However, hamsters were associated with an increased risk of nut allergies. Other kinds of pets, such as turtles and birds, were not significantly associated with any food allergies. Certain allergies, including for fish, fruit, crustaceans, and buckwheat noodles, were not significantly associated with pet exposure.

Commentary

According to the Wall Street Journal, the study builds on previous research, including a recent study from South Africa that found exposure to farm animals could decrease a child's risk of food or other allergies.

The researchers also noted that the current study is unique due to its large sample size, variety of pets and foods included, and how it differentiated between prenatal and postnatal exposure.

According to the researchers, the "hygiene hypothesis" could explain why pet exposure may impact food allergies. The hypothesis suggests that contact with bacteria and other microbes, including from animals, may be crucial in building a robust, healthy immune system.

Having pets in a home may help inoculate children's GI tract and ultimately lead to an immune system that is less sensitive to certain allergens.

"Pet exposure may increase abundance of certain gut microbes as well as contribute to the diversity of gut bacteria, which is possibly associated with lower rates of allergic disease," said Hisao Okabe, the study's lead author from Fukushima Medical University.

Edwin Kim, chief of pediatric allergy-immunology at the University of North Carolina School of Medicine, noted that rates of food allergies are higher in the developed world, where disinfectants and other conveniences may limit exposure to microbes.

"Are we too clean, not challenging our immune systems the way they should be?" Kim asked. Although he praised the current study's large sample size, he also noted that participants were limited to Japan, so the findings may not be applicable to other countries.

Currently, CDC data shows that over 5% of children in the United States have food allergies, and these allergies can sometimes have serious, or even life-threatening consequences. To gather more data on children in the United States, NIH has sponsored a U.S. birth cohort study called Sunbeam. The study is examining early risk factors for allergies, including environmental exposure, and could help confirm as well as expand on the study from Japan. (Ulick, Wall Street Journal, 3/29; Okabe et al., PLOS ONE, 3/29)