How did Claude Bernard’s work on glycogen change the understanding of digestion?

Claude Bernard’s discovery of the glycogenic function of the liver fundamentally shifted the scientific understanding of digestion. Prior to his work, it was believed that the digestive system functioned solely to break down complex molecules into simpler ones.

Bernard’s research revealed that the body also performs the reverse process: it builds up complex molecules from simpler ones. Specifically, he discovered that the liver produces glycogen, a starchy substance that serves as a carbohydrate storage reserve. This reserve can be broken down into sugars as needed, allowing the body to maintain a constant level of sugar in the blood.

This discovery was a critical step in establishing the concept of homeostasis, demonstrating that the body actively regulates its internal environment to remain stable despite changing external conditions.12