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ORIGINAL RESEARCH article

Front. Public Health

Sec. Environmental Health and Exposome

Nature-based interventions reduce physiological stress in children with chronic illnesses: evidence from salivary biomarkers

Provisionally accepted
Francisco Díaz MartínezFrancisco Díaz Martínez1,2Miguel Felipe Sánchez-SaucoMiguel Felipe Sánchez-Sauco1,2Esteban Orenes-PiñeroEsteban Orenes-Piñero3Maria Jose Hernández-VeraMaria Jose Hernández-Vera2Francisco Robledano AymerichFrancisco Robledano Aymerich4Luz ClaudioLuz Claudio5Juan Antonio Ortega-GarcíaJuan Antonio Ortega-García2,3,6*
  • 1Institute for Biomedical Research of Murcia IMIB-Arrixaca, Murcia, Spain
  • 2Unidad de Salud Medioambiental Pediatrica de la Región de Murcia (España), Murcia, Spain
  • 3Instituto Murciano de Investigacion Biosanitaria Virgen de la Arrixaca, Murcia, Spain
  • 4Universidad de Murcia Departamento de Ecologia e Hidrologia, Murcia, Spain
  • 5Icahn School of Medicine at Mount Sinai Department of Environmental Medicine and Public Health, New York, United States
  • 6Departamento de Pediatria, Universidad de Murcia, Murcia, Spain

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Contact with nature is increasingly recognized as a determinant of public health, yet little objective evidence exists for its benefits in children with chronic illnesses. This quasi-experimental study assessed the short-term effects of a forest-based intervention on stress-related salivary biomarkers in 52 children aged 8–17 years, including cancer survivors and those with neurodevelopmental disorders, alongside their healthy siblings. Participants engaged in a 2.5-hour guided immersion in a Mediterranean forest, with saliva samples collected before and after the activity to measure cortisol, alpha-amylase, and immunoglobulin A. Significant reductions in cortisol and alpha-amylase were observed at the group level, indicating acute stress relief. Subgroup analyses showed notable decreases in cortisol and immunoglobulin A among children with neurodevelopmental disorders, and in alpha-amylase among cancer survivors. These findings provide novel biomarker-based evidence that brief nature exposure can reduce physiological stress in vulnerable paediatric populations. The results highlight the importance of integrating accessible natural environments into healthcare and community programmes to promote health, resilience, and well-being. This study was approved by the Ethics Committee of the Hospital Clínico Universitario “Virgen de la Arrixaca” on June 29, 2021 (CEIC Code, 2021-6-10-HCUVA).

Keywords: Forest environments, Physiological benefits, Children, scientific evidence, contactnature, salivary cortisol

Received: 03 Sep 2025; Accepted: 25 Nov 2025.

Copyright: © 2025 Díaz Martínez, Sánchez-Sauco, Orenes-Piñero, Hernández-Vera, Robledano Aymerich, Claudio and Ortega-García. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Juan Antonio Ortega-García

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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