 In most mammals, intestinal absorption of nutrients is thought to be dominated by transcellular transport, e.g., glucose is primarily absorbed via the SGLT1 transporter and other glucose transporters.Paracellular absorption therefore plays only a minor role in glucose absorption, although there is evidence that paracellular pathways become more available when nutrients are present in the intestinal lumen.In contrast, small flying vertebrates (small birds and bats) rely on the paracellular pathway for the majority of glucose absorption in the intestine.