IMPROVEMENT OF LACTOSE DIGESTION BY HUMANS FOLLOWING INGESTION OF UNFERMENTED ACIDOPHILUS MILK - INFLUENCE OF BILE SENSITIVITY, LACTOSE TRANSPORT, AND ACID TOLERANCE OF LACTOBACILLUS-ACIDOPHILUS

The influence of bile sensitivity, lactose transport, and acid toleran ce of Lactobacillus acidophilus on in vivo digestion of lactose was in vestigated. Four strains of L. acidophilus exhibiting varied degrees o f lactose transport, beta-galactosidase activity, and bile sensitivity were used to prepare unfermented acidophilus milks. Lactose malabsorp tion was evaluated by measuring breath H-2 excretion of 11 lactose mal digesting subjects following ingestion of four acidophilus test milks. Test meals were fed in a randomized double-blind protocol. Consumptio n of acidophilus milk (2% fat) containing strains B, N1, and E signifi cantly reduced mean total H-2 production compared with that of the con trol reduced-fat (2% fat) milk, but milk containing strain ATCC 4356 d id not differ from the control. Acidophilus milk containing L. acidoph ilus N1 was the most effective of the four acidophilus milks in improv ing lactose digestion and tolerance. Strain N1 exhibited the lowest be ta-galactosidase activity and lactose transport but the greatest bile and acid tolerance of the four strains. The results indicated that bil e and acid tolerance may be important factors to consider when L. acid ophilus strains are selected for improving lactose digestion and toler ance.