FACTORS AFFECTING THE ABILITY OF A HIGH BETA-GALACTOSIDASE YOGURT TO ENHANCE LACTOSE ABSORPTION

Lactose in yogurt is better absorbed by lactase-deficient subjects tha n is an equivalent quantity of lactose in milk, presumably because of the microbial activity of the beta-galactosidase present in yogurt. In this study, we describe a process that increases the beta-galactosida se of yogurt 5- to 6-fold and the ability of this high lactase yogurt to enhance lactose absorption in lactase-deficient subjects. These sub jects ingested the yogurt meals after a 12-h fast, and lactose malabso rption was determined by measuring breath hydrogen. Breath hydrogen wa s reduced 39% following ingestion of high lactase yogurt from that aft er consumption of conventional yogurt, indicating that the high lactas e yogurt enhanced lactose absorption. However, the reduction after hig h lactase yogurt was less than expected, given the 5- to 6-fold increm ent in beta-galactosidase measured in vitro. In vivo activity of beta- galactosidase requires that the enzyme resist acid denaturation in the stomach. The beta-galactosidase in high lactase yogurt was much less acid resistant than was the beta-galactosidase in conventional yogurt, and the relative inability of high lactase yogurt to enhance lactose absorption was likely due to the destruction of the beta-galactosidase in the stomach.