Ultra-Processed Foods Consumption and Metabolic Syndrome in European Children, Adolescents, and Adults: Results from the I.Family Study

: Background/Objectives: Ultra-processed foods (UPFs) constitute a large proportion of the daily energy intake of Europeans, particularly among children and adolescents. High UPFs consumption is associated with poor dietary quality and adverse health outcomes. This study aimed to examine whether high UPFs consumption is associated with metabolic health in children, adolescents, and adults, using data from the I.Family study. Methods: This cross-sectional analysis (2013/2014) included 2285 participants: 147 children (6-9 years), 645 adolescents (10-19 years), and 1493 adults (≥20 years). For the children and adolescents, a metabolic syndrome (MetS) z-score was calculated, consisting of age- and sex-standardized z-scores of WC, HOMA index, HDL-C, TRG, systolic blood pressure (SBP), and diastolic blood pressure (DBP). For the adults, MetS was defined according to the criteria of the International Diabetes Federation Task Force and other societies. The participants completed at least one 24 h recall, from which their UPFs consumption was estimated using the NOVA classification. The consumption levels were divided into age- and sex-specific quintiles based on the relative energy contribution of these foods. Multivariable regression analyses were conducted to evaluate the associations between UPFs consumption and MetS or its components. Results: No statistically significant associations were found between UPFs consumption and MetS or its components in any age group. The effect sizes were negligible across the quintiles (η2 = 0.0065 in children, 0.015 in adolescents, and 0.0009 in adults). While the mean MetS score showed little variation, the prevalence of MetS scores above the 90th percentile increased in the highest UPFs quintile among the children. The diet quality decreased with increasing UPFs consumption. Conclusions: UPFs consumption was not associated with MetS or its components across the age groups. However, a decline in diet quality was observed with increasing UPFs intake, highlighting the importance of public health strategies to reduce UPFs consumption and improve dietary patterns, particularly among younger populations.