Ultra-Processed Food Intake and Its Dietary Sources and Correlates Among Polish Young Adults: A Cross-Sectional Study

Background/Objectives: Individual-level data on ultra-processed food (UPF) intake among Polish young adults are limited. This study quantified absolute UPF intake and its weight-based dietary contribution, identified major dietary sources, and examined associations of the UPF weight ratio with sociodemographic and anthropometric factors. Methods: This cross-sectional study included 429 Polish adults aged 18-30 years recruited by convenience sampling through an online questionnaire in March-April 2026, using a non-probabilistic sampling procedure. Habitual dietary intake was assessed using an 82-item semi-quantitative food-frequency questionnaire; body height and weight were self-reported. Foods were classified according to NOVA, supported by a market analysis of 605 retail products. Absolute UPF intake (g/day) and the UPF weight ratio (% of total food and non-water beverage intake) were calculated. Group comparisons used non-parametric tests, and independent associations were examined using multiple linear regression. Results: Median UPF intake was 394.4 g/day, while the mean UPF weight ratio was 23.8 ± 14.67%. Men had significantly higher UPF intake and weight ratio than women (p < 0.001, p = 0.002). The largest contributors to total UPF intake were non-alcoholic beverages (22.7%), animal protein products (19.7%), ready-to-eat/convenience meals (9.2%), and sweets and snacks (7.0%). In multivariable analysis, higher age (B = -1.47) and higher education (B = -3.55) were independently associated with a lower UPF weight ratio, while male sex (B = 2.87) and higher BMI (B = 0.36) were associated with a higher ratio (model R² = 25.0%). Conclusions: UPF intake was substantial in this convenience sample. A higher UPF weight ratio was observed among younger participants, men, and those with lower educational attainment, while beverages were the leading dietary source. These findings may help identify priority groups and dietary sources for public health strategies.