Urban Agriculture & Mental Health: A Survey Detecting Quantifiable Biomarkers
This past Summer, I had the opportunity to take an urban agriculture course as part of my master’s candidacy coursework at NYU Steinhardt. My dog Jackie O had passed away a few days prior and I was obviously distraught. I knew this course would be a great distraction and that it would be pleasant to be out in the open sunshine at the NYU Urban Farm in SoHo twice a week. I didn’t realize how healing it would actually be to interact with living plants, visiting birds and the ocassional butterfly. I was intrigued and wanted to learn what was making me feel so much better. I decided to write my final research paper and here’s what I found out.
Urban Agriculture and Mental Health: A Survey in Detecting Quantifiable Biomarkers
Introduction
Many will agree that there is a vast array of potential health benefits to be gained when engaging in urban farming, including the pride that comes with nurturing a growing, living being, the access to local produce, camaraderie to be found in community and a connection to nature and a local food system. In addition to farming, humans have revered cultural practices such as zen gardens and the art of forest bathing for centuries. These sacred practices have existed around the world as outlets for recreation, artistic expression and annexes of wellness.
The following research is a survey on using quantifiable biomarkers to establish a possible correlation between urban farming and an effect on an individual’s mental health. Are there actual chemical reactions that can be recorded in the body such as a change in microbiome colonization or brain neurotransmitter chemistry in the gardening community? Are there noted health benefits in absorbing negative electrons in the practice of grounding? Can these quantitative markers convince practitioners and the public to include gardening in their wellness regimes?
The purpose of this research lies in the fact that many humans gravitate towards statistics when making decisions. Numbers and values in viable biomarkers can be powerful measures in convincing folks to frequent an urban garden or an equivalent green oasis in an effort to elevate their mental health. This would be a major win for both the humans and plants.
Evolutionary Roots
The human race made the transition from a nomadic hunter-and-gatherer lifestyle to one filled with agricultural fields approximately ten thousand years ago. The transition was thought to be met with a dynamic shift in microbial gut composition as humans now had more direct, repeated exposure to cultivated soil (Brown 2). Homo sapiens continued to build an evolutionary advantage by becoming omnivores. This caused them to colonize a diverse and fluid microbiota that adapts to changing environments, diet and life stages.
Studies show that humans simply have an innate preference for green spaces and natural landscapes because this is where we spent 99.5% of our evolutionary history. One theory calls it “inborn biophilia” which suggests that “nature is full of signs that can guide our adaptive responses towards well-being (Mencagli 49)”. More specifically, green spaces hold a “regenerative powder of psychophysical recuperation that comes from empathetic engagement with green space (Mencagli 51)”.
“Green plants have been on the earth longer than we have. By the time humans appear, plants have been flourishing for more than a hundred million years. They produce the oxygen we breathe and they are a precondition for life on the earth as we know it. It’s about time we got back in touch with them again (Viumdel 164).”
Humans were wanderers that were rewarded once they encountered lush plant life. Plants signaled a water source, food, and shelter from the elements (Viumdel 57). We have evolved to avoid barren lands. Seeking more plants is at the very core of our survival.
Zen Gardens: A Cultural Phenom
Zen gardens were first exalted by Buddhist monks in Japan as a means of restoration, meditation and an antidote to the stressors of daily life. The idea was to impart a sense of tranquility to the human spirit by employing elements of nature which was meant to restore internal balance.
“The sensory image a Zen garden makes is one of its most enduring qualities. Dappled light soothes the spirit and lowers stress levels. Sound is also a powerful element. The swishing of bamboo on a hot day speaks of the ocean and transports the garden visitor into another realm. The gentle gurgle of a stream over pebbles lightens the heart and encourages the child to resurface within the adult. Sparkling waterfalls add a refreshing sound that calls to mind tranquil mountains in distant lands. With these sights the visitor is able to go on a mental journey to a place that is unconnected with turmoil, strife, aggression and cruelty. This distancing from the every day world is an invitation for harmony and peace (Harte 36).”
In the heart of a zen garden lies patience for the work it takes to maintain and nurture the environment which is to stem from a love for the space. These vibrations transpire to the natural elements of the oasis which in turn thrive and reward the humans with a sense of bliss, tranquility and a sort of inner mental homeostasis.
Forest Bathing: Shinrin-Yoku
Various cultures from the Ancient Romans, to the Japanese and Norwegians have been long accolading a walk through the woods for its long list of human health benefits.
