Previous studies had shown that community gardeners provide both nutritional and social benefits to neighborhoods, lead author Cathleen Zick explained. "But until now, we did not have data to show a measurable health benefit for those who use the gardens."
The Utah team used BMI (body mass index) to measure how close or far people were to their ideal body weight. BMI is a calculation based on your height and weight; it is commonly used to screen for obesity, overweight or underweight. A healthy BMI for a typical adult ranges from 18.5 to 24.9. BMI is not a good measurement for intense athletes or particularly muscly people.
The researchers used unique administrative data to assess the relationship between community gardening and health outcomes. They compared a typical community gardener's BMI and likelihood of being obese/overweight with three control groups:
- Unrelated people from the same neighborhood group - these people shared the same physical environment, including how near local shops and stores were, economic statuses, and walkability
- Same sex siblings group - in order to factor in family influences, such as genetics, diet and exercise
- Gardeners' spouses group - these people share similar food choices and lifestyles, including the benefits of the food grown in the community garden
People who use community gardens are less likely to be overweight or obese
Zick and team found that:
Compared to the unrelated people from the same neighborhood group
- Female community gardeners' average BMI was 1.84 lower than the average for their neighborhood, i.e. 11 pounds (4.98 kilos) leaner for a 5 ft 5 inch tall woman
- Male community gardeners' average BMI was 2.36 lower than the average for their neighborhood, i.e. 16 pounds (7.25 kilos) leaner for a 5 ft 10 inch tall man
- Female community gardeners were 46% less likely to be overweight/obese than the average woman in their neighborhood
- Male community gardeners were 62% less likely to be overweight/obese than their average male neighbors
- Female community gardeners had a BMI 1.88 lower than their sisters
- Male community gardeners had a BMI 1.33 lower than their brothers
- Spouses of male or female community gardeners were no more likely to become obese/overweight than their community gardening loved ones. Researchers said this is not surprising because they probably benefited from eating garden vegetables and helping out with gardening activities.
Compared to the same sex siblings group
Compared to gardeners' spouses group
"These data are intriguing, although they were drawn from participants in a single community gardening organization in Salt Lake City and may not apply broadly until more research is done. However, as the percentage of Americans living in urban areas continues to grow, this initial study validates the idea that community gardens are a valuable neighborhood asset that can promote healthier living.
That could be of interest to urban planners, public health officials and others focused on designing new neighborhoods and revitalizing old ones."
"We know obesity is costly. This study begins to shed light on the costs and benefits of the choices families make about eating and physical activity.
Future research with controlled, randomized field studies across a range of communities are needed to further advance our understanding of the role gardening can play in healthy lives."
In the April 2007 issue of the Journal of the American Dietetic Association, Debra Haire-Joshu, Ph.D., director of Saint Louis University's Obesity Prevention Center wrote "Whether a food is homegrown makes a difference. Garden produce creates what we call a 'positive food environment'."