All asparagus eaters make funky-smelling pee, but only some can smell it.
You may love asparagus (it’s one of the healthiest spring veggies) and all the good-for-you nutrients it has to offer, but if you’re like some people, you may not love the funky stench it gives off after you pee.
Never smelled something funky in the toilet after eating asparagus? Well, “urine” luck. You likely have what’s called asparagus anosmia, a genetic mutation that hinders your ability to smell asparagus pee compounds.
In a 2016 study, Harvard researchers asked about 7,000 people if they could detect a distinct smell in their urine after eating asparagus. About 40 percent strongly agreed that they could. The other 60 percent said they could not. Researchers found that the people who couldn’t smell the funk shared a combination of at least 871 different genetic alterations that may classify them as being asparagus anosmic.
So what exactly are these asparagus pee compounds that most people can’t detect? These green spears have a compound called asparagusic acid, which when ingested is converted into rotten egg-like chemicals. Once these icky-smelling chemicals leave your body in the form of pee, the change in temperature turns them into vapor which, you guessed it, travels straight up to your nose. Oh joy.
Even though those molecules find their way to all of our nostrils, only those without asparagus anosmia can smell it.
A funky fact? Yes, but it’s not as funky as eau de asparagus pee.
Sniffing out significant “Pee values”: genome wide association study of asparagus anosmia. Boston, MA: Department of Epidemiology, Harvard TH Chan School of Public Health, 2016. (Accessed on June 4, 2018 at https://www.bmj.com/content/355/bmj.i6071)
Asparagusic acid. London, UK: Computational and Systems Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, 2014. (Accessed on June 4, 2018 at https://www.ncbi.nlm.nih.gov/pubmed/24099657)