Bifidobacterium for Infants: Essence and Efficacy

Abstract

Bifidobacteria are the predominant bacteria in the gastrointestinal tract of an infant. The colonization pattern of the bifidobacteria is affected by mode of delivery and types of feeding. Newborns from vaginal delivery are firstly exposed to maternal vaginal, fecal, and skin bacteria, such as Lactobacillus, Prevotella, and Atopobium. In the few days after birth, a reduced environment in the gastrointestinal tract favors the arrival and proliferation of obligate anaerobic bacteria, such as Bifidobacterium, and subsequently becomes predominant in the infant's gastrointestinal tract. Also, in breast-fed infants, Bifidobacterium concentration is higher than formula-fed infants as human breast milk contains human milk oligosaccharides (HMOs) which are bifidobacterial growth-promoting factors. In addition to HMOs, existing lysozyme in breast milk could be involved in selection of infant-type Bifidobacterium as inhabitants of the infant intestines. Bifidobacteria colonization in infants initiates the development and maturation of the infant's naive immune system by stimulating dendritic cells through Toll-like receptors (TLR) and leads to differentiation of naive T lymphocytes into Th1 cells by recognizing the peptidoglycans in bifidobacteria. Hence, immune response, control intestinal inflammation, and mucosal tolerance are initiated. Production of immunoglobulin A (IgA) is also stimulated by the presence of bifidobacteria to stimulate intestinal antigenic ability. Bifidobacteria are able to prevent and treat atopic diseases in infants by restoring Th1/Th2 balance and enhance the production of IFN-gamma. In addition, bifidobacteria are also effective in reducing the duration of gastrointestinal diseases by modification and stabilization of GIT microflora, reduction in the duration of retrovirus shedding, reduction of GIT permeability, as well as induction of general immune response by increasing IgA antibodies. In respiratory tract infections, bifidobacteria enhance several immune responses by increasing immune cell activity, modulating signals in epithelial and immune cells, increasing local and systemic antibody production, and inducing phenotypic changes in dendritic cells. Considering that Bifidobacterium are the natural inhabitants of infant intestines, and much clinical evidence of efficacy to infants have been documented, Bifidobacterium strains are highly encouraged for use as probiotics for infants.