Impact of outdoor nature-related activities on gut microbiota, fecal serotonin, and perceived stress in preschool children: the Play&Grow randomized controlled trial

Christensenella minuta mitigates behavioral and cardiometabolic hallmarks of social defeat stress

Psychological stress during early development and adolescence may increase the risk of psychiatric and cardiometabolic comorbidities in adulthood. The gut microbiota has been associated with mental health problems such as depression and anxiety and with cardiometabolic disease, but the potential role of the gut microbiota in their comorbidity is not well understood. We investigated the effects and mode of action of the intestinal bacterium Christensenella minuta DSM 32891 on stress-induced mental health and cardiometabolic disturbances in a mouse model of social defeat stress. We demonstrate that administered C. minuta alleviates chronic stress-induced depressive, anxiogenic and antisocial behavior. These effects are attributed to the bacterium's ability to modulate the hypothalamic-pituitary-adrenal axis, which mediates the stress response. This included the oversecretion of corticosterone and the overexpression of its receptors, as well as the metabolism of dopamine (DA) and the expression of its receptors (D1, D2L and D2S). Additionally, C. minuta administration reduced chronically induced inflammation in plasma, spleen and some brain areas, which likely contribute to the recovery of physical and behavioral function. Furthermore, C. minuta administration prevented chronic stress-induced cardiovascular damage by regulating key enzymes mediating liver fibrosis and oxidative stress. Finally, C. minuta increased the abundance of bacteria associated with mental health. Overall, our study highlights the potential of microbiota-directed interventions to alleviate both the physical and mental effects of chronic stress.

The influence of pre- and postnatal exposure to air pollution and green spaces on infant's gut microbiota: Results from the MAMI birth cohort study

BACKGROUND

Animal and human studies indicate that exposure to air pollution and natural environments might modulate the gut microbiota, but epidemiological evidence is very scarce.

OBJECTIVES

To assess the potential impact of pre- and postnatal exposure to air pollution and green spaces on infant gut microbiota assembly and trajectories during the first year of life.

METHODS

MAMI ("MAternal MIcrobes") birth cohort (Valencia, Spain, N = 162) was used to study the impact of environmental exposure (acute and chronic) on infant gut microbiota during the first year of life (amplicon-based 16S rRNA sequencing). At 7 days and at 1, 6 and 12 months, residential pre- and postnatal exposure to air pollutants (NO2, black carbon -BC-, PM2.5 and O3) and green spaces indicators (NDVI and area of green spaces at 300, 500 and 1000 m buffers) were obtained. For the association between exposures and alpha diversity indicators linear regression models (cross-sectional analyses) and mixed models, including individual as a random effect (longitudinal analyses), were applied. For the differential taxon analysis, the ANCOM-BC package with a log count transformation and multiple-testing corrections were used.

RESULTS

Acute exposure in the first week of life and chronic postnatal exposure to NO2 were associated with a reduction in microbial alpha diversity, while the effects of green space exposure were not evident. Acute and chronic (prenatal or postnatal) exposure to NO2 resulted in increased abundance of Haemophilus, Akkermansia, Alistipes, Eggerthella, and Tyzerella populations, while increasing green space exposure associated with increased Negativicoccus, Senegalimassilia and Anaerococcus and decreased Tyzzerella and Lachnoclostridium populations.

DISCUSSION

We observed a decrease in the diversity of the gut microbiota and signs of alteration in its composition among infants exposed to higher levels of NO2. Increasing green space exposure was also associated with changes in gut microbial composition. Further research is needed to confirm these findings.

Exposure to greenspaces sourced soils improves mice gut microbiota

Greenspaces are important components of our living environment and have been linked to various human health. However, the mechanisms underlying the linkages remain unclear. Enriching microbiota has emerged as a novel mechanism, but the corresponding evidence is still limited. We collected soil samples from forest land, grassland, and barren land in Zunyi City, southwestern China and prepared soil solutions. A total of 40 BALB/c mice were evenly divided into normal control group, model control group, forest soil group, grassland soil group, and barren land soil group. After establishing the pseudo germ-free mouse model, different soil solutions were administered through gavage, lasting for seven weeks. Fecal samples were collected and a 16S rRNA high-throughput sequencing analysis was performed. Then, alpha- and beta-diversity were calculated and employed to estimate the effects of soil exposures on mice gut microbial diversity and composition. Further, Linear Discriminant Analysis Effect Size (LEfSe) analysis was carried out to evaluate the effects of soil exposures on gut microbiota specific genera abundances and functional pathways. Compared to mice exposed to barren land soils, those exposed to soils sourced from forest land showed an increase of 0.43 and 70.63 units in the Shannon index and the Observed ASVs, respectively. In addition, exposure to soils sourced from forest land and grassland resulted in healthier changes (i.e., more short-chain fatty acids (SCFAs)-producing bacteria) in gut microbiota than those from barren land. Furthermore, mice exposed to forest soil and grassland soil showed enrichment in 5 and 3 pathways (e.g., butanoate metabolism) compared to those exposed to barren land soil, respectively. In conclusion, exposure to various greenspaces soils may modify the gut microbial communities of mice, potentially fostering a more beneficial microbiota profile. Further better-designed studies are needed to validate the current findings and to explore the effects of greenspace related gut microbiota on human health.

Physical activity promotes brain development through serotonin during early childhood

Early childhood serves as a critical period for neural development and skill acquisition when children are extremely susceptible to the external environment and experience. As a crucial experiential stimulus, physical activity is believed to produce a series of positive effects on brain development, such as cognitive function, social-emotional abilities, and psychological well-being. The World Health Organization recommends that children engage in sufficient daily physical activity, which has already been strongly advocated in the practice of preschool education. However, the mechanisms by which physical activity promotes brain development are still unclear. The role of neurotransmitters, especially serotonin, in promoting brain development through physical activity has received increasing attention. Physical activity has been shown to stimulate the secretion of serotonin by increasing the bioavailability of free tryptophan and enriching the diversity of gut microbiota. Due to its important role in modulating neuronal proliferation, differentiation, synaptic morphogenesis, and synaptic transmission, serotonin can regulate children's explicit cognitive and social interaction behavior in the early stages of life. Therefore, we hypothesized that serotonin emerges as a pivotal transmitter that mediates the relationship between physical activity and brain development during early childhood. Further systematic reviews and meta-analyses are needed to specifically explore whether the type, intensity, dosage, duration, and degree of voluntariness of PA may affect the role of serotonin in the relationship between physical activity and brain function. This review not only helps us understand the impact of exercise on development but also provides a solid theoretical basis for increasing physical activity during early childhood.

