Can furry pets reduce infant obesity?

Pet owners often wax lyrical about how their pets enrich their lives, but did you know pets can affect us at a more microscopic level? Research published today in Microbiome by Anita Kozyrskyj and colleagues show that exposure to household pets leads to changes in infant gut microbiota that in turn could reduce infant obesity.

We are all full of harmless microbes that form our microbiota, but we are not born with these. Our microbiota develops over time and with exposure to the world around us. The gut microbiota of a newborn is not diverse, but by the age of one the gut microbiota begins to resemble that of  an adult. Despite gut colonization being relatively quick, the period just before and after birth is a critical time for gut microbiota development in infants.

It is already known that the make up of our microbiota can impact our current and future health, and this make up depends on our lifestyles and environment. It then stands to reason that an infant’s environment can affect its microbiota and consequently its health – possibly even impacting on later childhood and adult health. Furthermore, dysbiosis or an imbalance in the gut microbiome can lead us to develop more allergies. Dysbiosis is attributed to an overly hygienic environment, where reduced exposure to microbes contributes to the immune system becoming imbalanced.

dog-1023933_960_720Pet ownership – or rather exposure – in the first years of life has already been shown to reduce allergic sensitisation, so could exposure to furry household pets bring about other health benefits and how is this mediated?

Anita Kozyriskyj and colleagues report in the journal Microbiome that exposure to household pets pre and post birth enriched the abundance of two types of bacteria: Oscillospira and Ruminococcus species in 3-4 month old infants. The impact of pet exposure varied depending on the method of birth and, for the portion of infants who were exposed to pets during pregnancy alone, this was enough to increase the abundance of Oscillospira and Ruminococcus species.

Oscillospira is associated with leanness or lower body mass index in infants and adults.

What, you may ask, is the significance of the enrichment of these two types of bacteria in an infant’s gut? Oscillospira is associated with leanness or lower body mass index in infants and adults. This is through its positive interaction with Christenseella minuta which is a leanness-promoting bacterium. Ruminococcus’s role in infant health is poorly understood, but they have been linked to lower food sensitivity.

A word of warning though before everyone rushes off to the pet shop: microbiota studies are seldom clear cut, because the microbiota is such a complex, convoluted system. Further investigations to better elucidate the mechanisms through which pets impact our microbiota is definitely needed here. There are also many unanswered questions including:

  • Do different pets produce different impacts?
  • How long does the effect of this childhood exposure last?
  • Would enrichment of certain microbial species in the gut lead to negative, unpredicted consequences?
  • Could there be external factors that negate or boost the connection between pet ownership and childhood obesity?

Pets can of course enrich our lives, but we have also seen zoonotic diseases emerge from humans living in close contact with animals, so there needs to be a balance and we should proceed with caution…. and people certainly should not see pets as a dieting aid.

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