alactasia

absence or deficiency of the enzyme lactase, which is essential for the digestion of milk sugar (lactose). All babies have lactase in their intestines, but the enzyme disappears during childhood in about 10% of northern Europeans, 40% of Greeks and Italians, and 80% of Africans and Asians. Alactasia causes symptoms only if the diet regularly includes raw milk, when the undigested lactose causes diarrhoea and abdominal pain.