A 15-day pilot biodiversity intervention with horses in a farm system leads to gut microbiome rewilding in 10 urban Italian children.

Overview

• This study investigated how daily interaction with horses over 15 days affects the gut microbiome of urban children in Italy.
• The research found that spending time with horses in a farm environment led to beneficial changes in the children’s gut bacteria, suggesting a “rewilding” effect through microbial exchange.

Research Objective and Setting

• To explore whether probiotic exchange with natural ecosystems, specifically through interaction with horses, can shape the human gut microbiome (GM) of urban children.
• Ten Italian children living in urban areas participated in a 15-day pilot intervention at an educational farm.
• The children spent nearly 10 hours daily interacting closely with horses, providing a high level of exposure to animal-associated microbes.

Methods and Sample Collection

• Gut microbiome samples from the children were collected before and after the 15 days of horse interaction.
• Microbial analyses were performed using:
  • Metabarcoding sequencing to identify microbial taxa
  • Shotgun metagenomics to capture the full genetic content of microbes and assess functional potential
• Microbiomes of the horses (skin, oral, and fecal) were also sampled to understand the possible microbial sources.
• Targeted metabolomic analysis was conducted on the children’s feces to measure levels of short-chain fatty acids (SCFAs), which are key beneficial metabolites produced by the gut microbiota.

Key Findings: Gut Microbiome Changes in Children

• Interaction with horses led to an increase in diversity of the gut microbiome in children, a generally beneficial trait linked to gut health.
• There was enhanced production of butyrate, a beneficial SCFA known for supporting gut lining integrity and anti-inflammatory effects.
• Specific health-promoting bacterial species increased in abundance, including:
  • Known butyrate producers such as Faecalibacterium prausnitzii and other related species
  • A species within the order Christensenellales, associated with healthy gut function and leanness
• Increases were seen in bacterial taxa involved in processing dietary polyphenols into beneficial metabolites, including genera such as Akkermansia, Blautia, and Roseburia.
• No rise in harmful microbial traits was observed, such as toxin genes, indicating the safety of this microbial exposure.

Significance and Implications

• The study provides preliminary evidence that close contact with animals in a farm environment can “rewild” or beneficially enrich the human gut microbiome.
• This probiotic exchange between horses and children aligns with the One Health concept, which recognizes the interconnectedness of human, animal, and environmental health.
• Findings support the potential of natural ecosystem exposures as a complementary approach to promote gut health, especially in urbanized populations that often have reduced microbial diversity.
• The pilot nature suggests that larger and more systematic studies are needed to fully understand the complexities and health outcomes of microbiome rewilding.

Conclusion

• The 15-day farm-based interaction with horses positively shaped the gut microbiome of urban Italian children by increasing diversity and beneficial bacteria and metabolites.
• The pilot study suggests natural animal contact could be a valuable strategy to enhance gut microbial health in children living in urban environments.
• Future research is necessary to confirm these results and explore the long-term impact and potential clinical benefits of such microbiome interventions.