
The gastrointestinal tract is teeming with live microorganisms, both of friendly and pathogenic nature. The sum of these bacteria, our microflora, can be adversely affected by stress, medication, diet, aging, and other factors. Probiotics are beneficial strains of bacteria that confer benefits to the host including stimulation of the immune system, prevention of the growth of "bad" microorganisms, and the production of nutrients.
The most well known and well represented group of probiotics in the intestinal microflora are species from within the Lactobacillus and Bifidobacteria genera. In the womb babies are intestinally sterile (no intestinal bacteria are present). Once the child passes through the vaginal tract (or via C-section delivery), the infant immediately begins to colonize bacteria throughout the digestive tract. At this very young age, the majority of species come from the Bifidobacteria genus, with smaller amounts of Lactobacillus also present. As the infant ages, his or her microflora begins to shift to a higher percentage of Lactobacillus species, and eventually by the age of three or four years old, the child's microflora profile resembles that of an adult.

