Physiology and pathophysiology of intestinal absorption

Area of Science:

• Gastroenterology
• Human Physiology
• Nutritional Science

Background:

• Carbohydrate (CHO) digestion and absorption rely on pancreatic alpha-amylase and Na(+)-dependent transport.
• Protein digestion involves intact peptide absorption or membrane hydrolysis followed by amino acid absorption.
• Lipid absorption is a complex process including emulsification, lipolysis, micellar formation, and chylomicron transport.

Purpose of the Study:

• To elucidate the intricate mechanisms of nutrient digestion and absorption in the human body.
• To identify rate-limiting steps and factors influencing the absorption of carbohydrates, proteins, and lipids.

Main Methods:

• Review of established physiological processes for nutrient digestion and absorption.
• Analysis of enzymatic hydrolysis, transport systems, and cellular mechanisms involved.
• Identification of factors affecting the rate of nutrient uptake.

Main Results:

• Na(+)-dependent transport is a critical determinant of carbohydrate absorption rate.
• Dietary fibers, alpha-amylase inhibitors, and alpha-glucosidase inhibitors can delay carbohydrate absorption.
• Lipolysis and micellar formation are the most critical steps in lipid digestion.

Conclusions:

• Nutrient absorption is a multi-step process influenced by meal composition, digestion efficiency, and intestinal motility.
• Understanding these mechanisms is crucial for managing nutrient uptake and related physiological processes.
• Targeting specific steps, like lipolysis and micellar formation, could modulate lipid absorption.