More than 125 years ago, scientists identified urobilin as the yellow pigment in urine, but they didn't know what was ...

Most people have never wondered how and why their urine became yellow. But scientists have been puzzling over it for more than a century. Back in the late 19th century, medical researchers ...

It's all to do with our gut, and how we break down cells. We already knew that the yellow comes from a substance called urobilin, but now scientists know why that substance is made in the first place.