Effects of a School-Based Nutrition, Gardening, and Cooking Intervention on Metabolic Parameters in High-risk Youth: A Secondary Analysis of a Cluster Randomized Clinical Trial

IMPORTANCE: Although school-based gardening programs for children have consistently been shown to improve dietary behaviors, no cluster randomized clinical trial (RCT) has evaluated the effects of a school-based gardening intervention on metabolic outcomes. OBJECTIVE: To evaluate the effects of a school-based gardening, nutrition, and cooking intervention (Texas Sprouts) on changes in metabolic outcomes in elementary schoolchildren. DESIGN, SETTING, AND PARTICIPANTS: This study was a secondary analysis of a cluster RCT, conducted over 3 years from 2016 to 2019, at low-income elementary schools with majority Hispanic students in the greater Austin, Texas, area. Data were analyzed from January to August 2022. INTERVENTIONS: Texas Sprouts was 1 school year long (9 months) and consisted of (1) Garden Leadership Committee formation; (2) a 0.25-acre outdoor teaching garden; (3) 18 student gardening, nutrition, and cooking lessons taught by trained educators throughout the school year; and (4) 9 monthly parent lessons. The delayed intervention was implemented the following academic year and received an identical intervention. MAIN OUTCOMES AND MEASURES: The following measures were obtained at baseline and postintervention (9 months): demographics via survey; measured height, weight, and body mass index parameters; and glucose, insulin, homeostatic model assessment of insulin resistance, and a lipid panel via an optional fasting blood draw. RESULTS: Sixteen elementary schools were randomly assigned to either Texas Sprouts intervention (8 schools) or to delayed intervention (control, 8 schools). A total of 3302 children (aged 7-12 years) were enrolled in Texas Sprouts, and fasting blood samples were obtained from 1104 children (or 33% of those enrolled) at baseline. The final analytic sample included 695 children (307 boys [44.17%]; mean [SE] age, 9.28 [0.04] years; 480 Hispanic children [69.02%]; 452 [65.03%] eligible for free or reduced lunch) with complete demographic data and baseline and postintervention (9-month) fasting blood draws. Compared with control schools, children from Texas Sprouts schools had a 0.02% reduction in mean hemoglobin A(1c) (95% CI, 0.03%-0.14%; P = .005) and a 6.40 mg/dL reduction in mean low-density lipoprotein cholesterol (95% CI, 3.82-8.97 mg/dL; P = .048). There were no intervention effects on glucose, insulin, homeostatic model assessment of insulin resistance, or other lipid parameters. CONCLUSIONS AND RELEVANCE: In this cluster RCT, Texas Sprouts improved glucose control and reduced low-density lipoprotein cholesterol in high-risk youth. These findings suggest that elementary schools should incorporate garden-based interventions as a way to improve metabolic parameters in children. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02668744