Wonder Bacteria From Pets Prevent Allergies, Obesity

Corroborating a widely held belief, a new study claims immunity improvement in toddlers living with fur buddies. Allergies apart, the research also shows a pet can lower risk of childhood obesity.

The study from University of Alberta built on data from Canadian Healthy Infant Longitudinal Development study shows that a pet at home can lower allergies risk and obesity under various birth scenarios. However, exposure to animals must happen during what researchers termed a 'critical window' to accrue benefits.

"To investigate the impact of pre- and postnatal pet exposure on infant gut microbiota following various birth scenarios, this study employed a large subsample of 746 infants from the Canadian Healthy Infant Longitudinal Development Study (CHILD) cohort, whose mothers were enrolled during pregnancy between 2009 and 2012," the study authors wrote in the publication that appeared in the journal Microbiome.
"Participating mothers were asked to report on household pet ownership at recruitment during the second or third trimester and three months postpartum."
Subsequently, gut bacteria from infant feces was sampled to determine presence of Ruminococcus and Oscillospira, bacteria known to mitigate risk of childhood obesity and allergies.

"The abundance of these two bacteria were increased twofold when there was a pet in the house," said Anita Kozyrskyj, a pediatric epidemiologist at the university and the paper's corresponding author.

More importantly, the findings shed light on the transfer of immunity from pets to children; it can happen directly through dirt and bacteria in a pet's fur, and indirectly in the womb from mother to baby. That apart, researchers were able to show enhanced immunity against allergies with a pet at home even in babies delivered through c-section and when mothers did not breastfeed, two conditions known to negatively affect immunity.

"The impact of pet ownership varies under different birth scenarios; however, in common, exposure to pets increased the abundance of two bacteria, Ruminococcus and Oscillospira, which have been negatively associated with childhood atopy and obesity."
Immunity to allergies and obesity can only be gained if pet exposure occurs at a certain phase in the gut's microbiome development, the authors note.

"There's definitely a critical window of time when gut immunity and microbes co-develop, and when disruptions to the process result in changes to gut immunity," Kozyrsky said. Researchers found that exposure to a pet up to three months after birth increases the abundance of beneficial bacteria in the gut, and in turn, boosts immunity against allergies while lowering risk of obesity.

Early exposure to dirt and bacteria is linked with lower risk of allergic conditions including rhinitis and asthma. The body's immune system, blamed for allergic reactions, can modulate response during the development phase to later cope efficiently in presence of allergens during adulthood. On the flip-side to keeping a cat or dog at home, are pet triggered allergies that can show much later in life and sometimes even in pet lovers.

The American Academy of Allergy Asthma & Immunology claims that millions of Americans are allergic to pets which dwell in nearly two-thirds of US homes.
"The proteins found in a pet's dander, skin flakes, saliva and urine can cause an allergic reaction or aggravate asthma symptoms in some people. Also, pet hair or fur can collect pollen, mold spores and other outdoor allergens."
The timing of pet exposure thus most likely is the moot point in the debate over keeping a pet and allergies. That notwithstanding, the study's authors foresee pharma giants making dogs available in a 'pill' for pregnant mothers who wish to keep allergies at bay.

"It's not far-fetched that the pharmaceutical industry will try to create a supplement of these microbiomes, much like was done with probiotics," Kozyrskyj said.

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