What Is Lactase Nonpersistence?

The inability to digest lactose, due to lactase nonpersistence, is a common trait in adult mammals, except in certain human populations that exhibit lactase persistence. It is not known how the lactase gene is dramatically downregulated with age in most individuals but remains active in some individuals.

What is the mechanism of lactase persistence?

Lactase persistence is the continued activity of the lactase enzyme in adulthood. Since lactase's only function is the digestion of lactose in milk, in most mammal species, the activity of the enzyme is dramatically reduced after weaning.

What causes specific lactase persistence?

The lactase persistence trait is more common in populations that practice cattle herding and dairy farming, and it is related to genetic selection of individuals with the ability to digest lactose.