Gardening may help reduce cancer risk, boost mental health

• A new study shows that people who work in community gardens receive various health benefits that may help reduce the risk of chronic diseases like cancer and can improve mental health.
• The randomized controlled trial involved 145 people who never gardened before and tracked their physical and mental health during and after a growing season.
• Participants consumed more fiber, got more exercise, and felt more connected and less anxious as a result of their community gardening experience.

Participating in community gardening reduces the risk of developing serious illnesses, including cancer and mental health disorders, according to a recent study.

Researchers at the University of Colorado Boulder (CU Boulder) have demonstrated that people receive multiple health-promoting benefits from community gardening.

Gardeners increased their intake of fiber by eating more fresh produce, got more exercise tending a garden, and felt more connected socially, all of which are protective factors against cancer, mental health issues, and various chronic illnesses.

Previous observational studies have suggested that gardening, in general, may deliver some of these benefits, but the CU Boulder study is the first randomized controlled trial (RCT) investigating the benefit of gardening, and community gardening in particular.

The study is published in The Lancet Planetary Health.

Beginners benefit from gardening

The researchers recruited 291 adults who had not gardened before. Individuals averaged 41.5 years of age, and 34% identified as Hispanic. Of the participants, 18% were male (52 participants), and half came from lower-income households.

The researchers conducted three gardening waves spanning 1 year each and beginning in May, just after the last frost in Denver and Aurora, CO, where the gardens were located. Half of each wave’s participants gardened, and half did not, serving as a control group.

Each participant received an introductory gardening course from Denver Urban Gardens and was allocated a standard, 10-square meter community garden plot, as well as seeds and seedlings.

The same was offered to the control-group individuals as compensation for delaying their gardening for the course of the study.

Lead study author Jill S. Litt, Ph.D., professor of environmental studies at CU Boulder, told Medical News Today that each participant spent an average of about 90 minutes a week gardening and visited their garden at least twice during the week.

“We found that being new to gardening was not a barrier to being successful at gardening, as our study only included new gardeners,” Dr. Litt said.

Gardening promotes healthy behaviors

Researchers assessed participants’ health before the study and group assignment, at harvest time, and the following winter. Individuals completed surveys regarding stress, anxiety, and diet and wore thigh-mounted accelerometers for 7 days at each assessment.

In the study, the researchers found that gardeners consumed slightly more dietary fiber than the control group, although still below the recommended level of 25–38 grams per day. They also exercised approximately 5 minutes more at harvest time than the control group.

“I think it’s a great study, looking at just the logistics of how they did it,” Rebecca Crane-Okada, Ph.D., R.N., advanced oncology nurse and professor of oncology at St. John’s Cancer Institute in Santa Barbara, CA, not involved in the study, told MNT. “It was a very complicated study to implement.”

Dr. Litt said the study addressed an existing research gap since smaller observational studies suggesting a link to better health could not determine if gardening led to a more healthy lifestyle or if it was the other way around.

She noted the study showed “that a holistic intervention such as community gardening can affect multiple outcomes — fiber, moderate-to-vigorous physical activity — and psychosocial health — stress and anxiety — in an acceptable and affordable way, for people of different social, economic, and demographic backgrounds.”

Gardening improves physical and mental health

Dr. Litt noted that gardening addresses multiple factors that are important for reducing the risk of chronic disease and promoting overall health.

According to Dr. Crane-Okada, community gardening provides a chance to address known “modifiable risk factors” for diseases such as:

• cancer
• high blood pressure
• type 2 diabetes

Denise Dillon, Ph.D., associate professor of psychology at James Cook University in Singapore, was not involved in the study but has published previous research on the mental health benefits of community gardening.

“In our research, participants who engaged in community gardening scored higher on personal subjective wellbeing and resilience than did participants who gardened alone at home or those who engaged in non-gardening, group outdoor activities, despite reporting similar levels of perceived stress.”

– Denise Dillon, Ph.D., psychology professor

Dr. Dillon added there’s “ample evidence from across a number of research paradigms to demonstrate benefits of direct exposure to natural environments for the purpose of restoration, whether physiological or psychological.”

Benefits of community gardening

There are thousands of urban community gardens in the United States.

Portland, OR, for instance, has 4.45 community gardens per 1,000 people, and such gardens are not restricted to temperate regions — St. Paul, MN, has the second-greatest density of community gardens in the U.S., with 3.84 gardens per 1,000 people.

Dr. Crane-Okada credited the benefits of community gardening to being outside in nature and fostering a connection to the earth. She noted that physical activity is required to prepare, nurture, and harvest a garden and that being a part of a community benefits mental well-being.

People who have been diagnosed with a chronic disease like cancer can also benefit psychologically from time spent working in a community garden, Dr. Crane-Okada said.

“The nature of gardening, usually outdoors, involves physical activity, a focus on something outside oneself — hence can also be a mindful activity — may be done in community, as in this study, which can serve as an additional social support,” she concluded.

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