sucrose

Sucrose is a non-reducing disaccharide found commonly in table sugar, consisting of glucose and fructose joined by an α-1,2-glycosidic linkage between their anomeric carbons—this bond configuration makes sucrose a non-reducing sugar (no free anomeric carbon available for oxidation, unlike lactose or maltose). Digestion occurs at the intestinal brush border via the enzyme sucrase-isomaltase, which cleaves sucrose into glucose and fructose for absorption via SGLT1 (glucose, sodium-dependent) and GLUT5 (fructose, facilitated diffusion), respectively, followed by GLUT2 transport into the bloodstream. Congenital sucrase-isomaltase deficiency is an autosomal recessive disorder presenting in infancy with osmotic diarrhea, bloating, and failure to thrive upon introduction of sucrose-containing foods (fruits, table sugar) into the diet; breast milk (lactose-based) is typically tolerated. Diagnosis involves a positive hydrogen breath test after sucrose ingestion and a negative stool reducing substances test (since sucrose is a non-reducing sugar) unless hydrolyzed. Management involves dietary sucrose restriction and enzyme replacement (sacrosidase). Sucrose is also clinically relevant as a component of oral rehydration solutions and as a substrate that promotes dental caries via Streptococcus mutans, which uses sucrose to form glucan-based biofilms/plaque.