Unlocking the mind-gut connection: Impact of human microbiome on cognition

This perspective explores the current understanding of the gut microbiota's impact on cognitive function in apparently healthy humans and in individuals with metabolic disease. We discuss how alterations in gut microbiota can influence cognitive processes, focusing not only on bacterial composition but also on often overlooked components of the gut microbiota, such as bacteriophages and eukaryotes, as well as microbial functionality. We examine the mechanisms through which gut microbes might communicate with the central nervous system, highlighting the complexity of these interactions. We provide a comprehensive overview of the emerging field of microbiota-gut-brain interactions and its significance for cognitive health. Additionally, we summarize novel therapeutic strategies designed to promote cognitive resilience and reduce the risk of cognitive disorders, focusing on interventions that target the gut microbiota. An in-depth understanding of the microbiome-brain axis is imperative for developing innovative treatments aimed at improving cognitive health.

Mechanisms of Change in Nature-Based Pediatric Occupational Therapy: The Ecology of Change in Outdoor Therapy Model

The purpose of this qualitative constructivist grounded theory study was to develop a model to explain potential mechanisms of change in the nature-based pediatric occupational therapy process, based on analysis of the perspectives of occupational therapy practitioners currently engaging in nature-based practice with children. Using 27 photos and interview data from 22 participants the Ecology of Change in Outdoor Therapy (ECO-Therapy) Model was developed. The model suggests mechanisms of change in nature-based pediatric occupational therapy may involve six iterative phases: Longing for Freedom, Embarking on Adventure, Dancing with Nature, Claiming Self-Agency, Braving Real-Life Challenges, and Growing Adaptive Capacity. The practitioner and child experiencing these phases throughout the nature-based occupational therapy process may lead to improved participation and performance in the child's daily life.

Healthy childhood development through outdoor risky play: Navigating the balance with injury prevention

Free play is essential for children's development and for their physical, mental, and social health. Opportunities to engage in outdoor free play-and risky play in particular-have declined significantly in recent years, in part because safety measures have sought to prevent all play-related injuries rather than focusing on serious and fatal injuries. Risky play is defined by thrilling and exciting forms of free play that involve uncertainty of outcome and a possibility of physical injury. Proponents of risky play differentiate "risk" from "hazard" and seek to reframe perceived risk as an opportunity for situational evaluation and personal development. This statement weighs the burden of play-related injuries alongside the evidence in favour of risky play, including its benefits, risks, and nuances, which can vary depending on a child's developmental stage, ability, and social and medical context. Approaches are offered to promote open, constructive discussions with families and organizations. Paediatricians are encouraged to think of outdoor risky play as one way to help prevent and manage common health problems such as obesity, anxiety, and behavioural issues.

Le développement sain de l'enfant par le jeu risqué extérieur : un équilibre à trouver avec la prévention des blessures

Le jeu libre est essentiel pour le développement de l'enfant, de même que pour sa santé physique, mentale et sociale. Les occasions de se livrer au jeu libre extérieur, et au jeu risqué en particulier, ont considérablement diminué ces dernières années, en partie parce que les mesures de sécurité ont visé à prévenir toutes les blessures liées aux jeux plutôt que seulement les blessures graves et fatales. Le jeu risqué désigne des formes passionnantes et stimulantes de jeu libre dont l'issue est incertaine et qui comportent une possibilité de blessure physique. Les promoteurs du jeu risqué distinguent le « risque » du « danger » et aspirent à recadrer la perception du risque pour qu'il devienne une occasion d'évaluer une situation et de favoriser le développement personnel. Dans le présent document de principes, les auteures soupèsent le fardeau des blessures liées au jeu par rapport aux données probantes en appui au jeu risqué, notamment les avantages, les risques et les nuances, qui peuvent varier en fonction de l'étape de développement de l'enfant, de ses aptitudes et du contexte social et médical. Elles proposent des approches pour promouvoir des échanges ouverts et constructifs avec les familles et les organisations. Les pédiatres sont invités à percevoir le jeu risqué extérieur comme un moyen de contribuer à prévenir et à gérer des problèmes de santé courants tels que l'obésité, l'anxiété et les problèmes de comportement.

Effectiveness of Psychobiotic Bifidobacterium breve BB05 in Managing Psychosomatic Diarrhea in College Students by Regulating Gut Microbiota: A Randomized, Double-Blind, Placebo-Controlled Trial

Diarrhea of college students (DCS) is a prevalent issue among college students, affecting their daily lives and academic performance. This study aims to explore the potential effect of Bifidobacterium breve BB05 supplements on the DCS. Initially, fifty healthy and fifty diarrheal students were recruited in the observational experiment and allocated into control and diarrhea groups, respectively. Subsequently, one hundred diarrheal students were newly recruited in the intervention experiment and randomly allocated into placebo and probiotic groups, both treated for 2 weeks. Questionnaires (BSS, HAMA-14, and HDRS-17) were performed to assess the students' diarrheal states and mental health at baseline and post-treatment. Fecal samples underwent 16S rRNA sequencing and Enzyme-Linked Immunosorbent Assay to evaluate gut microbiota and fecal metabolite alternations. Results indicated that B. breve BB05 supplementation significantly enriched (p < 0.05) the reduced gut microbial diversity caused by diarrhea. Diarrhea resulted in notable alterations in gut microbiota composition, as exhibited by elevated Collinsella and Streptococcus, alongside substantially decreased Bifidobacterium, Bacteroides, and Prevotella, while B. breve BB05 supplementation partially restored the compromised gut microbiota at both the phylum and genus levels, particularly by increasing Bifidobacterium and Roseburia (p < 0.05). Importantly, questionnaire results suggested that B. breve BB05 administration achieved superior efficacy in relieving diarrhea symptoms and the associated anxiety and depression in college students. An increased fecal concentration of 5-hydroxytryptamine (5-HT) was also observed in the probiotic group, while Acetylcholine (ACH), Epinephrine (EPI), and Noradrenaline/Norepinephrine (NANE) reduced, revealing the potential of B. breve BB05 in alleviating anxiety and depression via modulating the microbiota-gut-brain axis. Furthermore, correlation analysis suggested that the altered microbiota and fecal neurotransmitters were closely associated with the mental symptoms. These results endorse B. breve BB05 intervention as a promising and innovative approach to alleviate both diarrhea and mental health conditions among college students.

