Digestion, absorption, and fermentation of carbohydrates in the newborn

In the newborn, sugars present in human milk and formulas are assimilated by both small intestinal digestion and, especially in the case of lactose, by colonic bacterial fermentation. Colonic fermentation of carbohydrate serves three major functions: conservation of a fraction of the metabolizable energy of dietary carbohydrate that is not absorbed in the small intestine, prevention of osmotic diarrhea, and production of short chain fatty acids that stimulate sodium and water absorption, serve as fuel for coloncytes, and stimulate cell replication in colon and small intestine.