“Plants exude fleeting organic compounds called phytoncides, as a defense and communication mechanism that are also viewed as a restorative for humans to lower blood pressure, anger, and strengthen the immune system. Forest bathing shows signs of heightened cerebral activity and improved concentration. It lowers high counts of cortisol (Viumdel 42)”.
Scientists are starting to attribute forest bathing with an increase in parasympathetic nervous system function and a reduction in the activation of the sympathetic nervous system. Forest bathing can alleviate chronic physical pain by stabilizing autonomic nervous system function, enhance white blood cell activity which can potentially strengthen the immune system, and also potentially better control blood glucose levels (Viumdel 45).
Soil Microbiota
The human microbiome has been a topic of much speculation in recent years. Scientists have established that each person’s internal flora is fluidly influenced by genetics, lifestyle activities and diet. Two major factors lie in the fact that humans have spent tens of thousands of years evolving alongside their environmental microbiota and that gardening produces a multitude of edible, fibrous-rich food items.
“Changes in gut microbiota composition in urbanized regions have been linked to the rise of inflammatory and non-communicable diseases. Gardening remains the primary source of soil contact in the modern era (Brown 1).”
Studies are now being conducted to study the fecal samples of families that spent more than 30 minutes gardening per week. The highest proportion of soil bacteria found in participants at the peak of the season was 23% (Brown 6). The consensus among scientists is that a wider array of microbial species colonized within our gut can help potentially alleviate chronic conditions.
“Samples were dominated by Proteobacteria 30%, Actinobacteria 22%, and Bacteroidetes at 9.8%. LEfSe analysis revealed that gardening families had significantly greater abundances of Romboutsia, Terrisporobacter, Butyricicoccus, and Lachnospiraceae at peak season than before the gardening season. Over this time period, Romboutsia increased 77% and Terrisporobacter increased sixfold (Brown 5).”
Bacteroidetes are usually low in patients experiencing depression (Bruce 2), and did in fact increase almost 10% during peak growing season amongst participants. Actinobacteria help maintain the intestinal mucosal layer which can help reduce bodily inflammation, Romboutsia and Terrisporobacter help metabolize glucose and complex oligosaccharidal sugars, and Butyricicoccus and Lachnispiraceae presence reduces chronic conditions such as inflammatory bowel disease and colon cancer occurrence (Bruce 4). This data suggests that inhaling and ingesting soil microbiota can potentially reduce inflammation, aid with glucose regulation, and help maintain a healthy gut lining. The association between Bacteroidetes prevalence and lower rates of depression can also be potentially pivotal in the field of mental health. This study was published in 2022. Hopefully more studies will be done in various locations to try to replicate these promising results.
Five Senses Take Center Stage
Our senses dictate how we interpret the world and navigate our immediate surroundings. We use them to sense danger, to create beauty, meet our daily needs and to express ourselves artistically. In terms of vision, the human eye can distinguish the most number of shades stemming from the color green. The naked eye can see about one hundred hues of green pigments versus only a few dozen hues of every other color (Mencagli 7). Humans possess an innate attraction to nature sounds built into our “genetic matrix”. This spans across cultures and the various worldwide geographic regions (Mencagli 14). The physical act of touching soil also miraculously increases the secretion of serotonin (Park 5).
Olfaction is a powerful human attribute. For ages, herbs and fragrant flora held religious, spiritual or symbolic value. Scientists in Poland took it upon themselves to study restorative fragrance gardens as a possible means to improve emotional health (Krzeptowska 1). Respondents reported linking positive herb smell correlations with happy memories of family, vacations, childhood and travel. Their brain ascribed a positive correlation in their prefrontal cortex with the presence of lemon balm, lavender, mint, oregano and rosemary with personal anecdotes. This connection was then met with a reduction of stress and an elevation of mood (Krzeptowska 3).
Plants, fungi, bacteria and insects all produce scents that are low in molecular weight and are particularly volatile when they become gaseous. The chemical makeup is that of ten carbon atoms. Scientists coined these natural compounds: monoterpenes.
“The olfactory duct is the most direct way to reach the receptors of the central nervous system. This is why the effects of inhalation are so rapid. The natural action of monoterpenes is also expressed at the cerebral level, like stimulants or sedatives, anxiolytics and antidepressants, with positive effects on both memory and cognitive processes, as well as mood (Mencagli 80).”
