In a courtroom trial, multiple lines of evidence increase the likelihood that the outcome and verdict will be correct. Likewise, in scientific research, various lines of evidence generated using different approaches, methods, and conducted by independent laboratories and investigators increase the probability that the findings and outcomes will be correct.
That gardening treatments can provide therapeutic benefits has been demonstrated experimentally many times over a wide range of demographic groups, health conditions, and symptoms. However, what if a different approach was taken? Would the results of a large population survey of people’s physical activity (PA) and dietary habits support the positive therapeutic outcomes of gardening found in experimental treatment studies or find no evidence of benefits?
Susan Veldheer and colleagues1 initiated their study to compare the health outcomes of categorized gardeners, non-exercisers, and exercisers from a national survey of older adults 65 years and up for cardiovascular disease, hyperlipidemia, hypertension, high BMI, diabetes, stroke, myocardial infarction, dietary intake, mental and physical health, and 10-year mortality risk.
The researchers analyzed survey data of the de-identified publicly available data from the 2019 Behavioral Risk Factor Surveillance System (BRFSS) managed by the CDC for 146,047 participants 65 and over. PA was evaluated based on the question: “In the past month, other than your regular job, did you participate in any physical activity? (yes/no).” Individuals were classified as gardeners if they reported PA and listed gardening first or second as the most time spent doing PA during the past month. Those who reported PA but did not list gardening first or second were classified as exercisers. Respondents who did not report any PA were classified as non-exercisers. Additional steps taken to define the three groups more precisely can be found in the published paper. The final distribution of participants in the three groups was: gardeners 14,903 (10%), non-exercisers 45,007 (31%), and exercisers 86,190 (60%).
Dietary intake of fruits and vegetables was based on six items: fruit, fruit juice, leafy green vegetables, potatoes, fried potatoes, and other vegetables, and tallied as the number per day. Self-reported health outcomes were tabulated and dichotomized as lower or higher values.
Statistical differences between groups were assessed using parametric and nonparametric t-tests. For analysis of categorical data, chi-square tests were used. Please see the paper for more details and information on the statistical analyses.
Gardeners were more likely to be women, non-Hispanic white, and married than exercisers and non-exercisers. Gardeners and exercisers tended to have more education beyond high school than non-exercisers. Gardeners spent more total PA time than exercisers, and a greater percentage of gardeners than exercisers met recommended aerobic PA levels.
What were the outcomes of the comparisons of the three groups? Were there any differences? Gardeners had lower odds of experiencing all adverse health outcomes than non-exercisers and higher odds of consuming 5 or more fruits and vegetables daily. This included lower odds of reporting cardiovascular disease, stroke, heart attack, diabetes, and poorer mental and physical health status. Not surprisingly, gardeners had a much lower adjusted odds ratio than non-exercisers for high 10-year mortality risk. Therefore, one might conclude that, on average, gardeners live longer and have fewer health issues than non-exercisers.
While the health outcomes for gardeners and exercisers were not different overall, female gardeners were less likely to report stroke, diabetes, poor physical health status, or high 10-year mortality. Male gardeners were less likely to report cardiovascular disease and diabetes than exercisers.
The authors conclude from the study findings that engaging in gardening PA is correlated with better outcomes in older adults for cardiovascular disease risk, diabetes, and mental health status.
Therefore, the findings in the present study analyzing large-scale survey data align and strongly support past treatment-based experimental studies demonstrating therapeutic benefits from engaging in gardening activities. Like in the courtroom, multiple lines of corroborating evidence strengthen the odds that the findings and verdicts are robust and correct.
From a public health perspective, what other low-tech, non-pharmacological, low-cost intervention could so effectively address three of the most critical health challenges confronting today’s society?
1Veldheer, S., Tuan, W.J., Al-Shaar, L., Wadsworth, M., Sinoway, L., Schmitz, K.H., Sciamanna, C., Gao, X. (2023). Gardening Is Associated with Better Cardiovascular Health Status Among Older Adults in the United States: Analysis of the 2019 Behavioral Risk Factor Surveillance System Survey. Journal Academy Nutrition Dietetics, 123(5):761-769.e3.
https://doi.org/10.1016/j.jand.2022.10.018
Charles Guy, Emeritus and Courtesy Professor
Department of Environmental Horticulture, University of Florida
Steering Committee, Wilmot Botanical Gardens, University of Florida