It is commonly known that raw milk will sour, but pasteurized milk will putrefy. The idea that putrefaction of the stools causes disease (i.e. intestinal autointoxication) originated with physicians in ancient Egypt (Chen and Chen 1989). The toxic process, however, was reversed by the consumption of lactic acid-producing bacteria that changed the colonic microflora and prevented proteolysis (Chen and Chen 1989).
Autointoxication is an ancient theory based on the belief that intestinal waste products can poison the body and are a major contributor to many, if not all, diseases (Ernst 1997). By ancient tradition, lactic acid bacteria (LAB) are involved in the production of fermented foods. German scientists found that foods rich in LAB constitute one quarter of the German diet and are characterized by a safe history, certain beneficial health effects, and an extended shelf life when compared with raw materials (Hammes and Tichaczek 1994).--I'm not sure where I got this information, possibly HSI or Body Ecology.