Effect of gut microbiome on serotonin metabolism: a personalized treatment approach

Several factors including diet, exercise, and medications influence the makeup of the resilient but adaptable gut microbiome. Bacteria in the gut have a significant role in the homeostasis of the neurotransmitter serotonin, also known as 5-hydroxytryptamine, involved in mood and behavior. The goal of the current work is to review the effect of the gut microbiome on serotonin metabolism, and how it can potentially contribute to the development of a personalized treatment approach for depression and anxiety. Bacterial strains provide innovative therapeutic targets that can be used for disorders, such as depression, that involve dysregulation of serotonin. Advances in bacterial genomic sequencing have increased the accessibility and affordability of microbiome testing, which unlocks a new targeted pathway to modulate serotonin metabolism by targeting the gut-brain axis. Microbiome testing can facilitate the recommendation of strain-specific probiotic supplements based on patient-specific microbial profiles. Several studies have shown that supplementation with probiotics containing specific species of bacteria, such as Bifidobacterium and Lactobacillus, can improve symptoms of depression. Further research is needed to improve the process and interpretation of microbiome testing and how to successfully incorporate testing results into guiding clinical decision-making. This targeted approach centered around the gut-brain axis can provide a novel way to personalize therapy for mental health disorders.

Influence of Compost Amendments on Soil and Human Gastrointestinal Bacterial Communities during a Single Gardening Season

To measure associations between gardening with different compost amendments and the human gut microbiota composition, gardeners (n = 25) were provided with one of three types of compost: chicken manure (CM), dairy manure and plant material (DMP), or plant-based (P). Stool samples were collected before gardening (T1), after compost amendment (T2), and at peak garden harvest (T3). Compost and soil samples were collected. DNA was extracted, 16S rRNA libraries were established, and libraries were sequenced by Illumina MiSeq. Sequences were processed using mothur, and data were analyzed in R software version 4.2.2. Fast expectation-maximization microbial source tracking analysis was used to determine stool bacteria sources. At T2/T3, the gut microbiotas of P participants had the lowest Shannon alpha diversity, which was also the trend at T1. In stool from T2, Ruminococcus 1 were less abundant in the microbiotas of those using P compost as compared to those using CM or DMP. At T2, Prevotella 9 had the highest abundance in the microbiotas of those using CM compost. In participants who used CM compost to amend their gardening plots, a larger proportion of the human stool bacteria were sourced from CM compared to soil. Soil exposure through gardening was associated with a small but detectable change in the gardeners' gut microbiota composition. These results suggest that human interactions with soil through gardening could potentially impact health through alterations to the gut microbiota.

Urban indoor gardening enhances immune regulation and diversifies skin microbiota - A placebo-controlled double-blinded intervention study

According to the hygiene and biodiversity hypotheses, frequent exposure to environmental microbiota, especially through soil contact, diversifies commensal microbiota, enhances immune modulation, and ultimately lowers the risk of immune-mediated diseases. Here we test the underlying assumption of the hygiene and biodiversity hypotheses by instructing volunteers to grow edible plants indoors during the winter season when natural exposure to environmental microbiota is low. The one-month randomized, placebo-controlled double-blind trial consisted of two treatments: participants received either microbially diverse growing medium or visually similar but microbially poor growing medium. Skin microbiota and a panel of seven immune markers were analyzed in the beginning of the trial and after one month. The diversity of five bacterial phyla (Bacteroidetes, Planctomycetes, Proteobacteria, Cyanobacteria, and Verrucomicrobia) and one class (Bacteroidia) increased on the skin of participants in the intervention group while no changes were observed in the placebo group. The number of nodes and edges in the co-occurrence networks of the skin bacteria increased on average three times more in the intervention group than in the placebo group. The plasma levels of the immunomodulatory cytokine interleukin 10 (IL-10) increased in the intervention group when compared with the placebo group. A similar trend was observed in the interleukin 17A (IL-17A) levels and in the IL-10:IL-17A ratios. Participants in both groups reported high satisfaction and adherence to the trial. The current study provides evidence in support of the core assumption of the hygiene and biodiversity hypotheses of immune-mediated diseases. Indoor urban gardening offers a meaningful and convenient approach for increasing year-round exposure to environmental microbiota, paving the way for other prophylactic practices that might help prevent immune-mediated diseases.

Greenspace and human microbiota: A systematic review

BACKGROUND

Potential effect of greenspace exposure on human microbiota have been explored by a number of observational and interventional studies, but the results remained mixed. We comprehensively synthesized these studies by performing a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

METHODS

Comprehensive literature searches in three international databases (PubMed, Embase, and Web of Science) and three Chinese databases (China National Knowledge Infrastructure, Wanfang, and China Biology Medicine disc) were conducted from inception to November 1, 2023. Observational and interventional studies that evaluated associations between greenspace exposure and human microbiota at different anatomical sites were included. Studies were assessed using the National Toxicology Program's office of Health Assessment and Translation risk of bias tool and certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation framework. Two authors independently performed study selection, data extraction, and risk of bias assessment, and evidence grading. Study results were synthesized descriptively.

RESULTS

Twenty studies, including 11 observational studies and 9 interventional studies, were finally included into the systematic review. The microbiota of the included studies was from gut (n = 13), skin (n = 10), oral cavity (n = 5), nasal cavity (n = 5) and eyes (n = 1). The majority of studies reported the associations of greenspace exposure with increased diversity (e.g., richness and Shannon index) and/or altered overall composition of human gut (n = 12) and skin microbiota (n = 8), with increases in the relative abundance of probiotics (e.g., Ruminococcaceae) and decreases in the relative abundance of pathogens (e.g., Streptococcus and Escherichia/Shigella). Due to limited number of studies, evidence concerning greenspace and oral, nasal, and ocular microbiota were still inconclusive.

CONCLUSION

The current evidence suggests that greenspace exposure may diversify gut and skin microbiota and alter their composition to healthier profiles. These findings would be helpful in uncovering the potential mechanisms underlying greenspace and human health and in promoting a healthier profile of human microbiota.

