Mycobacterium vaccae: The feel-good bacteria in soil

When most people picture mental health treatments, they tend to imagine therapy rooms, medication plans, or mindfulness exercises. Yet one of the most powerful tools for improving emotional well-being can be found not in a clinic but in the soil beneath our feet. A growing body of research shows that gardening is far more than a relaxing hobby. It is an evidence-supported pathway to improving mood, reducing stress, strengthening emotional regulation, and even preventing the onset of certain mental health disorders.

The Microbial Connection: How Soil Supports Brain Chemistry

One of the most remarkable findings in this field involves Mycobacterium vaccae (M. vaccae), a harmless, naturally occurring soil bacterium. When humans come in contact with soil when planting, weeding, or simply breathing outdoor air, this bacterium can enter the body and influence the brain’s chemistry.

Recent research has shown that exposure to M. vaccae stimulates the brain to produce increased levels of serotonin, a neurotransmitter essential for mood regulation, cognitive clarity, and emotional stability. Even more striking is the fact that this serotonin-boosting effect behaves similarly to the mechanism of selective serotonin reuptake inhibitors (SSRIs), a widely prescribed class of antidepressants (Holbrook et al., 2023). This means that something as simple as tending a garden allows the body to naturally activate biochemical pathways associated with improved mood, reduced anxiety, and enhanced resilience.

Emotional Benefits of Gardening

Beyond the soil-microbe interaction, gardening as an activity has been strongly linked to improved emotional well-being. Engaging with plants, fresh air, and natural landscapes consistently reduces feelings of stress, anger, fear, and sadness (Thompson, 2018). The rhythmic actions involved in gardening, like digging, pruning, watering, and sowing, all help regulate the nervous system and support a sense of grounding.

These emotional benefits likely stem from multiple overlapping mechanisms, including sensory stimulation, gentle physical movement, exposure to natural light, and the restorative qualities of green space. Together, these factors create calming physiological responses that can help counteract symptoms of depression and anxiety.

A Natural Pathway Toward Wellness

Increasingly, researchers view gardening not only as a therapeutic hobby but also as a preventive mental health strategy. Engaging with plants builds daily routines that support emotional regulation, increase time spent outdoors, and strengthen feelings of purpose and accomplishment. These habits form protective buffers against chronic stress, which is known to exacerbate or trigger mental health disorders.

The research is clear: gardening supports mental health through multiple interconnected pathways, from the microbiology of M. vaccae to the emotional regulation fostered by spending time outdoors. When we touch soil, plant seeds, or tend a vegetable bed, we are not simply cultivating plants—we are cultivating resilience.

For communities seeking accessible, low-cost approaches to psychological well-being, gardening stands out as a powerful and evidence-based option. Whether in a backyard, on a balcony, or in a home-installed vegetable garden, the therapeutic effects of working with soil offer a profound reminder: the natural world is one of our oldest and most effective healers.

References

Holbrook, B., Yang, J., & Hwang, S. (2023). Microbial influences on neurochemical pathways: The antidepressant-like effects of Mycobacterium vaccae. Journal of Environmental Psychology, 88, 102036.

Thompson, R. (2018). Gardening for health: A regular dose of gardening. The Lancet Psychiatry, 5(11), 899–900.