Scientists have found that exposure to a high level of monoterpenes, especially in an environment such as a forest, lowered cortisol levels in saliva and reduced the amount of hemoglobin flowing to the prefrontal cortex of the brain (Mencagli 85). There was also a noted significant increase in anti-cancer proteins within lymphocytes and levels of adrenaline and noradrenaline drop in urine levels (Mencagli 88-89).
Neurotransmitters & Neural Plasticity
Research shows that the repetitive nature of weeding, pruning and water can enhance neural connections in the realm of memory, attention, cognition and creativity (Migala 1). Another study noted changes in brain chemistry in gardening participants and found significant changes in cognitive and immune function, as well as brand-new neural cell proliferation.
“Pathway analysis showed an uptick of tryptophan metabolism, kynurenine, and distinctive serotonin metabolites. Brain-derived neurotrophic factor levels (BDNF) in the gardening group increased. BDNF is present in hippocampus, vascular formation, permeability, and connective tissue changes. It can promote cell proliferation and growth as well as neuronal development and function (Park 4).”
Dr. Park and his team gathered their samples by drawing blood samples and utilizing gas chromatography techniques. They deduced that the physical aspect of gardening helps build muscle mass and aerobic endurance while reducing oxidative stress, inflammation, and depression. More specifically, the team was able to isolate their research to an entire regulatory line of metabolites correlated with tryptophan metabolism including serotonin, kynurenine, and idole derivatives, as well as organic acids such as lactic, pyruvic, and malic acid (Park 8).
“Abnormal conditions related to central nervous system (CNS) disease, including depression and schizophrenia are related to tryptophan metabolism. Serotonin plays an important role as a neurotransmitter and prominent role in brain development including cognition, emotion and pain sensitivity. Psychological abnormalities in depression and emotional expression have been linked to serotonin levels which showed a decreasing pattern. Pyruvic acid which is involved in the glycolysis process is catabolized from glucose and then passed to produce ATP. Metabolite is an important energy source in the brain and circulation system, and also maintains improvements in cognitive function and improves neuron survival. Memory, cognition and muscle ability are correlated with pyruvate and lactic acid (Park 9).”
The fact that not only an entire neural regulatory system is affected by gardening but that new nerve and cell growth is recorded, and increases are being noted in cortical and hippocampus function is pretty convincing research that more members of the medical community can hopefully embrace and possibly encourage gardening as protocol for their patients.
Negative Ions: Practice of Grounding
There is much discussion these days on modern society and the extent of positive ionization of the air within our cities. The earth’s surface is predominantly negative in charge, as is an open space where plants dwell. Human evolution took place in negative air ionization biospheres for hundreds of thousands of years (Mencagli 102-105).
“There is natural radioactivity on the ground level, waterways, water vapor, sun rays, thunderstorms, and chemical reactions produced in plant tissue by photosynthesis. Certain amount of energy causes molecules in the mixture of gases in the air to release an electron, which is immediately attracted to another molecule, giving it a negative charge and forming a negative ion (Mencagli 100-102)”.
Studies have shown correlations between negative ion exposure and a decrease in stress, mood disorders, and both physical and mental fatigue. Furthermore, scientists found that subjects had improved cognitive performance, better recovery from mental and physical exertion and normalization of blood pressure (Mencagli 107). On the contrary, positive ions have been found to accelerate aging and give rise to cellular oxidation (Mencagli 108)
Biomagnetics: The Power of Healing
The theory of biomagnetics states that urban gardening can be a reverent space of healing and recuperation simply because of the vibrational energy being given off by plants.
“Each plant is an antenna that vibrates and emits electromagnetic signals at frequencies that are in resonance with our organs, since our common biological systems are organized in an energetically similar way (Mencagli 127)”.
Quantum physics is starting to recognize that electromagnetic forces exist between objects and living things. There is interaction and transmission between structures and organic matter (Mencagli 121). Humans are submerged in the bioresonance influence of the sun, cycle of seasons and botanical behavior. (Mencagli 119).
“A bioenergetic garden is like a silent green concert where trees and plants are the energy instruments and the cells of our bodies are mesmerized listeners (Mencagli 141)”
Urban Gardening & Mental Health: Discussion
It is more important now than ever to integrate urban gardens into communities. Many individuals spend an average of 90% of their time indoors, usually coupled with a multitude of screens. City residents could integrate a sense of calm into their hectic schedules. Perhaps even employers could create green space initiatives that could work to decrease stressors and sympathetic nervous system activation.
The deep rooted evolutionary history of our cohabitation with plants solidifies the case that we should continue to try to maintain a relationship with them. Having contact with uncontaminated soil seems to be another variable that can benefit our health.
