--- title: "Scientists Have Been Studying Your Pee and They Finally Have Answers" description: "Until now, scientists didn't know what exactly made pee yellow — and the answer seems to be situated a bit north of the bladder after all." date: "2024-01-05" modified: "2024-01-05" authors: - name: "Noor Al-Sibai" job_title: "Senior Staff Writer" link: "https://futurism.com/authors/nooralsibai" url: "https://futurism.com/neoscope/scientists-urine-enzyme-yellow" categories: - "Health & Medicine" - "Studies" tags: - "Enzymes" - "gut bacteria" - "red blood cells" - "urine" --- # Scientists Have Been Studying Your Pee and They Finally Have Answers ![Until now, scientists didn't know what exactly made pee yellow — and the answer seems to be situated a bit north of the bladder after all.]() *\Image: Getty / Futurism\* Until now, scientists somehow didn't know exactly what made pee yellow. But that just may have finally changed. In a new study [published in the journal *Nature Microbiology*](), a multidisciplinary group of scientists out of the University of Maryland reported on their findings about a middleman enzyme called bilirubin reductase, which had long evaded researchers as they tried to figure out which precise compounds resulted in urine's distinct yellow hue. To be clear, as [*Healthline* reports](), scientists had known for more than 125 years that on a high level, urine gets its color from the disposal of old red blood cells as they degrade in our livers. But although the process by which urine became yellow was known, the middle-man of compounds couldn't be captured until genome sequencing technology became advanced enough to break down the building blocks of pee. "Our work to find \[bilirubin reductase\] relied on combining experimental screening with genomic analysis, an approach that has only become possible with the isolation of more gut bacterial species and the advancement of genome sequencing technology," UMD cell biologist and molecular geneticist and paper co-author Brantley Hall told *Healthline*. "Unfortunately, gut microbes can be challenging to study," Hall added. "The gut is a low-oxygen environment, and many of the bacteria in our guts can’t survive if too much oxygen is present, making them difficult to grow and perform experiments on in labs. This ultimately meant that only a handful of bacterial species had ever been identified as being able to metabolize bilirubin, limiting the amount of data that was available." After finally being able to isolate gut bacteria long enough, the scientists eventually found that bilirubin reductase, abbreviated as BilR, was the enzyme that took the orange bilirubin gut compound and transformed it into urobilin in the liver. Beyond finding the missing piss link, this discovery could also help scientists and doctors understand and treat jaundice in infants, as well as other conditions related to bilirubin breakdown failure including gallstones and inflammatory bowel disease in adults and, less commonly, other disorders in which [bilirubin builds up so much]() that people become extremely sick, get brain damage, and can even die. At the end of the day, however, it's also extremely exciting that scientists have figured this out at all. "It’s remarkable that an everyday biological phenomenon went unexplained for so long," Hall exclaimed, "and our team is excited to be able to explain it." **More on bodily functions:** [*Guy Who Used Son as a "Blood Boy" Says Elon Musk Will "Fire You and Leave You to Die"*]() ## Author At Futurism, I've often been drawn to unpacking the narratives that underlie technological, scientific and medical progress, with a special interest in areas of conflict and ambiguity that end up setting agendas and steering the fates of both elites and the hoi polloi. I'm a committed generalist, but I often find myself returning to work involving NASA and the private space sector, the effects of AI on media and society, and the mechanics of the pharmaceutical industry, with a specific focus on the spread of GLP-1 drugs like Ozempic and Wegovy. Prior to Futurism, I worked for publications ranging from Media Matters and Truthdig to Raw Story and Bustle. I'm also the author of "Myspace Scene Queens," a 2024 title in Instar Books' acclaimed "Remember the Internet" series. My work at Futurism has been cited by outlets including the New Yorker, Slate, Nieman Lab, the Verge, the MIT Technology Review, the Sunday Times, and the Daily Beast. I grew up in North Carolina, attended the University of North Carolina at Asheville, and now live in Brooklyn, New York. In my free time, I'm an avid reader and music fan; you can probably find me at a local poetry reading, concert, underground rave, or DJ set. I'm the proud parent of an ineffable orange cat named Mee-Mow. ### Author social links [Bluesky]()