Food allergies often feel unpredictable, especially for parents trying to do everything “right.” A large new analysis suggests the risk is shaped less by any single choice and more by a mix of early-life factors that interact during infancy and early childhood.
The study, published in JAMA Pediatrics, reviewed data from nearly 2.8 million children across 190 studies worldwide. Researchers examined a wide range of influences on food allergy development, from genetics and early feeding practices to skin health, antibiotic exposure and environmental conditions.
Overall, about 5% of children developed a food allergy by age 6. The strongest and most consistent risk factors clustered early in life, particularly during infancy, when the immune system and gut microbiome are still developing.
One of the clearest signals involved eczema. Children who developed eczema in the first year of life were significantly more likely to go on to develop a food allergy, especially when eczema appeared early or was more severe. A family history of allergies also raised risk, particularly when both parents had allergic conditions.
Timing of food introduction mattered as well. Delaying the introduction of common allergenic foods, such as peanuts or eggs, was associated with a higher likelihood of food allergy later on. Infants who first tried peanuts after 12 months of age had more than double the risk of developing a peanut allergy compared with those introduced earlier.
The review also found that antibiotic use very early in life was linked to increased allergy risk. Antibiotics taken in the first month of life showed the strongest association, while use later in infancy or during pregnancy appeared to carry a smaller increase in risk. Researchers note that antibiotics can disrupt the developing gut microbiome, which plays an important role in immune training.
At the same time, the analysis helped clarify what didn’t appear to raise food allergy risk. Factors such as low birth weight, being born after the due date, partial breastfeeding and maternal stress during pregnancy were not consistently linked to higher allergy rates.
Rather than pointing to a single cause, the findings support the idea that food allergies emerge from overlapping biological and environmental influences. Skin barrier health, microbial exposure and early feeding patterns appear to interact with genetic susceptibility, shaping how the immune system responds to foods.
The authors emphasize that these results should be used to guide prevention strategies, not to assign blame. Many risk factors are outside parental control, and food allergy development cannot be traced back to one decision or exposure.
This research was supported by the Canadian Institutes of Health Research and the AAAAI/ACAAI Joint Task Force on Allergy Practice Parameters.