Pet cats and dogs may help protect infants from food allergies, study suggests

A new study found young children exposed to cats or indoor dogs had a lower risk of all food allergies compared with babies in pet-free homes. (Paulo Sousa/EyeEm/Getty Images)

Children who live with cats or dogs during fetal development and early infancy may be less likely than other kids to develop food allergies, according to a new study.

The study, published Wednesday in the journal PLOS One, analyzed data from over 65,000 children from Japan. It found that children exposed to cats or indoor dogs had a 13 per cent to 16 per cent lower risk of all food allergies compared with babies in pet-free homes.

"Our findings suggest that exposure to dogs and cats might be beneficial against the development of certain food allergies, thereby alleviating concerns about pet keeping and reducing the burden of food allergies," the authors wrote.

The study found that children exposed to cats were less likely to develop egg, wheat and soybean allergies, while those exposed to dogs were less likely to have egg, milk and nut allergies.

Although there was no association between turtles and birds and food allergies, hamster exposure during fetal development was linked with nearly twice the risk of nut allergies. The authors speculate that nuts that hamsters consume may sensitize infants through physical contact or house dust.

The exact mechanism remains unclear, but experts say pet exposure may strengthen an infant's gut microbiome, either directly or indirectly though changes in the parent's or home microbiome.

"We know from a lot of studies that the microbiome -- which are the bacteria that live within us, thousands and millions of them inside everybody's gut -- affect our immune responses and our immune system, particularly whether we develop allergies or not," said Dr. Amal Assa'ad, director of the Food Allergy Program at Cincinnati Children's Hospital, who was not involved with the new research.

Dr. Jonathan Bernstein, president of the American Academy of Allergy, Asthma, and Immunology, says dirt and other materials secreted by pets could be a good thing.

"It is critical to have these exposures early on as the immune system is developing, as the gut is developing, because it does seem to be an important route for sensitization," said Bernstein, who was not involved with the study.

Previous research has had mixed results. Some have linked pet exposure to decreased risk of food allergy, but others have found no association.

"The data is all over the place," Assa'ad said.

Although the researchers on the new study accounted for several factors that could influence the participant's risk of food allergy -- including mother's age, history of allergic disease, smoking status and place of residence -- they say it's possible that other factors influenced the results.

Additionally, food allergy data was self-reported, which relies on accurate diagnosis from participants, the researchers say.

"There's a need to really confirm these types of studies," Bernstein said. "So I wouldn't necessarily change lifestyles based on this data, but I wouldn't certainly get rid of pets in the home."

Experts hope these results can help guide research into the drivers behind childhood food allergies and reassure pet owners.

"If you're thinking about having an animal and you're concerned because you have allergies ... there may be an added benefit to having an animal, not just in terms of what it does for families and people's general love of pets, but also, it could be potentially protective if there's an early life exposure," Bernstein said.