We're told to watch out for color changes in our pee, as the loss of its normal, yellowish hue could be a sign of a medical problem — but what actually makes urine yellow in the first place?
Turns out, scientists didn't know the exact answer to this question until recently. Now, researchers have discovered that pee's golden color is caused by an enzyme called bilirubin reductase, which is produced by bacteria in the gut. The scientists reported their findings in a new study, published Wednesday (Jan. 3) in the journal Nature Microbiology.
