As kids we heard “Go play in the dirt, it’s good for you”, and now as adults we put mud on our faces, participate in ‘mud runs’, and some even eat dirt for a health kick. Meanwhile, immunologists and medical researchers have also been steadily building knowledge of the beneficial connections between the diversity of microbial communities living in and on our bodies, and our ability to build and maintain a healthy immune system.
However, until now, links between soil and immune fitness have been untested at the population-level. A new study, led by Craig Liddicoat of The University of Adelaide, has, for the first time, examined the public health benefits of exposure to soil across Australia.
“We suspected that soils with high microbial diversity would have the greatest benefit for immune fitness and wanted to test this across the population,” says Craig. “So what we have done is compare the locations of such soils, and human exposure to them, with hospital admission rates for infectious and parasitic diseases across regional Australia.”
“Our results show that in socioeconomically-deprived areas with high biodiversity soils, rates of infectious and parasitic disease are significantly lower than areas with low diversity soils. We also found that the health risk due to lower socioeconomic status is significantly lower in areas with high diversity soils”
So, not only does exposure to soils with high microbial diversity—as indicated by their cation exchange capacity (CEC)—give you a health advantage, but it also lowers the general health risks that are normally associated with low socioeconomic conditions.
Soil-associated microbes are part of the ‘aerobiology’ that connects people with their surrounding environment (image courtesy of the Government of South Australia Department for Environment and Water)
To identify the areas of Australia with high CEC soils, or the healthy soil hotspots, Craig and his colleagues used the data and infrastructure provided by TERN and our fellow NCRIS project, Bioplatforms Australia.
The team used Bioplatform Australia’s Biomes of Australian Soil Environments (BASE)—a collaborative project involving over 80 partners including TERN—to analyse nation-wide data on soil microbial communities and key soil parameters such as CEC.
“The existing coverage of soil microbial data alone wasn’t sufficient to compare directly with population health. However, the BASE data gave us the confidence to use soil CEC as a surrogate for microbial diversity across regional Australia. This step justified our use of nation-wide soil CEC mapping to estimate relative exposures to soil microbial diversity in our analysis.”
Critical to the study, the soil CEC mapping came straight from TERN’s Soil and Landscape Grid of Australia. Following further refinement and analyses, these soil data were then compared against a suite of health and environmental data to produce the final health and socioeconomic risk analyses.
“Our results not only suggest health benefits and reduced disease risk from exposure to high CEC soils, they also demonstrate that knowledge of the spatial distribution of soil CEC can improve the prediction of infectious and parasitic disease risk in unseen test areas,” says Craig.
“Without access to the nationwide, open access data provided by TERN and Bioplatforms Australia, such a population-level analysis and this significant finding simply wouldn’t have been possible.”
We’ll leave you with a tip from Craig for your weekend… “It's time to get our hands dirty and help build more biodiversity into our soils. Think of it like going to the gym for your immune system. After all, a little dirt never hurt!”
Map of regional Australian local government areas (LGAs) used in the study
Published in TERN newsletter May 2018