Growing evidence suggests that exposure to food allergens begins far earlier than previously understood, with implications for how food allergies may develop in infancy. A recent study examining the home environments of infants aged 3-4 months, prior to the introduction of solid foods, found that multiple food allergens are already present in household dust.
Proteins from hen’s egg, cow’s milk and wheat were detected in every sample, while peanut allergens were present in nearly nine out of ten homes. Concentrations of these food allergens were frequently higher than those of common environmental allergens such as house dust mites, indicating that routine household activities, including food preparation and consumption, contribute directly to indoor allergen levels.
These findings support the “dual allergen exposure” hypothesis, which proposes that while early dietary introduction of allergenic foods can promote immune tolerance, exposure through the skin – particularly in infants with immature skin barriers – may increase the risk of sensitisation. Importantly, infants may encounter allergens via bedding and surfaces long before they consume them orally.
The study highlights the need to consider both dietary and environmental sources of exposure when developing allergy prevention strategies. It also points to the influence of household behaviours, with evidence that allergen levels can rise rapidly following food handling or consumption.
For full details, see the open access publication: Environmental food allergen levels in early infancy.
