Lactase Persistence

Lactase persistence is the continued activity of the enzyme lactase in adulthood. Since lactase's only function is the digestion of lactose in milk, in most mammals species the activity of the enzyme is dramatically reduced after weaning. However in some human populations lactase persistence has recently evolved as an adaptation to the consumption of non-human milk and dairy products beyond infancy. The majority of people around the world remain lactase non-persistent, and consequently are affected by varying degrees of lactose intolerance as adults – though not all genetically lactase non-persistent individuals are noticeably lactose intolerant, and not all lactose intolerant individuals have the lactase non-persistence allele.