Does Soil Contribute to the Human Gut Microbiome?

YES - both directly and indirectly. A very interesting paper was recently published which delved into the microbial world of soil and how this contributes to, and is very similar to, our very own gut ecosystems.Here are some important takeaways:

• Soil and the human gut contain approximately the same number of active microorganisms, however, human gut microbiome diversity is only 10% that of soil Both have seen dramatic losses in biodiversity over the last century.
• Worldwide urbanization, as well as the mechanization of agriculture, has dramatically increased during the last century. In combination with the use of agrochemicals such as mineral fertilizers and pesticides, soil biodiversity is reduced. In human medication too, a strong transformation occurred during this time by the use of antibiotics and hormones.
• Both the human intestinal microbiome as well as the soil/root microbiome as 'superorganisms' which, by close contact, replenish each other with inoculants, genes and growth-sustaining molecules.
• Both are considered “functional ecosystems” that are open systems with large surface areas over-populated by microbes.
• A recent study of the gut microbiome of terrestrially living baboons showed that soil is the most dominant predictor for shaping the gut microbiota with a 15 times stronger effect than host genetics.
• Rural environments that are rich in microbiota, such as traditional farms, have been shown to have health benefits in humans. In particular, manual agriculture with close contact to soil, practiced by Amish communities, in a microbial rich rural environment has shown significant beneficial effects on immune functions compared to rural Hutterites who practice mechanised agriculture.
• Both the soil biome and the human biome follow circadian cycles/ rhythms.
• Similar to the human gut, the rhizosphere offers a vast surface (via root hairs, or microvilli), and is heavily involved in nutrient acquisition and uptake.
• Both provide protection against pathogens and modulate host immunity – in a myriad of ways.

And, last but not least, a loss of biodiversity significantly threatens ecosystem functioning in both soil and the human gut microbiome, hence the urgency to turn all our focus and energy towards solutions, starting with what’s under our feet.