Microbial-host interactions: selecting the right probiotics and prebiotics for infants.

Probiotics were originally used to influence human health through intestinal microbiota alterations. At present, probiotics and their effects on human health have been demonstrated both within different food matrices and as single or mixed culture preparations. The health-promoting properties are known to be strain-dependent. Thus, strain identification and characterization are important: only well-characterized strains identified with modern techniques are acceptable, especially if health claims are desired. Linking the strain to a specific health effect as well as to enable accurate surveillance and epidemiological studies are important targets. Currently there are specific strains which have demonstrated beneficial in vitro properties and clinically proven health benefits. Such specific probiotics have been included in recommendations on pediatric nutrition. The model is the microbiota of the healthy breastfed infant. Molecular methods in microbiota assessment enable more specific probiotics and prebiotics to be identified for infants with aberrancies in intestinal microbiota. Probiotic products require information on the concentration and viability of the strain(s) in the product as well as data on required dosages. Continuous control of probiotic strains or strain combinations is a must as small changes in production process or growth media may significantly affect the properties of a strain or strain combination.