ADULT HYPOLACTASIA, MILK CONSUMPTION, AND AGE-SPECIFIC FERTILITY

Beta-galactosidase (lactase) allows the digestion of lactose as its co mponent sugars, galactose and glucose. Considerable variation exists w orldwide in the prevalence of adults who lose the ability to digest la ctose after infancy (hypolactasia) as well as in the amount of milk pr oducts they consume. Clearly, those populations in which hypolactasia is infrequent and milk consumption high will have greater dietary expo sure to galactose. Because there is clinical and experimental evidence that galactose may be toxic to ovarian germ cells, the authors sought to determine whether age-specific fertility rates in various countrie s correlate with the prevalence of adult hypolactasia and per capita m ilk consumption by analysis of published data on these variables. The authors found significant correlations among these variables such that fertility at older ages is lower and the decline in fertility with ag ing is steeper in populations with high per capita consumption of milk and greater ability to digest its lactose component. These demographi c data add to existing evidence that dietary galactose may deleterious ly affect ovarian function.