Children exposed to pet cats or indoor dogs during foetal development or early infancy tended to have fewer food allergies than other children, according to an analysis of more than 65 000 infants from Japan, published in PLOS ONE.
Across some high-income countries, more than one in 10 children are diagnosed with food allergies, and numbers continue to rise. Previous research has suggested a potential link between dog or farm animal exposure in pregnancy and early childhood and the reduction of food allergies.
This latest study, by Hisao Okabe from the Fukushima Regional Centre for the Japan Environment and Children’s Study, and colleagues, used data from nationwide, prospective birth cohort research to study 66 215 children, for whom data on exposure to various pets and food allergies were available.
About 22% were exposed to pets during the foetal period (most commonly indoor dogs and cats), among whom there was a significantly reduced incidence of food allergies, though there was no significant difference for children in households with outdoor dogs.
Youngsters exposed to indoor dogs were also significantly less likely to experience egg, milk, and nut allergies specifically, and those exposed to cats were significantly less likely to have egg, wheat and soybean allergies.
Perhaps surprisingly, children exposed to hamsters (0.9% of the total group studied) had significantly greater incidence of nut allergies.
The data used were self-reported (supplemented by medical record data gathered during the first trimester of pregnancy, at delivery, and at the one-month check-up), so the study relies on the accurate recall of participants.
Additionally, the researchers cannot determine if the link between pet exposure and food allergy incidence is causative. Still, they suggest that these results can help guide future research into the mechanisms behind childhood food allergies.
Study details
Associations between foetal or infancy pet exposure and food allergies: The Japan Environment and Children’s Study
Hisao Okabe, Koichi Hashimoto, Mika Yamada, Takashi Ono, Kazufumi Yaginuma, Yohei Kume, Mina Chishiki, Akiko Sato, Yuka Ogata, Karin Imaizumi, Tsuyoshi Murata, Hyo Kyozuka, Kosei Shinoki, Seiji Yasumura, Hidekazu Nishigori, Keiya Fujimori, Mitsuaki Hosoya.
Published in PLOS ONE on 29 March 2023
Abstract
The hygiene hypothesis suggests that pet exposure is effective in preventing allergic disease, and some studies have reported the beneficial effects of dog exposure during foetal development or early infancy on food allergy. However, the effects of exposure to pets other than dogs on the kinds of food allergies remains unaddressed. This study aimed to explore the effect of exposure to various species of pets on the risk of food allergies.
We obtained information on pet exposure and food allergy from the Japan Environment and Children’s Study, a nationwide, prospective birth cohort study that included 97 413 mothers and their children. We examined the associations between exposure to various species of pets during foetal development or early infancy and the incidence risk of food allergies. We conducted logistic regression analysis for each pet species, causative food, and timing of exposure. Exposure to dogs or cats during foetal development or early infancy was estimated to reduce the incidence risk of food allergies until the age of three years. Dog exposure was estimated to reduce the incidence risk of egg, milk, and nut allergies, and cat exposure was estimated to reduce the incidence risk of egg, wheat, and soybean allergies. However, hamster exposure was estimated to increase the incidence risk of nut allergy.
In conclusion, the association between pet exposure and food allergies might differ depending on the pet species and causative food. Continued dog and cat exposure from foetal development to infancy was estimated to reduce the incidence risk of food allergies. The findings of this study shall aid in the design of future studies.
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