A Frequency-Based Proxy Score for Ultra-Processed Food Consumption Among Adolescents: Associations with Lifestyle Factors and Tinnitus.

Background/Objectives: Ultra-processed food (UPF) consumption is increasingly recognized as part of broader adverse behavioral and health-related patterns in young people, yet evidence integrating dietary, sleep-related, behavioral, and health characteristics within the same adolescent population remains limited. The relationship between UPF-related dietary patterns and tinnitus is particularly understudied. This study examined factors associated with the highest category of a frequency-based proxy UPF score among adolescents in Belgrade, Serbia. Methods: A school-based cross-sectional study included 1285 students aged 15-19 years from 12 four-year secondary schools selected using a stratified multistage cluster probability sampling design. A frequency-based proxy UPF score was constructed from seven questionnaire-based food categories broadly consistent with UPF-related consumption patterns in the Serbian context. Participants were grouped into three categories using empirical tertile cut-points, and the highest category was modeled as the binary outcome in univariable and multivariable logistic regression analyses. Results: Lower academic achievement (aOR = 2.10; 95% CI: 1.38-3.21), alcohol consumption (aOR = 1.34; 95% CI: 1.04-1.74), and waking tired compared with waking rested (aOR = 1.58; 95% CI: 1.06-2.35) were associated with higher odds of being in the highest proxy-score category after adjustment for the measured covariates. Energy drink consumption frequency was also associated with the outcome after adjustment for the measured covariates (overall p < 0.001). Constant tinnitus showed one of the strongest adjusted associations (aOR = 2.55; 95% CI: 1.77-3.67). Conclusions: Adolescents in the highest category of the frequency-based proxy UPF score exhibited a broader pattern of academic, sleep-related, behavioral, and health characteristics, including a particularly strong association with constant tinnitus. These cross-sectional findings warrant longitudinal research to clarify temporal relationships and underlying determinants.