Methodological aspects of the assessment of dietary intake in the Brazilian National Survey on Child Nutrition (ENANI-2019): a population-based household survey.

This manuscript aims to describe the methodological, operational, and quality control aspects of the assessment of dietary intake in children under five years of age participating in the Brazilian National Survey on Child Nutrition (ENANI-2019), a household survey in a probability sample of Brazilian households. Two instruments were developed to assess child feeding practices - a structured, current status-type questionnaire and a 24-hour dietary recall (24HR), both installed in a mobile data collection device used by previously trained interviewers. A Photographic Manual for Quantification of Children's Dietary Intake was specifically developed for and used in the survey as a support aid to identify and quantify foods reported in the 24HR. During the fieldwork, continuous quality control of the records was performed. Data errors or incomplete data in the system were corrected, and the fieldwork team was systematically contacted and informed on their performance, with reiterated orientation on data collection. All children in the sample were evaluated with the two instruments, but data were obtained from the structured questionnaire on all children in the sample (n = 14,558) and 24HR on 14,541 children. ENANI-2019 developed innovative methods and materials based on the Brazilian and international literature to address knowledge gaps on under-five children's dietary intake. Unprecedented results will be produced, which will allow updating food and nutrition guidelines for children under five years of age in Brazil.