In 1904, Professor Eli Metchnikoff, gave a public lecture presenting his hypothesis that the exceptional health and longevity of Bulgarian peasants was, in part, due to microbes in the fermented milk products that they consumed in large amounts (1). With this lecture he introduced the idea of probiotics, microbes that promote health. His lecture made front page news and set off a global craze for yogurt and other fermented dairy products as health foods. Four years later he would go on to win the Nobel Prize in 1908 for his work on immunity but over a century would pass before we had the technology necessary to validate his hypothesis.
Fast forward to 2021, a lab at Stanford reported the results of a clinical trial in which they compared the impact on immune function, systemic inflammation, and gut microbiome diversity of two diets. In one, the subjects ate six servings of fermented food daily and in the other, they doubled their intake of fiber. After 10 weeks they found (2):
These findings suggest that we have only just begun to understand the relationship between our health and microbiome. While more research needs to be done, the Hippocrates quote “Let thy food be thy medicine, and let thy medicine be thy food” stands true.