A complex interplay of genetic, environmental, and microbial factors drives the development of food allergies in children, according to a large-scale meta-analysis published today, , in JAMA Pediatrics. The study, involving nearly 2.8 million children from 40 countries, sheds light on the multifaceted nature of these increasingly common immune responses to food.
Approximately 5% of children will develop a food allergy by the age of six, the research indicates. While family history plays a role, the study emphasizes that genetics alone cannot fully explain the rising prevalence of food allergies, suggesting a “perfect storm” of interacting factors is at play. “Our study highlights that genetics alone cannot fully explain food allergy trends, pointing to interactions – or a ‘perfect storm’ – between genes, skin health, the microbiome, and environmental exposures,” explains Derek Chu, senior author of the study and assistant professor with McMaster University’s Departments of Medicine and Health Research Methods, Evidence, and Impact.
The researchers systematically examined over 340 potential risk factors, identifying several early-life conditions that significantly increase a child’s susceptibility. Notably, infants who experience eczema during their first year of life are three to four times more likely to develop a food allergy. Wheezing or nasal allergies also elevate the risk. This connection underscores the importance of skin barrier function in early immune development.
A family history of allergies – particularly in both parents – also increases a child’s likelihood of developing a food allergy. However, the study also pinpointed specific timing related to allergen introduction as a critical factor. Delaying the introduction of allergenic foods, such as peanuts, tree nuts, and eggs, beyond 12 months of age more than doubles the risk of developing an allergy to those foods.
This finding reinforces current recommendations for early allergen introduction in appropriate infants, a strategy designed to build tolerance rather than avoidance. The researchers found that babies who first tried peanuts after 12 months were more than twice as likely to develop a peanut allergy.
The study also highlighted the potential impact of early antibiotic exposure. Antibiotic use during the first month of life was associated with an increased risk of food allergy, although the risk appears to be somewhat diminished with later antibiotic use or maternal antibiotic use during pregnancy.
Interestingly, the research also identified factors not associated with an increased risk of food allergies. These include low birth weight, post-term birth, partial breastfeeding, maternal diet during pregnancy, and maternal stress during pregnancy. This helps refine the understanding of which infants are most vulnerable and where preventative efforts should be focused.
The findings are significant because they help identify which infants are most at risk and could benefit most from early prevention strategies. The study’s large scale – encompassing data from 190 previous investigations – provides a robust foundation for these conclusions. Researchers systematically reviewed cohort, case-control, and cross-sectional studies, including those that confirmed allergy diagnoses through oral food challenge testing, considered the gold standard for allergy confirmation.
The investigators classified major risk factors as those with larger effect sizes and risk differences, including early allergic disease, delayed allergen introduction, early-life antibiotic exposure, parental migration, and family history of allergy.
While this study represents a substantial advance in understanding food allergy development, the authors emphasize the need for further research. Future studies should strive to measure and adjust for the key factors identified in this meta-analysis, include more diverse populations, and utilize oral food challenge testing more frequently to ensure accurate diagnoses. This will allow for a more nuanced understanding of the complex interplay of factors contributing to food allergies and ultimately lead to more effective prevention and management strategies.
The research expands “our understanding of food allergies” and provides a framework for future investigations, according to Chu. The ultimate goal is to develop targeted interventions to reduce the burden of food allergies on children and families.
