The First Swiss National Nutrition Survey in Children and Adolescents, menuCH-Kids: Study Design, Participants, and Data Quality.

Objectives
menuCH-Kids was launched to generate the first Swiss nationwide children's dietary data, assess food contaminant exposure, and inform nutrition policies. This paper describes the methods, data quality, and participants characteristics.
Methods
In 2023-2024, a cross-sectional population-based survey in six Swiss centres collected dietary data via two non-consecutive 24-hour recalls/records and a Food Propensity Questionnaire; lifestyle, health, eating behaviours and sociodemographic information via online questionnaires; anthropometrics, urine, and voluntary blood samples by trained professionals with standardized procedures in 6-17-year-olds. Area-based socioeconomic position (Swiss-SEP) was linked to home addresses. Statistical weights corrected for unequal selection probabilities and non-response. Factors associated with participation were explored using logistic regressions.
Results
1,852 participants attended the visit (participation rate = 11.9%). Data quality was high (<6% missing values, 15.1% dietary under-reporters, and 98% of biosamples processed on time). Non-participants were older, male, non-Swiss, from lower socioeconomic neighbourhoods, and smaller household. Adding socioeconomic position improved participation prediction models.
Conclusion
menuCH-Kids provides high-quality dietary and health data on Swiss youth. Low participation highlights the need for a weighting strategy including socioeconomic position to compensate biases.