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How does the environment impact the occurrence of food sensitization?

Published online: March 18, 2019

The presence of IgE antibodies against food is known as food sensitization (FS). FS is a prerequisite for development of food allergy. The prevalence of FS varies remarkably across Europe, and is reported to be on the rise. Environmental exposures are thought to influence these geographical and temporal variations in FS. Studies evaluating environmental risk factors for FS are key to helping us understand differences in prevalence and time trends between and within populations.    

In a study recently published in The Journal of Allergy and Clinical Immunology: In Practice, Lyons et al. investigated how environmental exposures are associated with FS in childhood and adulthood. Evaluated environmental exposures primarily comprised early-life exposures. These exposures included, amongst others, siblingship size, day care attendance, bedroom sharing, pet ownership, growing up in a farm environment, (parental) smoking and infant diet (determinants related to breastfeeding, infant formula and introduction of solid foods). Data were collected from 2196 school-age children and 2185 adults who participated in the EuroPrevall population surveys across Europe.

Analyses divulged that having a pet dog before the age of two years was the only statistically significant predictive early-life exposure. In accordance with previous studies, dog ownership was found to be strongly associated with a decreased risk of FS in childhood. Other postulated environmental and infant dietary risk factors for food allergy appear to have a (more) limited impact, though having (older) siblings, day care attendance, bedroom sharing, growing up in a farm environment, breastfeeding for longer than six months, and early introduction of solid foods did show trends towards reduction in the likelihood of FS in either childhood or adulthood. Interestingly, early-life farm exposure, but also bedroom sharing in childhood, showed a stronger preventative tendency for sensitization to inhalant allergens than for sensitization to food allergens. These findings suggest that predictors for food and inhalant sensitization differ regarding their importance, despite shared pathophysiological mechanisms.

All in all, this study provides evidence in support of the protective effect of dog ownership in early childhood against the development of FS in later childhood, but presents much more modest associations between other postulated environmental risk factors, such as siblingship size, day care attendance, bedroom sharing, farm environment, and infant diet, and FS in childhood and adulthood.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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