How did Claude Bernard’s research change earlier ideas about the stomach’s role in digestion?

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

Through his study of the pancreas, Bernard discovered that pancreatic secretions are responsible for breaking down fat molecules into fatty acids and glycerin. This work was part of his broader contribution to experimental physiology, where he moved beyond the prevailing theories of his time to establish that biological processes are mechanistically determined by physico-chemical forces. By proving that digestion is not localized solely within the stomach, Bernard helped refine the medical understanding of how the body processes nutrients.123