"Play&Grow” is a family-oriented environmental education program developed by the University of Hong Kong to reconnect preschool children to nature and promote positive changes in health behaviors and outcomes. Previous evaluations of the program have found it to be effective in encouraging healthy lifestyle behaviors in families with preschoolers. The aim of this study was to investigate the impact of the Play&Grow program on the intestinal microbiome, gut serotonin level, and the psychological well-being of 2- to 5-year-old children. Intestinal microbiota support digestive and immune system health and produce mood-regulating chemicals like serotonin.
The study involved 54 preschool children (age 2-5) in Hong Kong. The children were randomly assigned to an intervention group or control group. Children in the intervention group (N=27) participated in a once-a-week Play&Grow program over a period of 10 weeks. The sessions were conducted in public parks and included guided nature-related activities with “hands-on” experiences with materials found in nature. The activities were specifically designed to give participants an opportunity to come into contact with the microbiome of the natural environment. Families were given additional nature-related “homework” to further increase their interaction with the natural environment and its bacteria. Examples of homework included collecting natural materials, making nature art, and growing plants. Children in the control group (N=18) did not participate in the Play&Grow program. Assessments were conducted on both groups of children prior to and after the 10-week intervention. Assessments included a psychosocial measurement, an assessment for connectedness to nature, a serotonin measurement, and gut microbiota analysis.
Children in the intervention group were significantly more connected to nature after participating in the Play&Grow program. They also scored lower in overall perceived stress levels and showed significantly increased prosocial behavior post-intervention. Behavior changes were particularly noted in the reduced frequency of anger. Prior to intervention, there was no significant difference in microbial community structure between the intervention group (IG) and the control group (CG). After the intervention, however, there were clear differences between the two groups. Children in the IG showed changes in their gut microbiota; children in the CG did not. The difference in gut microbiota levels was attributed to several factors: completion of the Play&Grow intervention, serotonin levels, and anger frequency. Children in the IG with lower perceived stress scores exhibited significantly higher gut microbiota richness.
These findings indicate that the Play&Grow program significantly improved the overall perceived stress and prosocial behavior of the participating preschool children. The program was also successful in modulating the microbiome in the IG after regular exposure to nature over a ten-week period. These findings suggest that exposure to bacteria in natural environments could be beneficial to behavioral outcomes for young children. This possibility warrants further investigation.
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