Regional organization of nutrient absorption across the small intestine.

Molecular, cellular, and functional organization of nutrient absorption varies regionally along the small intestine, with a comprehensive framework now emerging to define this zonation.

• Why it matters: Understanding the regional differences in the small intestine is crucial because they underpin nutrient absorption and protection against environmental insults, yet a detailed molecular basis has been lacking.
• What they did: The review highlights epigenetic and transcriptional features of small-intestinal zonation across axes, examines mechanisms establishing regional gene expression during development, and integrates molecular data with physiological insights.
• The result: This refined model of the intestinal functional landscape emphasizes the importance of regional tissue environments, which may inform targeted approaches to gastrointestinal diseases affecting specific regions.