Antibiotic-induced gut dysbiosis elicits gut-brain axis relevant multi-omic signatures and behavioral and neuroendocrine changes in a nonhuman primate model

Emerging evidence indicates that antibiotic-induced dysbiosis can play an etiological role in the pathogenesis of neuropsychiatric disorders. However, most of this evidence comes from rodent models. The objective of this study was to evaluate if antibiotic-induced gut dysbiosis can elicit changes in gut metabolites and behavior indicative of gut-brain axis disruption in common marmosets (Callithrix jacchus) - a nonhuman primate model often used to study sociability and stress. We were able to successfully induce dysbiosis in marmosets using a custom antibiotic cocktail (vancomycin, enrofloxacin and neomycin) administered orally for 28 days. This gut dysbiosis altered gut metabolite profiles, behavior, and stress reactivity. Increase in gut Fusobacterium spp. post-antibiotic administration was a novel dysbiotic response and has not been observed in any rodent or human studies to date. There were significant changes in concentrations of several gut metabolites which are either neurotransmitters (e.g., GABA and serotonin) or have been found to be moderators of gut-brain axis communication in rodent models (e.g., short-chain fatty acids and bile acids). There was an increase in affiliative behavior and sociability in antibiotic-administered marmosets, which might be a coping mechanism in response to gut dysbiosis-induced stress. Increase in urinary cortisol levels after multiple stressors provides more definitive proof that this model of dysbiosis may cause disrupted communication between gut and brain in common marmosets. This study is a first attempt to establish common marmosets as a novel model to study the impact of severe gut dysbiosis on gut-brain axis cross-talk and behavior.

Psychological Stress and Gut Microbiota Composition: A Systematic Review of Human Studies

INTRODUCTION

The associations between psychological stress and gut microbiota composition are not fully understood. This study investigated associations between psychological stress and gut microbiota composition and examined the potential modifying effects of age, sex, and ethnicity on such associations.

METHODS

A systematic literature search was conducted using PubMed, Web of Science, PsycINFO, and Embase databases for studies published until November 2021 which examined associations between psychological stress and gut microbiota composition.

RESULTS

During the search process, 10,790 studies were identified, and after screening, 13 met the eligibility criteria and were included. The median sample size was 70, and the median age of participants was 28.0 years. Most of the included studies did not report associations between measures of alpha- and beta diversity of the gut microbiota composition and psychological stress. A few studies reported that the Shannon index, Chao 1, Simpson index, and weighted UniFrac were negatively associated with psychological stress. Significant reductions in several taxa at the phyla-, family-, and genus-levels were observed in participants with higher psychological stress. At the phylum level, the abundance of Proteobacteria and Verrucomicrobia were negatively associated with psychological stress. At the family-level, no more than two studies reported associations of the same microbiota with psychological stress. At the genus level, the following results were found in more than two studies; psychological stress was negatively associated with the abundance of Lachnospira, Lachnospiraceae, Phascolarctobacterium, Sutterella, and Veillonella, and positively associated with the abundance of Methanobrevibacter, Rhodococcus, and Roseburia. However, it was not possible to determine the influence of age, sex, or ethnicity due to the limited studies included.

CONCLUSION

Our findings provide evidence that psychological stress is associated with changes in the abundance of the gut microbiota. Larger sample longitudinal studies are needed to determine the causal relationship between psychological stress and the gut microbiota.

The role of connection with nature in empirical studies with physiological measurements: a systematic literature review

It is well described that exposure to nature reduces physiological stress, and connectedness to nature can have a moderating effect. However, few studies have so far examined the construction of the connection with nature in relation to physiological processes. In this systematic review, we collected studies that used a physiological measure and included a scale to measure connectedness to nature. Our aim was to assess the role of nature relatedness at the level of physiological processes and to summarize the results published so far. Our review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A literature search was conducted in 3 different databases (PubMed, ScienceDirect and Google Scholar). As keywords, we used all the different questionnaires that measure connectedness to nature, combined with terms related to physiological measures. After final screening, 28 articles met the inclusion criteria for the review. The studies were very diverse in terms of purpose, intervention and methods, so narrative synthesis was conducted without measures of effect. We found evidence for a mediating effect of nature connectedness on the associations between nature exposure and cognitive function, brain activity, blood pressure, cortisol level and mental health. Studies investigating nature relatedness as state-like characteristics have shown that exposure to nature increases the level of connection to nature. Eye-tracking studies have confirmed that this measurement method can be used to investigate nature relatedness at a physiological level, which could be a useful complement to self-report questionnaires in future studies.

Abundance and prevalence of ESBL coding genes in patients undergoing first line eradication therapy for Helicobacter pylori

The spread of extended-spectrum beta-lactamases (ESBLs) in nosocomial and community-acquired enterobacteria is an important challenge for clinicians due to the limited therapeutic options for infections that are caused by these organisms. Here, we developed a panel of ESBL coding genes, evaluated the abundance and prevalence of ESBL encoding genes in patients undergoing H. pylori eradication therapy, and summarized the effects of eradication therapy on functional profiles of the gut microbiome. To assess the repertoire of known beta lactamase (BL) genes, they were divided into clusters according to their evolutionary relation. Primers were designed for amplification of cluster marker regions, and the efficiency of this amplification panel was assessed in 120 fecal samples acquired from 60 patients undergoing H. pylori eradication therapy. In addition, fecal samples from an additional 30 patients were used to validate the detection efficiency of the developed ESBL panel. The presence for majority of targeted clusters was confirmed by NGS of amplification products. Metagenomic sequencing revealed that the abundance of ESBL genes within the pool of microorganisms was very low. The global relative abundances of the ESBL-coding gene clusters did not differ significantly among treatment states. However, at the level of each cluster, classical ESBL producers such as Klebsiella sp. for blaOXY (p = 0.0076), Acinetobacter sp. for blaADC (p = 0.02297) and others, differed significantly with a tendency to decrease compared to the pre- and post-eradication states. Only 13 clusters were common across all three datasets, suggesting a patient-specific distribution profile of ESBL-coding genes. The number of AMR genes detected in the post-eradication state was higher than that in the pre-eradication state, which could be attributed, at least in part, to the therapy. This study demonstrated that the ESBL screening panel was effective in targeting ESBL-coding gene clusters from bacterial DNA and that minor differences exist in the abundance and prevalence of ESBL-coding gene levels before and after eradication therapy.

Association between Residential Greenness and Human Microbiota: Evidence from Multiple Countries

BACKGROUND

Greenness, referring to a measurement of the density of vegetated land (e.g., gardens, parks, grasslands), has been linked with many human health outcomes. However, the evidence on greenness exposure and human microbiota remains limited, inconclusive, drawn from specific regions, and based on only modest sample size.

OBJECTIVES

We aimed to study the association between greenness exposure and human microbial diversity and composition in a large sample across 34 countries and regions.

METHODS

We explored associations between residential greenness and human microbial alpha-diversity, composition, and genus abundance using data from 34 countries. Greenness exposure was assessed using the normalized difference vegetation index and the enhanced vegetation index mean values in the month before sampling. We used linear regression models to estimate the association between greenness and microbial alpha-diversity and tested the effect modification of age, sex, climate zone, and pet ownership of participants. Differences in microbial composition were tested by permutational multivariate analysis of variance based on Bray-Curtis distance and differential taxa were detected using the DESeq2 R package between two greenness exposure groups split by median values of greenness.