It would be beneficial to try to work urban farms into our cultural identity the same way the Buddhist monks created a space for zen gardens and forest bathing was encouraged in cultures worldwide. Rooted practices become habitual and generational. Memories transform into cognitive neurotransmitter signals and the positive correlation remains strong.
Mental health encompasses environmental influences, some of which we can control. This news is empowering and the future can be optimistic. Soil spores can be healers, sounds and colors can elicit calmness and negative ions can aid in restoring harmony to our positive ion-abundant lives.
Exposure to plants and forming affinities with our favorites is pivotal to mental health. Just like certain herbs carry spiritual, religious or cultural significance, by deepening our relationship with plants, we form allies and are more likely to nurture them and have them proliferate around us.
Early exposure to urban gardens seems to be key. This establishes links with memory, positive associations with hippocampus pathways, a more diverse microbiome from a young age and a greater likelihood to continue to nourish the connection as one ages.
Further studies need to be conducted to cross-check the findings of the microbiota soil colonies and neurotransmitter frequencies of gardening communities. There are so many variables that might not be related to gardening at all that can skew the results. While the findings are exciting, this field of study is still novel and needs further review to continue to unlock the plant pieces of the puzzle.
Concluding Thoughts
The effect of plants on human mental health runs deep and is multi-dimensional—from brain chemistry to sensory code.. and even biomagnetics. The hope is that these extensive positive correlations between human mental health and exposure to plants are recognized by more primary care physicians who can help create protocols for their patients that encourage urban agriculture. Ideally more funding would be made available to study the field more extensively and to cross test some of the promising results these scientists were able to deduce.
Works Cited:
Bailey, Fran. The Healing Power of Plants. 1st ed., Sterling Publishing Co., Inc, 2019.
Brown, M.D., Shinn, L.M., Reeser, G. et al. Fecal and soil microbiota composition of gardening and non-gardening families. Sci Rep 12, 1595 (2022). https://doi.org/10.1038/s41598-022-05387-5
Bruce, Lindsay, and Sarah Lane Ritchie. "THE PHYSICALIZED MIND AND THE GUT‐BRAIN AXIS: TAKING MENTAL HEALTH OUT OF OUR HEADS: with Gillian K. Straine and Mark Harris,“Mental Well‐Being, Neuroscience, and Religion: Contributions from the Science and Religion Forum”; Fraser Watts,“Theology and Science of Mental Health and Well‐Being”; Lindsay Bruce and Sarah Lane Ritchie,“The Physicalized Mind and the Gut‐Brain Axis: Taking Mental Health Out of Our Heads”; Jaime Wright,“In the Beginning: The Role of Myth in Relating Religion, Brain Science, and ...." Zygon® 53.2 (2018): 356-374.
Gascon, Mireia, et al. "Feasibility of collection and analysis of microbiome data in a longitudinal randomized trial of community gardening." Future Microbiology 15.8 (2020): 633-648.
Harte, Sunniva. Zen Gardening. 1st ed., Stewart, Tabori and Chang, 1999.
Krzeptowska-Moszkowicz, Izabela, Łukasz Moszkowicz, and Karolina Porada. "Urban Sensory Gardens with Aromatic Herbs in the Light of Climate Change: Therapeutic Potential and Memory-Dependent Smell Impact on Human Wellbeing." Land 11.5 (2022): 760.
Mencagli, Marco and Marco Nieri. The Secret Therapy of Trees: Harness the Healing Energy of Forest Bathing and Natural Landscapes. 1st ed., Penguin Random House, 2019.
Migala, Jessica. “Your Body On… Gardening.” Women’s Health, vol. 13, no. 4, May 2016, p. 108. EBSCOhost, https://search-ebscohost-com.proxy.library.nyu.edu/login.aspx?direct=true&db=rgm&AN=114008296&site=eds-live.
Park, Sin-Ae, et al. "Metabolite profiling revealed that a gardening activity program improves cognitive ability correlated with BDNF levels and serotonin metabolism in the elderly." International journal of environmental research and public health 17.2 (2020): 541.
Park, Sin-Ae, et al. "Benefits of gardening activities for cognitive function according to measurement of brain nerve growth factor levels." International journal of environmental research and public health 16.5 (2019): 760.
Viumdal, Jorn. Skogult: Norwegian Secrets for Bringing Natural Air and Light into Your Home and Office to Dramatically Improve Health and Happiness. 1st ed., Harper Design, 2019.