A study published Wednesday in Nature Microbiology identified the enzyme responsible for the characteristic yellow hue of urine. The discovery sheds light on a question that has puzzled scientists for more than a century, CBS News reported.
“It’s remarkable that an everyday biological phenomenon has remained unexplained for so long, and our team is excited to be able to explain it,” said Brantley Hall, an assistant professor in the University of Maryland’s Department of Cell Biology and Molecular Genetics.
Urine is formed after a combination of electrolytes and waste that the human kidneys filter out of the blood. More than a century ago, scientists discovered that urobilin was the yellow pigment in urine, but they didn’t know how it was made.
Researchers have reported that the color of urine is linked to the body’s red blood cells (RBCs).
Our red blood cells, like worn tires, eventually break down. When they do, they leave behind a bright orange stain called bilirubin. This bilirubin will explore your bowels, either ride with the poop or stick around for another loop.
But guess what? The tiny bugs in your gut, like microscopic chefs, can take this orange goo and turn it into a variety of things, including the yellow stuff that gives your pee its sunny color. So the next time you see that yellow in the bowl, remember it’s all thanks to those little chefs working their magic!
“Gut microbes encode the enzyme bilirubin reductase, which converts bilirubin into a colorless byproduct called urobilinogen,” said Hall, lead author of the study. “The urobilinogen then spontaneously breaks down into a molecule called urobilin, which is responsible for the yellow color we all know.”
Before this study, researchers thought that several enzymes were responsible for urine color, the researchers added.
When you’re a hydrated person, your pee should be a clear whisper (but not too much water!), or maybe a pale straw or honey shade. But if you’re stingy with water, it turns into a darker yellow or amber scream. Think of it as your body’s way of saying, “Hey, fill up the tank!”