RESULTS

We found that higher greenness was significantly associated with greater richness levels in the palm and gut microbiota but decreased evenness in the gut microbiota. Pet ownership and climate zone modified some associations between greenness and alpha-diversity. Palm and gut microbial composition at the genus level also varied by greenness. Higher abundances of the genera Lactobacillus and Bifidobacterium, and lower abundances of the genera Anaerotruncus and Streptococcus, were observed in people with higher greenness levels.

DISCUSSION

These findings suggest that residential greenness was associated with microbial richness and composition in the human skin and gut samples, collected across different geographic contexts. Future studies may validate the observed associations and determine whether they correspond to improvements in human health. https://doi.org/10.1289/EHP12186.

Soil microbiome influences human health in the context of climate change

Soil microbiomes continue to evolve and shape the human microbiota according to external anthropogenic and climate change effects. Ancient microbes are being exposed as a result of glacier melting, soil erosion and poor agricultural practices. Soil microbes subtly regulate greenhouse gas emissions and undergo profound alterations due to poor soil maintenance. This review highlights how the soil microbiome influences human digestion processes, mineral and vitamin production, mental health and mood stimulation. Although much about microbial functions remains unknown, increasing evidence suggests that beneficial soil microbes are vital for enhancing human tolerance to diseases and pathogens. Further research is essential to delineate the specific role of the soil microbiome in promoting human health, especially in light of the increasing anthropogenic pressures and changing climatic conditions.

Mechanism and implications of pro-nature physical activity in antagonizing psychological stress: the key role of microbial-gut-brain axis

Appropriate physical activities and a biodiversity-rich environment are conducive to the relief of psychological stress, and pro-nature physical activities are a combination of the two, which has good application potential in antagonizing psychological stress, but the intervention mechanism is still unclear. The microbiota-gut-brain axis is cyclically associated with psychological stress, and psychological stress can affect the microbiota through the gut-brain pathway, and conversely, the microbiota can also affect the psychological stress-induced symptoms. It is suggested that the microbe-gut-brain axis may provide a new perspective and target for the treatment of psychological stress-related diseases. Pro-nature physical activity can improve the number of Firmicutes, short-chain fatty acids, Akkermansia bacteria, and the gut-brain barrier and further affect the HPA axis, BDNF, and serotonin pathways of gut-brain two-way communication, thereby maintaining the body's homeostasis and reducing antagonistic psychological stress. According to the comprehensive influence of physical activities on the microbiota-gut-brain axis, a "green + exercise prescription hypothesis" in line with the holistic medical concept is revealed, which is expected to be effective in the prevention, alleviation, and treatment of irritable bowel syndrome and neurodegenerative diseases. It provides new means for treating psychological stress-related diseases such as mental disorders and mood disorders. In addition, it enlightens the construction of green infrastructure that is conducive to the diversified contact of microorganisms in outdoor physical activities venues and induces healthy interaction between the human body and the microbial population in the natural ecology. However, the current research is still in its early stages, and the intervention effect and mechanism of pro-nature physical activities need further demonstration in the future.

What is Nature-Based Medicine and What Does It Do?

One's personal health and well-being can improve with activity in natural environments or decline without it. Many chronic illnesses to which personal nature deficiency contributes-including anxiety, depression, attention deficit, diabetes, hypertension, myopia, and obesity-have been exacerbated with the pandemic. That those illnesses may be preventable, treatable, and even reversible with an added nature-based approach may seem novel, but it is not. Though the field of nature-based medicine is just emerging in the U.S., it has been taught and practiced in Asia and the EU for decades. As the prescriptive, evidence-based use of natural settings and nature-based interventions, it aims to prevent and treat disease and improve well-being. Nature-based medicine blends particular activity in nature with the science of medicine to attempt to empower self-care safely, effectively, and happily. Its vision is to be readily available to all, regardless of proximity to blue (water-related) or green (land-related) space. The common sense of nature-based medicine belies its scientific evidence base, which is growing but not well-known, so it may seem unfamiliar to prescribe nature to patients. It will take education, training and practice to help patients access nature-based medicine and to help clinicians prescribe it.

A systematic review on the impact of gastrointestinal microbiota composition and function on cognition in healthy infants and children

Evidence from animal models or children with neurodevelopmental disorders has implicated the gut microbiome (GM) in neurocognitive development. However, even subclinical impairement of cognition can have negative consequences, as cognition serves as the foundation for skills necessary to succeed in school, vocation and socially. The present study aims to identify gut microbiome characteristics or changes in gut microbiome characteristics that consistently associate with cognitive outcomes in healthy, neurotypical infants and children. Of the 1,520 articles identified in the search, 23 were included in qualitative synthesis after applying exclusion criteria. Most studies were cross-sectional and focused on behavior or motor and language skills. Bifidobacterium, Bacteroides, Clostridia, Prevotella, and Roseburia were related to these aspects of cognition across several studies. While these results support the role of GM in cognitive development, higher quality studies focused on more complex cognition are needed to understand the extent to which the GM contributes to cognitive development.

The Gut Microbiome and Residential Surrounding Greenness: a Systematic Review of Epidemiological Evidence

PURPOSE OF REVIEW

A healthy indigenous intestinal microbiome is essential for human health. Well-established gut microbiome determinants only explain 16% of the inter-individual variation in gut microbiome composition. Recent studies have focused on green space as a potential determinant of the intestinal microbiome. We systematically summarize all evidence concerning the association between green space and intestinal bacterial diversity, evenness, and richness indices, specific bacterial taxa, and potential underlying mechanisms.

RECENT FINDINGS

Seven epidemiological studies were included in this review. The majority of the included studies (n = 4) reported a positive association between green space and intestinal bacterial diversity, evenness, and richness, while two reported the opposite. There was little overlap between the publications regarding the association between green space and the relative abundance of specific bacterial taxa. Only a decrease in the relative abundance of Bacteroidetes, Bacteroides, and Anaerostipes and an increase in Lachnospiraceae and Ruminococcaceae were reported in multiple studies, predominantly suggesting that green space is positively associated with the intestinal microbiome composition, and subsequently with human health. Lastly, the only examined mechanism was a reduction in perceived psychosocial stress. Mechanisms indicated in blue and white represent tested or hypothesized mechanisms, respectively. The graphical abstract was created with illustrations from BioRender, Noun Project, and Pngtree.

