Inactivation of Digestive Proteases by Deconjugated Bilirubin and the Physiological Significance of Fasting Hyperbilirubinemia

It has been observed more than a century ago that in humans as well as in many animals, there was a significantly increase in blood bilirubin level during fasting. However, the physiological significance for this increase remains largely unknown. As it is found that digestive proteases are inactivated by free (or deconjugated) bilirubin, here I suggested that fasting hyperbilirubinemia would be a mechanism to save bilirubin during fasting to meet the anticipated increased needs to protect the gut against the damage by the increased luminal pancreatic proteases during and after feeding.