D1.242 - Early-Life Dietary Diversity and the Risk of Atopic Dermatitis: A Nationwide Population-Based Cohort Study

Exposure to dietary antigens via the gut mucosa during infancy is essential for immune tolerance and may influence the subsequent development of allergic diseases. However, epidemiological evidence linking early dietary diversity to atopic dermatitis (AD) remains limited. We aimed to investigate whether dietary diversity before one year of age is associated with the subsequent risk of AD.

We conducted a nationwide population-based cohort study using customized data from the Korean National Health Insurance Service. Among 799,428 children born in Korea between 2009 and 2010, those who underwent the National Health Screening Program for Infants and Children at approximately 1 year of age were included. Dietary exposure was assessed using a parental questionnaire administered during the National Health Screening Program for Infants and Children, which evaluated the intake of six predefined complementary food groups. Participants were categorized according to the number of food groups consumed: 1–2, 3–4, and 5–6 food groups, with the 5–6 group serving as the reference. The date of questionnaire completion was defined as the index date. Children with atopic dermatitis diagnosed before the index date were excluded. Participants were followed from the index date until 2023, and incident atopic dermatitis was identified using insurance claims data. The risk of atopic dermatitis was assessed using Cox proportional hazards models.

A total of 267,935 children were included in the final analysis. The mean age at dietary assessment was 0.94 years (SD 0.27), and 50.7% were male. Of the participants, 20,362 (7.6%) were exposed to 1–2 food groups, 95,242 (35.5%) to 3–4 food groups, and 152,331 (56.8%) to 5–6 food groups. The incidence rates of AD per 10,000 person-years were 109.9 in the 5–6 food group, 122.7 in the 3–4 food group, and 120.6 in the 1–2 food group. Compared with children exposed to 5–6 food groups, the risk of AD was significantly higher in those exposed to 3–4 food groups (hazard ratio [HR] 1.11, 95% confidence interval [CI] 1.09–1.13) and 1–2 food groups (HR 1.08, 95% CI 1.04–1.12).

Lower dietary diversity before one year of age was associated with an increased risk of subsequent atopic dermatitis. These findings support the hypothesis that early exposure to a diverse range of complementary foods may play a protective role in the development of atopic dermatitis and provide population-based evidence relevant to infant feeding recommendations.