Scientists are sniffing out the reason why some people claim their pee smells abnormal after eating asparagus, while others don’t. It turns out it’s a simple case of genetics.
“Transforming my humble chamber pot into a bowl of aromatic perfume,” was how French novelist Marcel Proust once described his unique scent. He must’ve been the minority, as three in five people can’t even detect an odour in their pee, according to a study published in the BMJ medical journal’s Christmas edition.
The study, involving 6,909 participants, found 58% of men and 61.5% of women respectively, couldn’t detect any smell, or ‘asparagus anosmia’. From these majority figures, the Harvard School of Public Health found 871 genetic coding variants on genes associated with smell. This suggests that inability to smell is an inherited, genetic trait.
If you can believe it, scientists have long argued the cause of the distinct aroma that only some people notice upon urination after eating asparagus.
This begs the question, however: is the difference simply that some people don’t produce ‘asparagus pee’, or they’re just unable to detect it?
“This study was conceived during a scientific meeting attended by several of the co-authors in bucolic Sweden, where it became apparent that some of us were unable to detect any unusual odour in our urine after consuming new spring asparagus,” the research team wrote.
The team took two existing studies conducted in the States for their analysis, classifying ‘asparagus smellers’ as people who ‘strongly agreed’ that a distinct odour comes from eating asparagus. The rest of the participants were labeled with asparagus anosmia.
But as the researchers get closer to answers for their questions, many remain.
For instance, if asparagus is so rich in nutrients, why does it give off a smell that would dissuade people from eating it again? What caused the evolutionary selection that resulted in a lack of the asparagus-smelling gene variants?
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“And, will scientists take the results of our study and apply gene editing techniques to convert smellers to non-smellers?” asked the team.
They went on to say that more research is required, “before considering targeted therapies to help anosmic people discover what they are missing”.
Hopefully they mean the nutrition of asparagus, and not its aroma.