What Do Probiotics Do?
Probiotic bacteria work by attaching and adhering to the soft lining of your intestinal tract. After adherence, they begin to eat the same food you eat, converting it into lactic acid. Lactic acid is the primary mechanism probiotic bacteria use to promote a healthy digestive system.
As they grow and reproduce, probiotics keep your digestive tract healthy by promoting the growth of all beneficial bacteria which colonize the intestinal walls which further stimulates the growth of other beneficial microogranisms.
Lactobacillus ("lacto") strains are most active in the small intestine while Bifidobacterium ("bifido") strains work best in the large intestine.