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Two decades of research have made it clear that children who grow up with dogs have lower rates of asthma than those who do not. Many researchers attribute this finding to the hygiene hypothesis — the idea that exposure to a little dirt early in life can ward off allergic diseases that can appear later. Without firm data to show a link between owning a dog and improved immune health, however, the idea remained alluring, but unproven.
Perhaps mums who own dogs are healthier or more likely to breastfeed, says Anita Kozyrskyj, a paediatric epidemiologist at the University of Alberta in Edmonton, Canada. “It could be the lifestyle.”
In 2013, Kozyrskyj set out to see if she could pinpoint what might be going on. Kozyrskyj's team evaluated the various microbes present in 24 faecal samples collected between 2008 and 2009 from 4-month-old infants enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) cohort study. Of the 24 babies, 15 lived in houses with at least 1 dog or cat1.
The researchers discovered that infants living with pets had a higher diversity of microbes in their guts (as measured in their faeces) than infants without pets. A generation ago, Kozyrskyj's findings would have been cause for alarm. Microbes — synonymous at the time with germs — were thought to be best kept at bay. A family history of allergies may even have prompted physicians to advise expectant parents to give up the family pet.
But now, says Kozyrskyj, it's known that the immune system develops alongside the gut microbiome — the genetic material of the community of microorganisms that live in the gut. That means that if infants grow up with limited exposure to microbes, such as those present in dog fur or those tracked into the house on muddy paws, the child's immune system may deem those particles worthy of attack.
Perhaps mums who own dogs are healthier or more likely to breastfeed, says Anita Kozyrskyj, a paediatric epidemiologist at the University of Alberta in Edmonton, Canada. “It could be the lifestyle.”
In 2013, Kozyrskyj set out to see if she could pinpoint what might be going on. Kozyrskyj's team evaluated the various microbes present in 24 faecal samples collected between 2008 and 2009 from 4-month-old infants enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) cohort study. Of the 24 babies, 15 lived in houses with at least 1 dog or cat1.
The researchers discovered that infants living with pets had a higher diversity of microbes in their guts (as measured in their faeces) than infants without pets. A generation ago, Kozyrskyj's findings would have been cause for alarm. Microbes — synonymous at the time with germs — were thought to be best kept at bay. A family history of allergies may even have prompted physicians to advise expectant parents to give up the family pet.
But now, says Kozyrskyj, it's known that the immune system develops alongside the gut microbiome — the genetic material of the community of microorganisms that live in the gut. That means that if infants grow up with limited exposure to microbes, such as those present in dog fur or those tracked into the house on muddy paws, the child's immune system may deem those particles worthy of attack.
Microbiome: Puppy power - Nature
Once anathema, it now seems that a 'dirty' environment can enrich a baby's microbiome and lessen her or his likelihood of developing everything from obesity to asthma. Again, it seems that we can rely on man's best friend to help us out.
www.nature.com
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