6533b861fe1ef96bd12c4267

RESEARCH PRODUCT

Adult Lactose Tolerance Is Not an Advantageous Evolutionary Trait

subject

description

To the Editor. I read with great interest the recent article from Fomon1 in which he refers to the well-known hypothesis that views the variable frequencies of lactase persistence in different human populations and, consequently, the possibility for some adults to feed on milk (lactose tolerance) as an advantageous evolutionary trait that has been genetically determined and brought about through centuries of natural selection. This notion stands as a common statement in current medical literature, and most authors have accepted its validity since the 1970s.2,3 Because adult mammals are lactose-intolerant, this hypothesis is, moreover, based on the low percentage of lactose malabsorption and high enterocyte lactase activity (0–30%) among populations originating in northwestern …