Relative Validity of a Semi-Quantitative Food Frequency Questionnaire to Estimate Dietary Intake According to the NOVA Classification in Mexican Children and Adolescents

Background Ultra-processed foods (UPFs) are associated with poor diet quality and chronic diseases. UPFs fall into 1 of the following 4 groups classified according to the extent and purpose of processing: group 1 is unprocessed or minimally processed foods (MPFs); group 2 is processed culinary ingredients; group 3 is processed foods; and group 4 is UPFs. Objective The aim of this study was to evaluate the relative validity of a semi-quantitative food frequency questionnaire (SFFQ) compared with two 24-hour dietary recalls (24DRs) 'to estimate dietary intake per NOVA food group in Mexican children and adolescents. Design This study is a secondary analysis of dietary data from a subsample of children and adolescents who participated in the 2012 Mexican National Health and Nutrition Survey. Participants/setting The study participants were 217 children (aged 5 through 11 years) and 165 adolescents (aged 12 through 19 years) with complete information for the SFFQ and two 24DRs. Main outcome measures Daily averages of energy intake and percent of energy intake for each NOVA category were calculated using the SFFQ and two 24DRs. Statistical analysis To assess relative validity, the SFFQ was compared with two 24DRs to estimate dietary intake per NOVA food group. Mean differences, Spearman correlations, intraclass correlations coefficients (ICCs), and Bland-Altman plots for continuous variables and weighted kappa for ordinal variables were calculated. Results For percentage of energy intake, ICCs in children and adolescents were moderate for MPFs (ICC = 0.47 and ICC = 0.56, respectively) and UPFs (ICC = 0.53 and ICC = 0.57, respectively). Bland-Altman plots indicated reasonably consistent agreement for UPFs and MPFs groups in children and adolescents. Classification by quintiles was acceptable in all groups. Conclusions Data from this study indicated reasonable relative validity of the SFFQ to rank the percentage of energy intake from MPFs and UPFs in Mexican children and adolescents.