Final answer:
Physiologic jaundice is common in newborns due to the immature liver's inability to effectively process and clear bilirubin from the blood, coupled with an underdeveloped blood-brain barrier. Breast milk aids in reducing bilirubin levels while phototherapy is used for higher levels to prevent brain damage.
Step-by-step explanation:
Newborns often experience physiologic jaundice due to their developing bodies. When newborns are born, bilirubin, a yellowish substance produced by the breakdown of red blood cells, must be processed by the liver and excreted in the stool. The immature liver of a newborn may not process bilirubin as efficiently, resulting in higher levels in the blood. This condition, known as hyperbilirubinemia, causes the yellowish color of jaundice. To help control bilirubin levels, breast milk plays a crucial role due to its laxative properties, aiding in the excretion of both bilirubin and meconium. However, if levels of bilirubin become too high, they can be toxic, particularly to the brain, since infants do not have a fully developed blood-brain barrier. Phototherapy, using UV light, is used to treat high levels of bilirubin and prevent potential brain damage.