Microbes to Fight Microbes

Abstract

For centuries, fermentation of milk products using specific bacteria or cultures has been a way to preserve dairy foods. In 1908, Metchnikoff suggested that ingested lactobacilli could displace toxin‐producing microorganisms in the gastrointestinal (GI) tract and thus promote health and prolong life (1). In the latter half of this century, evidence mounted in support of the concept that the preservation of gut microflora in animals is necessary to prevent infections. It was recognized that germ‐free animals are more susceptible to infection than animals colonized with microflora (2) and that giving fecal suspensions orally to animals could prevent infection (3). Fecal enemas were successfully administered to humans to control C. difficile infection (4); conversely, it was recognized that antibiotics can alter intestinal flora and induce diarrhea. All this information led to the concept that a healthy or balanced microflora is necessary for maintaining the health of the host; one way to maintain balanced microflora is to ingest exogenous bacteria in order to incorporate them into the gut milieu. Many published observations have claimed a variety of health benefits from several microbial agents. Among the benefits attributed to the consumption of these organisms are improvement of lactose absorption and tolerance, control of intestinal infections, anticarcinogenic properties, anticholesterolemic effects, and improvement of GI motility (5,6). These attributions became part of the nutritional folklore that has conferred upon yogurt and other cultured milk products the status of “health foods.‘’