Air Pollution, Built Environment, and Early Cardiovascular Disease

As the world's population becomes increasingly urbanized, there is growing concern about the impact of urban environments on cardiovascular health. Urban residents are exposed to a variety of adverse environmental exposures throughout their lives, including air pollution, built environment, and lack of green space, which may contribute to the development of early cardiovascular disease and related risk factors. While epidemiological studies have examined the role of a few environmental factors with early cardiovascular disease, the relationship with the broader environment remains poorly defined. In this article, we provide a brief overview of studies that have examined the impact of the environment including the built physical environment, discuss current challenges in the field, and suggest potential directions for future research. Additionally, we highlight the clinical implications of these findings and propose multilevel interventions to promote cardiovascular health among children and young adults.

COVID-19: Reducing the risk via diet and lifestyle

This review shows that relatively simple changes to diet and lifestyle can significantly, and rapidly, reduce the risks associated with coronavirus disease 2019 (COVID-19) in terms of infection risk, severity of disease, and even disease-related mortality. A wide range of interventions including regular exercise, adequate sleep, plant-based diets, maintenance of healthy weight, dietary supplementation, and time in nature have each been shown to have beneficial effects for supporting more positive health outcomes with COVID-19, in addition to promoting better overall health. This paper brings together literature from these areas and presents the argument that non-pharmaceutical approaches should not be overlooked in our response to COVID-19. It is noted that, in several cases, interventions discussed result in risk reductions equivalent to, or even greater than, those associated with currently available vaccines. Where the balance of evidence suggests benefits, and the risk is minimal to none, it is suggested that communicating the power of individual actions to the public becomes morally imperative. Further, many lives could be saved, and many harms from the vaccine mandates avoided, if we were willing to embrace this lifestyle-centred approach in our efforts to deal with COVID-19.

Exiting the Anthropocene: Achieving personal and planetary health in the 21st century

Planetary health provides a perspective of ecological interdependence that connects the health and vitality of individuals, communities, and Earth's natural systems. It includes the social, political, and economic ecosystems that influence both individuals and whole societies. In an era of interconnected grand challenges threatening health of all systems at all scales, planetary health provides a framework for cross-sectoral collaboration and unified systems approaches to solutions. The field of allergy is at the forefront of these efforts. Allergic conditions are a sentinel measure of environmental impact on human health in early life-illuminating how ecological changes affect immune development and predispose to a wider range of inflammatory noncommunicable diseases (NCDs). This shows how adverse macroscale ecology in the Anthropocene penetrates to the molecular level of personal and microscale ecology, including the microbial systems at the foundations of all ecosystems. It provides the basis for more integrated efforts to address widespread environmental degradation and adverse effects of maladaptive urbanization, food systems, lifestyle behaviors, and socioeconomic disadvantage. Nature-based solutions and efforts to improve nature-relatedness are crucial for restoring symbiosis, balance, and mutualism in every sense, recognizing that both personal lifestyle choices and collective structural actions are needed in tandem. Ultimately, meaningful ecological approaches will depend on placing greater emphasis on psychological and cultural dimensions such as mindfulness, values, and moral wisdom to ensure a sustainable and resilient future.

The gut microbiome: an overview of current trends and risks for paediatric populations

PURPOSE OF REVIEW

Gut health is an increasingly popular topic of discussion among scientists and the general population alike. As interest surrounding the gut microbiome grows, the accessibility to misinformation and unfounded gut health trends to youth is likely to emerge as a public health concern. The purpose of this review is to provide paediatricians with current information about the gut microbiome, as well as explanations and possible risks of the multitude of gut health trends that adolescents may be exposed to.

RECENT FINDINGS

The gut microbiome is implicated in overall health by playing roles in digestion, immunity and mental health. Novel microbiome-related therapies, such as faecal microbiota transplants, and the gut-brain link show the therapeutic potential of the gut microbiome. However, unproven dietary fads and trends on social media are rampant as well, such as ginger juice shots. In addition, paediatric supplements meant to target gut health are unregulated, yet are highly marketed. Improperly applying these trends and diets may result in risks of malnutrition and body image issues for impressionable children.

SUMMARY

Increased familiarity regarding the types of gut health trends and diets among young people will allow paediatricians to more effectively advise their patients about potential risks and good gut health practices. Paediatricians and caregivers serve as role models and educators with regard to children's perceptions and management of their gut and overall health.

Assessing the relationship between physical activity and the gut microbiome in a large, population-based sample of Wisconsin adults

The gut microbiome is an important factor in human health and disease. While preliminary studies have found some evidence that physical activity is associated with gut microbiome richness, diversity, and composition, this relationship is not fully understood and has not been previously characterized in a large, population-based cohort. In this study, we estimated the association between several measures of physical activity and the gut microbiota in a cohort of 720 Wisconsin residents. Our sample had a mean age of 55 years (range: 18, 94), was 42% male, and 83% of participants self-identified as White. Gut microbial composition was assessed using gene sequencing of the V3-V4 region of 16S rRNA extracted from stool. We found that an increase of one standard deviation in weekly minutes spent in active transportation was associated with an increase in alpha diversity, particularly in Chao1's richness (7.57, 95% CI: 2.55, 12.59) and Shannon's diversity (0.04, 95% CI: 0.0008, 0.09). We identified interactions in the association between Inverse Simpson's diversity and physical activity, wherein active transportation for individuals living in a rural environment was associated with additional increases in diversity (4.69, 95% CI: 1.64, 7.73). We also conducted several permutational ANOVAs (PERMANOVA) and negative binomial regression analyses to estimate the relationship between physical activity and microbiome composition. We found that being physically active and increased physical activity time were associated with increased abundance of bacteria in the family Erysipelotrichaceae. Active transportation was associated with increased abundance of bacteria in the genus Phascolarctobacterium, and decreased abundance of Clostridium. Minutes in active transportation was associated with a decreased abundance of the family Clostridiaceae.

The Development and Acceptability of a Wilderness Programme to Support the Health and Well-Being of Adolescent and Young Adult Cancer Survivors: The WAYA Programme

Detailed descriptions of theory, structure, and activities with causal links to specified outcomes of wilderness programs are lacking. Addressing this gap, the present qualitative study gives a thorough description of the development of the Wilderness programme for Adolescent and Young Adult (AYA) cancer survivors (WAYA). WAYA is adapted to the individual needs of AYA cancer survivors. It was conceived around Næss's ecosophy and the Positive Health Model, and refined based on findings from a scoping review and patient/public involvement. Programme aims were to increase physical activity, self-confidence, personal growth, joy, safety within nature, meaningful relationships, and self-efficacy. The programme was an eight-day expedition followed three months later by a four-day base-camp. Activities included hiking, backpacking, kayaking, rock climbing, mindfulness and bushcrafting. Evaluation of the programme through focus group and individual interviews with 15 facilitators and 17 participants demonstrated that a diverse group of participants, challenging activities, and mindfulness-based practices were found to positively influence group bonding and the learning process. Furthermore, including an expedition and base-camp component was found to be beneficial in supporting the development of participants' own personal outdoor practices. In conclusion, this study demonstrated that the WAYA programme is safe and well accepted by AYA cancer survivors.

