Although it's common knowledge that urine tends to be a shade of yellow in a healthy person, scientists didn't actually know what caused urine to be that color until recently. According to a study published in scientific journal Nature Microbiology, an enzyme called bilirubin reductase gives urine its yellow color.
Researchers have known for a long time that bilirubin, a red-orangish substance, is converted into urobilinogen, which is colorless. Urobilinogen then turns into urobilin, which is responsible for urine's yellow color.
What scientists didn't know was what enzyme was responsible for this process. Researchers from the University of Maryland and the National Institutes of Health identified BilR, or bilirubin reductase, as the enzyme that reduces bilirubin to urobilinogen.
In addition to finding the answer to a question that many have wondered about, these researchers discovered something that can lead to a better understanding of other medical phenomena.
“Now that we’ve identified this enzyme, we can start investigating how the bacteria in our gut impact circulating bilirubin levels and related health conditions like jaundice,” Xiaofang Jiang, one of the study's coauthors, told Maryland Today.
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For example, it could help scientists learn more about infant jaundice and inflammatory bowel disease. The researchers found "that bilirubin reduction is a core feature of a healthy adult human microbiome and that neonates are often missing bilirubin reductase during the period of the highest incidence of neonatal jaundice. Furthermore, we found that the prevalence of bilirubin reductase is decreased in patients with IBD," the study authors noted.
More research is needed to investigate the relationship between bilirubin reductase and jaundice, as well as bilirubin reductase and gallstones.
