School-Based Gardening Intervention Benefits Metabolic Outcomes in Young Children

Jaimie N. Davis, PhD, RD

A school-based gardening, nutrition, and cooking intervention may improve metabolic parameters in elementary schoolchildren, reports new research from JAMA Network Open.

The secondary analysis of the Texas Sprouts randomized controlled trial (RCT) indicates the intervention improved glycemic control and reduced low-density lipoprotein-cholesterol (LDL-C) in the mainly low-income and racially diverse population of children.

“The current findings suggest that small increases in dietary fiber and vegetable intake and reductions in added sugar intake may have combined effects on lowering LDL-C and improving glucose control,” wrote study author Jaimie N. Davis, PhD, RD, Department of Nutritional Sciences, College of Natural Sciences, University of Texas at Austin.

The past four decades has seen a significant increase in the prevalence of childhood obesity, showing an association between low socioeconomic status and an increase in overweight or obesity. Evidence-based interventions may be needed to improve fruit and vegetable intake and reduce obesity-related cardiometabolic diseases in low-income children from minoritized racial and ethnic groups.

Most school-based interventions that examined the effects of RCTs on metabolic outcomes used a multicomponent approach of nutrition, physical activity, and behavior modifications. However, no cluster RCT has been conducted to assess the effects of an in-school garden-based intervention on metabolic health outcomes.

The school-based cluster RCT was conducted over 3 years from 2016 to 2019. Sixteen elementary schools were randomly assigned either Texas Sprout intervention (8 schools) or to delayed intervention (control, 8 schools). The schools were majority Hispanic children (>50%), majority of children (>50%) were participating in the free and reduced-price lunch (FRL) program, a location within 60 miles of central Austin, Texas, and no existing garden or gardening program.

Full-time experienced and trained nutrition and garden educators taught 18 one-hour Texas Sprouts lessons separately to each third to fifth grade class throughout the school year as part of the normal school day. The control schools received a delayed intervention in the year after completion of the posttesting for the original intervention.

At baseline and post-intervention (9 months), investigators used a survey to collect demographic measures including measured height, weight, body mass index parameters, glucose, insulin, homeostatic model assessment of insulin resistance, and a lipid panel via an optional fasting blood draw.

Of the 4239 eligible children, 3302 (78%) consented to be in the study and 3137 (74%) completed baseline clinical measures (height, weight, and BMI parameters) and child surveys. A total of 1104 consented children (or 33% of those enrolled) completed the optional baseline blood draw and 695 children who participated in the baseline blood draw (63%) also gave blood at the post intervention follow-up.

The final analytic sample was made up of 307 boys (44%), had a mean age of 9.28 years, while 480 (69%) were Hispanic, and 452 (65%) were eligible for free and reduced-price lunch programs.

Compared with the children in the control schools, those in the Texas Sprouts intervention had a 0.02% reduction in mean HbA1c (95% CI, 0.03% - 0.14%; P = .005) and a 6.40 mg/dL reduction in mean LDL-C (95% CI, 3.82 - 8.97 mg/dL; P = .048). Investigators cited no intervention effects on glucose, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), or other lipid parameters.

“These findings provide direct evidence to help encourage policy makers, administrators, and school district personnel to adopt and/or support garden-based learning into elementary schools,” Davis added.

The study, “Effects of a School-Based Nutrition, Gardening, and Cooking Intervention on Metabolic Parameters in High-risk Youth: A Secondary Analysis of a Cluster Randomized Trial,” was published in JAMA Network Open.