The enzyme that turns urine yellow has finally been identified. A compound called urobilin has been known for more than 125 years to be responsible for the yellow color of urine.
But exactly how it is created from red-orange bilirubin has not been clear. This waste product from broken-down red blood cells can lead to jaundice and neurological damage if too much builds up in the body. The enzyme bilirubin reductase is produced by intestinal microbes and converts bilirubin into colorless urobilinogen, which breaks down to yellow urobilin./BGNES
