Lactulose is produced by isomerization of lactose under alkaline conditions. It is a non-digestible sugar that passes through the small intestine intact and is fermented by beneficial bacteria (particularly Bifidobacterium and Lactobacillus) in the colon. This prebiotic action makes lactulose valuable in functional food applications. Medically, it is widely used as an osmotic laxative and for the treatment of hepatic encephalopathy. As a food ingredient, lactulose provides approximately 50–60% of the sweetness of sucrose and can be incorporated into dairy, beverages, and supplement products for its gut health benefits.