"Soil health is essential for human health, and its scent is the promise of a rich and healthy life for us and future generations."
Not long ago, we had the fortune of exploring the highlands of Támesis, seeking to understand the biology of its soils. We traveled as part of a scientific cooperation project between Universidad EAFIT, SaBio, Cartama, El Globo Reserva Natural,and Comfama through the Agroparque Biosuroeste.
Our project aims to explore soil trophic networks—the intricate web of interactions between microorganisms (bacteria, fungi, microinvertebrates, and many others) that, when in a healthy state, enable the flow of nutrients and energy, allowing plants to reach their full potential.
To map the health status of the soils we studied, our first step with each sample was to engage all our senses, including smell and even taste. (Hans Jennyone of the founding fathers of soil science, advocated for the daily consumption of soil for human health—and he lived to be 92 years old.
It didn’t take long for us to notice something fascinating: when smelling and tasting soils from mature, diverse, and ecologically complex ecosystems—in other words, healthy soils—we felt a certain... euphoria.
In this blog, we share what we realized upon returning to the city. The scent of soil can have a powerful effect on our emotions and mood. Studies have shown that the earthy aromas of soil can reduce anxiety and stress while enhancing overall emotional well-being.
A reinforcement of our conviction that healthy soil is one of the foundational links in the onehealth, the starting point for promoting human, animal, and environmental health.
Content Summary:
The Connection Between Soil Health and Human Health
The evidence on the impact of soil health on human health is growing every day.
Last year, David Montgomery and collaborators published a preliminary comparison of the nutritional profiles of foods grown in regenerative soils versus the same products obtained from conventional systems. Growing in regenerating soils consistently resulted in foods with higher micronutrient and beneficial phytochemical content—in other words, more nutritious foods.
Healthy Soil and Emotions
Healthy soils can also have a positive effect on our emotional well-being.
The earthy fragrance of healthy soils, with its mold-like undertones, is primarily composed of geosmin and methyl isoborneol. In 2017, Korean researchers demonstrated that both compounds, when inhaled, could alter brain activity and induce states of calm.
That same research group, seeking to understand the therapeutic mechanisms of soil, found last year that handling soils containing the bacterium Streptomyces rimosus—a natural producer of both compounds—could increase blood serotonin levels and enhance alpha brain waves, which are associated with relaxation and mental clarity.
Streptomyces rimosus was already well-known in the medical field, as this naturally occurring soil bacterium was one of the sources for the discovery of tetracycline antibiotics in the 1940s—an essential medical breakthrough. The neuromodulatory role of the volatile compounds it produces in soils expands its contributions to human well-being.
Other soil microorganisms have also been linked to serotonin production, a neurotransmitter associated with mood regulation and learning, among many other functions.
Mycobacterium vaccae, when added to soils handled by human volunteers, had a similar effect to Streptomyces rimosus, reducing stress and increasing alpha brain waves. But Mycobacterium vaccae had already proven its potential for nervous system modulation. Vaccines derived from this bacterium have been shown to control inflammation in mice and rats, and through immune system regulation, they induce serotonin production in these animals.
The neuromodulatory effect of the volatile compounds produced by Mycobacterium vaccae (distinct from geosmin) suggests that injections are unnecessary, as their benefits can be experienced simply through inhalation.
The "Old Friends" Hypothesis
The connection between inflammation and emotional states, revealed by Mycobacterium vaccae, leads us to link soil health with human microbiota health.
The "hygiene hypothesis," reformulated as the "old friends hypothesis," suggests that reduced exposure to environmental microorganisms during childhood leads to ecological imbalances (dysbiosis) in our gut microbiota—a complex microbial community fundamental to human biology.
This imbalance causes improper immune system development, increasing the likelihood of chronic inflammation-related conditions such as irritable bowel syndrome, Crohn’s disease, and asthma.
How Our Treatment of Soils May Be Impacting Our Mental Health
One of the most surprising discoveries in human microbiota research is the close relationship between the gastrointestinal and nervous systems, known as the gut-brain axis.
Growing evidence is linking gut microbiota imbalances with neuroinflammatory conditions such as multiple sclerosis, Parkinson’s disease, and even Alzheimer’s.
Although some herbicides are considered relatively harmless to humans because they target metabolic pathways absent in our genes, this perspective changes when we consider humans as holobionts—intimately associated with the microorganisms that inhabit us and evolve alongside us.
Glyphosate, for example, targets a crucial metabolic pathway in plants, but one that is also used by many microorganisms. Among the most sensitive members of our microbiota to glyphosate exposure are the Lactobacillus and Bacteroides genera. Both groups play a direct role in producing compounds that modulate inflammation and anxiety.
Recently, a group of Canadian researchers observed a correlation at the North American level between rising anxiety rates in young people and increasing glyphosate use. By understanding glyphosate’s mechanistic impact on gut microbiota, and the microbiota’s influence on neuroimmune development, they hypothesized that the connection might be more than just correlational., una asociación íntima entre nosotros y los múltiples microorganismos que en nosotros habitan y que con nosotros evolucionan.
With our project, we aim to define what constitutes a healthy soil in the Colombian context, identifying regeneration pathways for degraded soils. Although we are just beginning to explore the characteristics that define soil health, experiencing its effects on our own well-being has deepened our understanding of the intrinsic connection between soil health and human health.
Join us in soil regeneration. Together, we can create a better future for our communities and the planet!
''Essentially, all life depends on the soil.''
* Nicolás Pinel is an Associate Professor in the Natural Systems and Sustainability Area at the School of Applied Sciences at EAFIT University. The cited project is funded by Universidad EAFIT through the first Biosuroeste project call under the special framework cooperation agreement between the Biosuroeste Corporation and EAFIT University.
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