Bilirubin: Both villain and hero?

Bilirubin, the bile pigment that yellows the skin of babies born with jaundice, is generally considered a toxic molecule. According to a new study, however, bilirubin may actually protect cells from dangerous oxygen-containing molecules called free radicals.

Bilirubin forms during the breakdown of hemoglobin, the oxygen-carrying protein in blood cells, and can build up to high concentrations in the blood.