Background: Diet-gut microbiota-disease hypothesis for atopic dermatitis (AD) has been studied in infancy, but its implications for preschool-aged children remain less understood. This study aims to investigate the relationships among dietary patterns, gut microbiota, and disease severity in Korean preschoolers. Methods: We evaluated 97 preschool children aged 3–6 years, including 46 with AD and 51 healthy controls (CON). Dietary intake was assessed using a Food Frequency Questionnaire (FFQ), and dietary patterns were analyzed through factor analysis of the FFQ. AD severity was assessed using EASI, SCORAD and CDLQI scores. Gut microbiota composition was characterized using 16S rRNA sequencing. Results: Through factor analysis of food group, Q1 (Traditional Korean Diet Pattern) and Q2 (Processed Food and Snack Pattern) were identified. AD-Q2 diet had lower vitamin C intake compared to those on the AD-Q1 diet (p=0.011). Dorea and Anaerostipes were more prevalent in the AD-Q2 group (LDA score: 3.4 and 3.9, respectively). The AD-Q2 group also reported significantly poor CDLQI and high nighttime itching compared to the AD-Q1 group (p=0.032 and 0.041, respectively). Insufficient intake of vitamin C was significantly associated with increased EASI and SCORAD (r = -0.52, p = 0.03; r = -0.41, p = 0.045, respectively), whereas the presence of Dorea and Anaerostipes also positively correlated with itching. Conclusions: In preschool children with AD, the Processed Food and Snack dietary pattern was associated with increased disease severity, potentially mediated by Dorea and Anaerostipes abundance and vitamin C deficiency, impacting the gut environment and inflammation pathways.

Background: It is necessary to evaluate the parental ability to achieve nutritional adequacy while avoiding allergens for children with food allergies (FA), yet this area is currently understudies. Our study aimed to develop and validate the Parental Self-Efficacy Scale for Dietary Management of Children with Food Allergies (PSED-FA). Methods: PSED-FA was developed through a literature review and semi-structured interviews, refined by a panel of five allergists and five dietitians, and validated using responses from caregivers of children with FA. The construction of the tool involved exploratory factor analysis (EFA), confirmatory factor analysis for model fit, and evaluation of internal consistency using Cronbach’s alpha. Convergent and divergent validity were assessed using the average variance extracted (AVE), maximum shared variance (MSV), and average shared variance (ASV). Results: Participants included nine focus interview groups, with 114 individuals in the validation group. Egg whites (55.2 %), tree nuts (35.2%), and peanuts (22.8%) were the most common allergens. The EFA identified three factors: preparing allergen-free meals, knowledge of nutrition management, and management of food restrictions. The goodness of fit of our model met all the criteria. The tool showed high internal consistency (overall Cronbach’s alpha: 0.902) and met the criteria for both convergent (AVE >0.5) and divergent validity (AVE >MSV and ASV). Conclusion: This study validated a reliable and effective tool for assessing parental self-efficacy in managing the dietary needs of children with FA. This tool can aid health professionals in evaluating parental confidence and identifying areas for improving dietary management in children with FA.