Pediatric Applications of Probiotics

Abstract

The concept of probiotics was established early in the last century at the Pasteur Institute by the work of Metchnikoff, who hypothesized that the ingestion of fermented milk products had a beneficial impact on the health and lifespan of Bulgarian peasants [1]. The formal term probiotic first was referenced in 1954 by Ferdinand Vergin in an article discussing the effects of antibiotics on beneficial intestinal bacteria [2]. Fuller often is credited with establishing the first definition of probiotics as a bacterial product inferring benefits based on his work with animals [3]. The accepted definition of a probiotic encompasses the cumulative state of the research in this area. A probiotic is a beneficial species of bacteria that colonizes and replicates in the human intestinal tract and provides a positive benefit to the host. Pediatric applications of probiotics are widespread, with the primary applications being diarrhea and allergic disorders. This article reviews normal infant colonization, how native intestinal bacteria influence health, and research regarding probiotic use in infants and children. COLONIZATION At birth, the intestine is sterile. The digestive tract provides an excellent environment for bacterial growth, with minimal oxygen and plentiful nutrients. This nutrient-rich aqueous environment is an ideal culture medium for bacteria. Additionally, the gut epithelium itself is lined with mucins, extensively glycosylated proteinaceous compounds that function as binding sites for many of the gut bacteria and function to assist or inhibit bacterial attachment to the underlying epithelium or antigen sampling cells. Some probiotics are capable of upregulating mucin genes in the gut and thereby altering bacterial flora [4]. The establishment of native bacteria that are able to thrive in the infant’s developing intestinal tract without provoking an adverse immunological response is a complex process that is completed in the first year and remains relatively stable throughout life [5]. The establishment of native flora creates