Fermented milk has long been recognized as a health-promoting food in many cultures; however, its beneficial effects were first scientifically articulated by Élie Metchnikoff in the early twentieth century. Metchnikoff proposed that intestinal putrefaction and harmful fermentation, driven by specific microbial activities, contribute to chronic physiological burden. In contrast, fermentation mediated by lactic acid bacteria can suppress these processes through biological acidification of the intestinal environment. In his classical work, Metchnikoff emphasized fermented milk as a dietary means of modulating the intestinal microbiota and highlighted the role of the Bulgarian bacillus (Lactobacillus delbrueckii subsp. bulgaricus) in lactic acid production. He further argued that the administration of living lactic acid bacteria is more effective than the direct intake of lactic acid, thereby anticipating the modern concept of probiotics. This study presents a complete Korean translation of Metchnikoff’s original text on fermented milk, with historical terminology systematically aligned with contemporary scientific nomenclature. By revisiting this classical work, the study aims to clarify the historical foundations of fermented milk research and demonstrate its conceptual continuity with modern studies on probiotics and the gut microbiota.
Sejong Oh (Sun,) studied this question.