was in the mi­nor­ity as three in five peo­ple are un­able to even de­tect the odor, ac­cord­ing to a study pub­lished yes­ter­day.

From data on 6,909 par­tic­i­pants, 58 per­cent of men and 61.5 per­cent of women had as­para­gus anos­mia, or the in­abil­ity to de­tect the smell, ac­cord­ing to the re­sults in the BMJ med­i­cal jour­nal’s Christ­mas edi­tion, tra­di­tion­ally re­served for stud­ies that are quirky but sci­en­tif­i­cally sound. Among this ma­jor­ity, re­searchers from the Har­vard School of Pub­lic Health found 871 ge­netic cod­ing vari­ants, or SNPs, on genes as­so­ci­ated with smell-sug­gest­ing the in­abil­ity is in­her­ited.

Pro­fes­sion­als have long de­bated the cause of the pun­gent aroma that only some peo­ple de­tect in their urine a few hours af­ter eat­ing the veg­etable. Does the dif­fer­ence arise be­cause some peo­ple do not pro­duce “as­para­gus pee”, or be­cause they are sim­ply un­able to smell it? The new re­search goes some way to­wards an­swer­ing the ques­tion. “This study was con­ceived dur­ing a sci­en­tific meet­ing at­tended by sev­eral of the coau­thors in bu­colic Swe­den, where it be­came ap­par­ent that some of us were un­able to de­tect any un­usual odor in our urine af­ter con­sum­ing new spring as­para­gus,” wrote the team.

They went in search of ex­ist­ing stud­ies on the phe­nom­e­non, and found two USbased projects in which par­tic­i­pants were asked about “as­para­gus pee” in a broader health ques­tion­naire in 2010. Us­ing that data for their own anal­y­sis, the team clas­si­fied “as­para­gus smellers” as peo­ple who “strongly agreed” that they dis­charged a dis­tinc­tive odor af­ter eat­ing as­para­gus. The rest were listed as suf­fer­ing from as­para­gus anos­mia. The team called their study: “Sniff­ing out sig­nif­i­cant ‘Pee val­ues’: genome wide as­so­ci­a­tion study of as­para­gus anos­mia”-a play on the term “P value” used to de­note sta­tis­ti­cal sig­nif­i­cance in sci­en­tific stud­ies. With one ques­tion closer to be­ing an­swered, many still re­main, said the au­thors.

If as­para­gus is packed so full of nu­tri­ents, why would it make some peo­ple give off a smell that may put them off ever eat­ing it again? What drove the evo­lu­tion­ary se­lec­tion that caused some to lack the as­para­gus-smelling gene vari­ants? “And, will sci­en­tists take the re­sults of our study and ap­ply gene edit­ing tech­niques to con­vert smellers to non-smellers?” asked the team. More re­search is needed, they said, “be­fore con­sid­er­ing tar­geted ther­a­pies to help anos­mic peo­ple dis­cover what they are miss­ing”. —AFP

WASH­ING­TON: This file photo taken on Au­gust 6, 2013 shows as­para­gus dis­played for sale at East­ern Mar­ket in Wash­ing­ton, DC. —AFP

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