Gnotobiotic Animals in Nutrition Research

At the beginning of this century, Metchnikoff (1907) speculated that certain microorganisms of the intestinal tract and their ‘putrefactive’ activities were potentially deleterious. He believed that their harmful effects could be interrupted or suppressed by the consumption of foods such as yoghurt. His observations of the longevity of peasants in Eastern Europe who regularly consumed large amounts of yoghurt, added weight to this.