Elie Metchnikoff (1845–1916)

The use of human-commensal bacteria as therapeutic agents dates back over a thousand years, long before the modern discovery of bacteria. In the early 20th century, immunologist Ilya Metchnikoff proposed that colonic flora could influence mental capacity, laying the groundwork for the gut-brain axis hypothesis (1) and conceptualized the role of the gut on host physiology and pathology (2).

In his 1907 article, “Essais optimistes,” Metchnikoff proposed a causative link between microbes and aging mechanisms and suggested a central role in senescence progression for compounds resulting from microbial intestinal putrefaction (3).

A century ago, Elie Metchnikoff (a Russian scientist,…