A Placebo-controlled double-blinded test of the biodiversity hypothesis of immune-mediated diseases: Environmental microbial diversity elicits changes in cytokines and increase in T regulatory cells in young children

BACKGROUND

According to the biodiversity hypothesis of immune-mediated diseases, lack of microbiological diversity in the everyday living environment is a core reason for dysregulation of immune tolerance and - eventually - the epidemic of immune-mediated diseases in western urban populations. Despite years of intense research, the hypothesis was never tested in a double-blinded and placebo-controlled intervention trial.

OBJECTIVE

We aimed to perform the first placebo-controlled double-blinded test that investigates the effect of biodiversity on immune tolerance.

METHODS

In the intervention group, children aged 3-5 years were exposed to playground sand enriched with microbially diverse soil, or in the placebo group, visually similar, but microbially poor sand colored with peat (13 participants per treatment group). Children played twice a day for 20 min in the sandbox for 14 days. Sand, skin and gut bacterial, and blood samples were taken at baseline and after 14 days. Bacterial changes were followed for 28 days. Sand, skin and gut metagenome was determined by high throughput sequencing of bacterial 16 S rRNA gene. Cytokines were measured from plasma and the frequency of blood regulatory T cells was defined as a percentage of total CD3 +CD4 + T cells.

RESULTS

Bacterial richness (P < 0.001) and diversity (P < 0.05) were higher in the intervention than placebo sand. Skin bacterial community, including Gammaproteobacteria, shifted only in the intervention treatment to resemble the bacterial community in the enriched sand (P < 0.01). Mean change in plasma interleukin-10 (IL-10) concentration and IL-10 to IL-17A ratio supported immunoregulation in the intervention treatment compared to the placebo treatment (P = 0.02). IL-10 levels (P = 0.001) and IL-10 to IL-17A ratio (P = 0.02) were associated with Gammaproteobacterial community on the skin. The change in T_reg frequencies was associated with the relative abundance of skin Thermoactinomycetaceae 1 (P = 0.002) and unclassified Alphaproteobacteria (P < 0.001). After 28 days, skin bacterial community still differed in the intervention treatment compared to baseline (P < 0.02).

CONCLUSIONS

This is the first double-blinded placebo-controlled study to show that daily exposure to microbial biodiversity is associated with immune modulation in humans. The findings support the biodiversity hypothesis of immune-mediated diseases. We conclude that environmental microbiota may contribute to child health, and that adding microbiological diversity to everyday living environment may support immunoregulation.

Interplay between natural environment, human microbiota and immune system: A scoping review of interventions and future perspectives towards allergy prevention

BACKGROUND

Urbanization and biodiversity loss are linked to chronic disorders, in particular allergic diseases. The aim of this scoping review was to provide a synopsis of intervention studies specifically examining the influence of exposure to natural environments on human microbiota as well as immunological markers as suggested interlink between natural environment and the development of allergic diseases.

METHODS

We searched PubMed (MEDLINE®) and all references cited in the included studies following the PRISMA statement guidelines. No restrictions regarding age and sex of study participants, language or publication date were made. The protocol was registered at OSF REGISTRIES (https://osf.io/musgr).

RESULTS

After screening, eight intervention studies were included. The interventions reported were mainly of pilot character and various, ranging from nature-related educational programs, biodiversity interventions in day-cares to short-term contact with soil- and sand-preparations. Most of the studied interventions appeared to increase human microbiota richness and diversity in specific taxa groups in the short-time. Immunological markers were assessed in only two studies. In these, their associations with human microbiota richness were pre-dominantly reported.

CONCLUSION

There is some evidence that the so-called biodiversity interventions have the potential to diversify human microbiota, at least over a short period. Adequately powered randomized controlled trials with long term follow-up are required to examine sustainable effects on microbiota and immune system.

The 4E approach to the human microbiome: Nested interactions between the gut-brain/body system within natural and built environments

The complexity of the human mind and its interaction with the environment is one of the main epistemological debates throughout history. Recent ideas, framed as the 4E perspective to cognition, highlight that human experience depends causally on both cerebral and extracranial processes, but also is embedded in a particular sociomaterial context and is a product of historical accumulation of trajectory changes throughout life. Accordingly, the human microbiome is one of the most intriguing actors modulating brain function and physiology. Here, we present the 4E approach to the Human Microbiome for understanding mental processes from a broader perspective, encompassing one's body physiology and environment throughout their lifespan, interconnected by microbiome community structure and dynamics. We review evidence supporting the approach theoretically and motivates the study of the global set of microbial ecosystem networks encountered by a person across their lifetime (from skin to gut to natural and built environments). We furthermore trace future empirical implementation of the approach. We finally discuss novel research opportunities and clinical interventions aimed toward developing low-cost/high-benefit integrative and personalized bio-psycho-socio-environmental treatments for mental health and including the brain-gut-microbiome axis.

Roseburia, a decreased bacterial taxon in the gut microbiota of patients suffering from anorexia nervosa

Anorexia nervosa (AN) is a severe eating disorder which can lead to malnutrition and life threatening complications with high mortality rates. We designed our analysis to identify gut microbial taxa differentially abundant between AN and HC across different 16S rRNA gene datasets. We identified a reduced abundance, diversity and richness of Roseburia genus in the microbiota of patients with AN. Cares leading to partial recovery of patients with AN during hospitalization did not restore Roseburia to the levels of HC. AN dietary habit, either purgative or restrictive, did not affect Roseburia abundance. Roseburia genus and related species abundance were correlated with different health host metabolic markers. Roseburia species are key functional taxa in the human gut microbiome. Low gut Roseburia levels have been linked with other human pathologies. Our study highlights Roseburia species as a major decreased component in the gut of patients with AN.

