Ultra-processed food (UPF) intake is high among adolescent populations worldwide. This study aimed to characterize the UPF intake and assess its contribution to the traditional diet of Costa Rican adolescents. Using cross-sectional data from 3-day food records obtained from 818 adolescents (13-18 years) from San José, Costa Rica, we calculated the daily % of total energy intake (TEI) from Nova-defined UPF, the Traditional Costa Rica Adolescents Diet Score (TCRAD; higher score reflecting higher traditional adherence), other nutrients, and fiber. The multivariable-adjusted mean UPF intakes were compared across participants' characteristics, mealtime, and days of the week, and assessed for association with TCRAD (continuous score and by adherence categories) and dietary components. UPF intake represented 35.9% of the TEI and was higher on weekdays (vs. weekends), among female adolescents (vs males), urban areas (vs. rural), and higher socioeconomic status. UPF were consumed mostly as snacks (43.5%), in the morning: (58.5%) and afternoon (41.5%). Each 10-percentage-point increase in the total UPF energy contribution was associated with -0.44 (SE = 0.04; P < .0001) lower TCRAD score. UPF was inversely associated with fiber and beneficial micronutrients, and directly associated with added sugars and trans fats. The multivariable-adjusted UPF intake was lower at moderate (38.5%, P < .0001) and high (29.9%, P < .0001) adherence to the TCRAD, compared with low adherence (43.9%). Our results support widespread trends of UPF displacing healthy diets. Strategies to reduce UPF consumption, especially during school hours, and encourage healthy traditional diets, are needed for Costa Rican adolescents.
