Dogs and natural areas could reduce a baby’s risk of allergies by improving the health of their guts, suggests a new study.
University of Alberta paediatrics Prof. Anita Kozyrskyj co-authored a study in Environment International July 9 on how exposing urban babies to nature affects the bacteria in their guts.
Gut microbes play an important role in food digestion and the production of various nutrients, and are thought to train an infant’s immune system to react appropriately to its environment, Kozyrskyj said.
There’s also growing evidence that these microbes influence the development of allergies, asthma, obesity and diabetes, with the current global fall in human microbe diversity linked to the rise of immune and inflammatory disorders. Researchers now suspect exposure to natural environments could prevent such problems by improving microbe populations in people.
Poop, dogs and guts
Kozyrskyj and her team wanted to see if exposure to natural areas could affect a baby’s gut microbes. They sampled faeces from 355 four-month-old babies from the Edmonton and St. Albert region (via diapers) and did a DNA analysis of them to find out types and quantities of bacteria in their guts. These babies were part of the ongoing national CHILD Cohort study, which is tracking some 3,500 Canadian children from birth to adolescence to find the root causes of allergies, asthma and chronic diseases.
The team cross-referenced each baby’s postal code with the City of Edmonton’s urban Primary Land and Vegetation Inventory map to determine how close each one was to a natural area, such as a ravine, forest or lake.
The team found babies who lived within 500 metres of a natural area were less likely to have higher diversity amongst their gut bacteria.
While high microbe diversity is associated with good health in adults, research shows you actually want less diversity in babies, explained Kathy McCoy, who studies gut microbes at the University of Calgary’s International Microbiome Centre and was not involved with this study. Babies need very specific, less diverse microbes in their guts to set up their immune systems, specifically the ones adapted to digest breast milk. Studies have found breast-fed babies have less diverse gut microbes than formula-fed ones and go on to have fewer health problems.
While the team found all babies close to natural areas had less diverse microbes than those far from them, they found statistically significant differences only amongst babies who were close to nature, not breast-fed, and had pets in the home.
“We think the dog is the conduit,” Kozyrskyj said.
While the study didn’t note what type of pet was in each house, parents with dogs would be more likely to take their kids and dogs outside into nature, Kozyrskyj said. Dogs could also track beneficial microbes into a home through their feet and fur.
McCoy said this study suggests taking your kid out into nature and owning a pet would probably improve the health of their gut, but not as much as breast-feeding them would.
Formula-fed babies have more diverse gut microbes than breast-fed ones because formula contains simpler sugars that more microbes can digest, Kozyrskyj said. That diversity could raise a baby’s risk of developing allergies and other problems. Parents who can’t breast-feed their kids should get a pet and get their kids outdoors to offset that risk.
Kozyrskyj said this was the first study of its kind to look at the link between a baby’s gut microbes and nature. Her team now hopes to track the formula-fed babies in this study to see if nature exposure actually does improve their health.
The study is available at bit.ly/2BX0Jz2.