For years, Jill Litt, PhD, an assistant professor in the Department of Environmental Studies at the University of Colorado\ Boulder had been hearing from friends and colleagues about how much better they feel when they have a garden.
So, she decided to explore this hypothesis scientifically.
Litt set out to build a clinical trial that looked at the relationship between gardening and good health. She reached out to multiple scientific organizations trying to convince them to fund her pursuit.
What she got in return was mostly skepticism.
But Litt refused to give up. And eventually, the American Cancer Society gave her the funding she needed.
Litt’s studyTrusted Source, published last week in The Lancet Planetary Health journal, is the first randomized, controlled trial of community gardening and its impact on public health.
The research looked at whether a community gardening intervention could reduce common health risks in an adult population that is diverse in terms of age, ethnicity, and socioeconomic status.
“I felt that if we improved diet and reduced stress and anxiety, it would impact inflammation and control weight gain, too,” Litt told Healthline.
She added that she was looking for results that were “not pharma-driven.”
The findings suggested that those who started gardening ate more fiber and got more physical activity — two known ways to reduce the risk of cancer and chronic diseases.
The research also showed that community gardening can provide a “nature-based solution, accessible to a diverse population including new gardeners, to improve wellbeing and important behavioral risk factors for non-communicable and chronic diseases,” the study authors concluded.
Litt, who saw levels of stress and anxiety significantly decrease among the 291 participants, said the findings provide solid evidence that community gardening can play an important role in preventing cancer, chronic diseases, and mental health disorders.
For the trial, Litt recruited non-gardening adults from the Denver area whose average age was 41. More than half came from low-income households. A third of them were Hispanic.
Half were assigned to the community gardening group and the other half to a control group that was asked to wait one year to start gardening.
The gardening group received a free community garden plot, some seeds and seedlings, and an introductory gardening course.
Both groups took periodic surveys about their nutritional intake and mental health, underwent body measurements, and wore activity monitors.
By fall, those in the gardening group were eating an average of 1.4 grams more fiber per day than the control group— an increase of about 7%.
The authors explained that fiber exerts a significant effect on inflammatory and immune responses, influencing everything from how food is metabolized to how healthy our gut microbiome is to how susceptible we are to diabetes and certain cancers.
While experts recommend about 25 to 34 grams of fiber per day, the average adult in the United States consumes 10 to 15 grams daily.
“An increase of one gram of fiber can have large, positive effects on health,” James Hebert, ScD, a study author and the director of the University of South Carolina’s cancer prevention and control program, said in a press statement.
The gardening group also increased their physical activity levels by about 42 minutes per week.
Study participants also saw their stress and anxiety levels demonstrably decrease, with those who came into the study most stressed and anxious seeing the greatest reduction in mental health issues.
The study authors also reported that even novice gardeners can reap measurable health benefits from the pastime in their first season. As gardeners have more experience and enjoy greater yields, Litt predicts such benefits will increase.
The researchers concluded that “community gardening can provide a nature-based solution, accessible to a diverse population including new gardeners, to improve wellbeing and important behavioral risk factors for non-communicable and chronic diseases.”
Rafaela Crevoshay, a crop adviser and horticulturist in San Diego who jokingly said she prefers the term “soil guru,” is not surprised by the study’s findings.
She said that gardens are healing, especially organic gardens.
“The soil historically has not been a focus of the cancer community, but the medical research community in the last 10 or so years has discovered the human microbiome and the soil microbiome and their impact on health,” Crevoshay told Healthline.
Teresa Stivers, the chief executive officer of Walden Family Services in San Diego, a foster care, adoption, and youth services agency, was not part of the study.
However, she started a garden when she had long COVID in 2020, and she says it has greatly improved her health.
“It’s been amazing for my mental health. If it’s good for cancer, too, that is an added bonus. Not to mention all the fresh, unprocessed food we are eating,” said Stivers, whose long COVID symptoms included fatigue, tinnitus, and vertigo.
“We have two mental health clinics where I work, so I knew to start therapy and find activities to help me recover,” she told Healthline.
“Gardening was at the top of my list. My husband built a large raised planter and we traveled to farmer’s markets and nurseries throughout San Diego. We planted herbs, vegetables, fruit trees, and more, she said.
They also erected hummingbird feeders, bought native milkweed to attract monarchs, and intalled a bee box.
“We spent more time outside and harvesting from our garden, which has brought me immense joy. It also changed how I eat, as I am more aware of using fresh, organic ingredients,” Stivers said.
“I’m hoping it will positively affect my health, especially now that I’ve heard about this study. My late father and his side of the family have had multiple cancers, which has always been a concern for me.”
Litt said she hopes the findings in this study will encourage health professionals, policymakers, and land planners to “look to community gardens, and other spaces that encourage people to come together in nature, as a vital part of the public health system.”
The evidence of their effectiveness, she said, is indisputable.
