ABSTRACT
Milk contains a unique sugar, lactose, which turns out to be more interesting than it might fi rst appear. The ability to digest this sugar varies across the lifecycle and among populations, and it turns out that drinking milk presents a challenge to many of the world’s populations. In this chapter I describe the biology of lactose digestion and population variation in this trait, and then turn to how this diversity intersects with dietary policies in the U.S. that encourage milk consumption. The linguistic terms employed in discussions of this variation vis-à-vis milk promotion provide insight into how different institutions involved in designing or implementing dietary recommendations view this important aspect of human biological diversity.
