Lactose intolerance is a reduced ability to digest lactose, the main sugar found in milk. Most children and babies produce lactase enzyme, which splits the disaccharide lactose into its digestible component sugars (glucose and galactose), in their small intestine. However, in most of the global population, the production of lactase declines steeply in childhood, and around 70% of the world's adult population is lactose intolerant to some degree, due to reduced or no production of the lactase enzyme in adulthood.[1][2]
What is lactose intolerance?
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•Last Updated: May 16, 2025
Lactose intolerance is the reduced ability to digest lactose (the sugar in milk) due to a decline in lactase enzyme production after childhood. Approximately 70% of the global adult population experiences some degree of lactose intolerance.