A Systematic Review of Arts-Based Interventions Delivered to Children and Young People in Nature or Outdoor Spaces: Impact on Nature Connectedness, Health and Wellbeing

Background

The time that children and young people spend in nature and outdoor spaces has decreased significantly over the past 30 years. This was exacerbated with a further 60% decline post-COVID-19. Research demonstrating that natural environments have a positive impact on health and wellbeing has led to prescription of nature-based health interventions and green prescribing, although evidence for its use is predominantly limited to adults. Growing evidence also shows the impact of arts on all aspects of health and wellbeing. However, what has received scant attention in literature is the interconnection between the two: arts and nature.

Aims

This review synthesizes the literature surrounding the interconnectedness between arts and nature, and their impact on the health and wellbeing of children and young people.

Methods

Eight major electronic databases were systematically searched, while hand-searching included 20 journals, six books, and contact with experts. The review was conducted using the Cochrane handbook for systematic reviews, PRISMA guidelines and TIDieR template. All stages were conducted independently by two researchers and the protocol was published on PROSPERO (Registration no.: CRD42021286574).

Results

Although 9,314 records were identified, only 11 records were included as most studies focused either on arts or nature, but not both. Studies were conducted in United Kingdom, United States, Ireland, Australia, and Hong Kong, in a range of spaces such as forests, woodlands, beaches, parks, fields, gardens, and school playgrounds. The review encompasses data from 602 participants in total.

Discussion

Arts-in-nature offered an inclusive medium to engage all children and young people, especially those who might otherwise remain disinterested about environmental issues and disengaged with educational programs. Further, arts-in-nature provided stimuli to increase nature connectivity, understand environmental issues and explore ways to prevent environmental disasters. This led to higher environmental awareness and pro-environmental behaviors, and potential decrease in eco-anxiety.

Conclusion

Although the quality of qualitative studies was high, the quality of quantitative studies was low or unclear, thus quantitative evidence is still at its infancy. Implications for research, policy, and practice are discussed, such as methods and activities to strengthen future interventions. Scaling-up existing interventions may lead to wider recognition and inclusion of arts-in-nature in future health guidelines, including green prescribing.

Bi-Directionality of the Microbiota-Gut-Brain Axis in Patients With Functional Dyspepsia: Relevance of Psychotherapy and Probiotics

Functional dyspepsia is one of the most commonly diagnosed disorders of the gut-brain interaction worldwide. The precise pathogenesis of functional dyspepsia is complex and remains incompletely understood. Therefore, advances in the understanding of functional dyspepsia could change clinical practice. The aim of this review is to highlight the relevance of psychotherapy and probiotics in the context of the microbiota-gut-brain axis in the pathophysiology and especially in the treatment of functional dyspepsia. Therefore, studies which have been conducted to investigate the role of psychotherapy and probiotics in FD and the microbiota-gut-brain axis in the pathophysiology of functional dyspepsia were examined, and the outcomes of this research summarized. There might be a link between changes in the microbiome and functional dyspepsia. Even though, specific alterations in the microbiome that may be pathognomonic in functional dyspepsia remain unclear, the use of probiotics became a viable treatment option for patients with functional dyspepsia. Since mental illness also plays an important role in the pathophysiology of functional dyspepsia, psychotherapy is a useful treatment method, with additional study results indicating that psychotherapy may also shift the microbiome in a favorable direction. Moreover, other findings suggest that probiotics can be used not only to alleviate gastrointestinal symptoms in functional dyspepsia, but also to treat or even prevent mental disorders in these patients. In summary, in this review we highlight the bi-directionality of the microbiota-gut-brain axis in the pathophysiology of functional dyspepsia. Although there are multiple treatment approaches, the burden of disease in patients with functional dyspepsia is still enormous and a definitive therapy to cure this disease does not (yet) exist. Lastly, there is a lack of studies on the impact of dysbiosis, mental health and probiotics on pathophysiology and symptomatology in functional dyspepsia which should be investigated in future studies.

Cross-Sectional Analysis of the Microbiota of Human Gut and Its Direct Environment in a Household Cohort with High Background of Antibiotic Use

Comprehensive insight into the microbiota of the gut of humans and animals, as well as their living environment, in communities with a high background of antibiotic use and antibiotic resistance genes is scarce. Here, we used 16S rRNA gene sequencing to describe the (dis)similarities in the microbiota of feces from humans (n = 107), domestic animals (n = 36), water (n = 89), and processed food (n = 74) in a cohort with individual history of antibiotic use in northern Vietnam. A significantly lower microbial diversity was observed among individuals who used antibiotics in the past 4 months (n = 44) compared to those who did not (n = 63). Fecal microbiota of humans was more diverse than nonhuman samples and shared a small part of its amplicon sequence variants (ASVs) with feces from animals (7.4% (3.2–9.9)), water (2.2% (1.2–2.8)), and food (3.1% (1.5–3.1)). Sharing of ASVs between humans and companion animals was not associated with the household. However, we did observe a correlation between an Enterobacteriaceae ASV and the presence of extended-spectrum beta-lactamase CTX-M-group-2 encoding genes in feces from humans and animals (p = 1.6 × 10⁻³ and p = 2.6 × 10⁻², respectively), hinting toward an exchange of antimicrobial-resistant strains between reservoirs.

Nature and Children's Health: A Systematic Review

CONTEXT

Daily outdoor play is encouraged by the American Academy of Pediatrics. Existing evidence is unclear on the independent effect of nature exposures on child health.

OBJECTIVE

We systematically evaluated evidence regarding the relationship between nature contact and children's health.

DATA SOURCES

The database search was conducted by using PubMed, Cumulative Index to Nursing and Allied Health Literature, PsychInfo, ERIC, Scopus, and Web of Science in February 2021.

STUDY SELECTION

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In all searches, the first element included nature terms; the second included child health outcome terms.

DATA EXTRACTION

Of the 10 940 studies identified, 296 were included. Study quality and risk of bias were assessed.

RESULTS

The strongest evidence for type of nature exposure was residential green space studies (n = 147, 50%). The strongest evidence for the beneficial health effects of nature was for physical activity (n = 108, 32%) and cognitive, behavioral, or mental health (n = 85, 25%). Physical activity was objectively measured in 55% of studies, and 41% of the cognitive, behavioral, or mental health studies were experimental in design.

LIMITATIONS

Types of nature exposures and health outcomes and behaviors were heterogenous. Risk of selection bias was moderate to high for all studies. Most studies were cross-sectional (n = 204, 69%), limiting our ability to assess causality.

CONCLUSIONS

Current literature supports a positive relationship between nature contact and children's health, especially for physical activity and mental health, both public health priorities. The evidence supports pediatricians in advocating for equitable nature contact for children in places where they live, play, and learn.