Mudpies vs sandcastles, which is best for kids?
Aussies in awe of outside play. And .... Happy Midsummer's Day!
Advancing urbanisation and fragmentation of habitats along with the increase of immunological non-communicable diseases in developed countries led to the formulation of the biodiversity hypothesis. It is based on the fact that nature is one of the richest sources of microbial input, and that reduced exposure to natural environments and biodiversity may adversely affect our microbiota and its immunomodulatory capacity. - L Andersen, et al.
Studies of preschoolers do show that children are twice as active and less sedentary when playing outdoors compared to indoors in child care settings. Spending time outdoors also strengthens their immune systems. They experience fewer illness-related absences from child care when they have daily opportunities to play outside.
In Scandinavia, kindergarden kids can attend “Forest Schools” where they play outside, all day, all seasons.
Today is the summer solstice here in the Northern Hemisphere, but winter solstice in the Land Down Under, Australia. They must have summer on their minds, though, gifting us with an analysis of the best sites where children can gain diverse microbial exposure, for improving their overall health.
H I G H L I G H T S
Childcare centre soils are more bacterially diverse than sandpits.
Soil bacterial communities are distinct between different soil substrates.
Plant species richness and habitat condition influence soil bacterial communities.
Soil areas in childcare centres may modulate child exposure to diverse bacteria.
Urban development has profoundly reduced human exposure to biodiverse environments, which is linked to a rise in human disease. The ‘biodiversity hypothesis’ proposes that contact with diverse microbial communities (microbiota) benefits human health, as exposure to microbial diversity promotes immune training and regulates immune function. Soils and sandpits in urban childcare centres may provide exposure to diverse microbiota that support immunoregulation at a critical developmental stage in a child’s life. However, the influence of outdoor substrate (i.e., sand vs. soil) and surrounding vegetation on these environmental microbiota in urban childcare centres remains poorly understood. Here, we used 16S rRNA amplicon sequencing to examine the variation in bacterial communities in sandpits and soils across 22 childcare centres in Adelaide, Australia, plus the impact of plant species richness and habitat condition on these bacterial communities. We show that sandpits had distinct bacterial communities and lower alpha diversity than soils. In addition, we found that plant species richness in the centres’ yards and habitat condition surrounding the centres influenced the bacterial communities in soils but not sandpits. These results demonstrate that the diversity and composition of childcare centre sandpit and soil bacterial communities are shaped by substrate type, and that the soils are also shaped by the vegetation within and surrounding the centres. Accordingly, there is potential to modulate the exposure of children to health-associated bacterial communities by managing substrates and vegetation in and around childcare centres. - NS Newman, et al.
So how is it that mucking around in mud, is good for you? My past newsletter addressed this question.
“A link to microbiomes may help explain many green space-human health associations. Controlled experimental evidence testing possible beneficial effects from passive exposure to natural biodiversity via airborne microbiota demonstrate that realistic exposures to dust from a high biodiversity soil can change mouse gut microbiota. A soil-derived anaerobic spore-forming butyrate-producer, Kineothrix alysoides, increased in the gut microbiomes of high biodiversity treatment mice, and correlated with reduced anxiety-like behavior in mice. Biodiverse soils may represent an important source of butyrate-producing bacteria capable of reseeding the mammalian gut microbiome, potentially improving gut and mental health.”
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Perhaps a good way for us all to diversify our soil exposure is …
by celebrating Midsummer’s Day the Swedish way:
REFERENCES
L Andersen, et al. Nature Exposure and Its Effects on Immune System Functioning: A Systematic Review. Int J Environ Res Public Health. 2021 Feb 3;18(4):1416. doi: 10.3390/ijerph18041416
PS Tandon, et al. A Comparison of Preschoolers' Physical Activity Indoors versus Outdoors at Child Care. Int J Environ Res Public Health. 2018 Nov 5;15(11):2463. doi: 10.3390/ijerph15112463.
NS Newman, et al. Childcare centre soil microbiomes are influenced by substrate type and surrounding vegetation condition. Science of the Total Environment 927 (2024) 172158 https://doi.org/10.1016/j.scitotenv.2024.172158
