 Prebiotics are highly effective and important for many applications in medicine. They are not absorbed and do not contribute to human nourishment, but rather exert a profound effect on the human bowel flora. The principal effect on the human bowel flora is to stimulate the growth of Bifidobacterium and Lactobacillus species. These are benign organisms in that they are seldom involved in infections or other pathological processes. However, numerous health promoting benefits of these bacterial genera have been noted, with effects on infectious and non-infectious disease. They induce host genes involved in innate immunity, sometimes in collaboration with other elements of the gut flora such as Bacteroides thetaiotaomicron and Lactobacillus casei. Animal studies 2 indicate a protective effect against bacterial translocation from the GI tract. An extensive cataloguing of genomes of bifidobacteria and other intestinal bacteria reveals that the bifids play a very significant role in many important areas such as carbohydrate, amino acid, nucleotide, lipid, inorganic ion transport and metabolism; energy production and conversion; cell wall and membrane biogenesis; signal transduction mechanisms; transcription and translation; and defense mechanisms . 