Why did Claude Bernard’s findings challenge earlier ideas about the stomach’s role in digestion?

Claude Bernard’s research fundamentally shifted the scientific understanding of digestion by demonstrating that the primary digestive processes occur in the small intestine rather than the stomach, as had been previously believed.1

Through his study of the pancreas, Bernard discovered that pancreatic secretions play a critical role in breaking down fat molecules into fatty acids and glycerin. By proving that these essential chemical transformations take place after food leaves the stomach, he challenged the prevailing view that the stomach was the central site of digestion. This work was part of his broader contribution to establishing experimental medicine, as he emphasized the necessity of using guiding hypotheses to investigate physiological functions.123