On average, UPF represents 30% of the total daily calories consumed by Brazilian adolescents. A large UPF consumption implies a large consumption of sodium, saturated and trans fat and a small intake of protein, fiber, vitamins, and minerals. After adjusting for confounding variables, we found that LDL-c is the cardiometabolic risk more associated with UPF consumption. We also observed an inverse association with HDL-c levels.
A systematic review (34) also observed an increase in LDL-c concentration among adolescents who consume more UPFs. It seems that saturated and trans fats found in UPFs are associated with a proatherogenic lipid profile (35). High consumption of saturated fats can increase LDL-c concentrations (36). Therefore, it is recommended to limit their consumption to 10% of the total caloric value (37). In our study, the average consumption of saturated fats by those in the highest tertile of UPF consumption represented more than 12% of the total caloric value, which may contribute to the change in the LDL-c fraction. On the other hand, trans fats, besides inducing an increase in LDL-c values, may also be associated with a reduction in HDL-c concentrations (37, 38).
Our results regarding the association between UPF consumption and low HDL-c differ from previous studies (39–41) because we observed a protective factor among those with higher UPF consumption. These results can be partially explained by the participants’ age, which were less exposed to the consumption of UPF, and that period might not be enough to change HDL-c values. Moreover, those with a higher UPF consumption also had a favorable profile for a higher prevalence of high HDL-c: female, having low/normal weight, non-smoker, and physically active for more than 420 min per week. From another perspective, studies show that HDL-c levels have an important genetic contribution (61) and population differences have already been documented (62, 63), suggesting that the cutoff points that define low and high levels of HDL-c can vary. In any case, longitudinal studies help understanding the relationship between UPF consumption and lipid profile in adolescence are needed.
The literature reviews—mostly from cross-sectional studies—show that high UPF consumption relates to increased body weight (43–46) and a higher overweight and obesity prevalence (47). In contrast, a sample of 1,039 Brazilian adolescents participating in the Estudo Longitudinal de Avaliação Nutricional de Adolescentes (ELANA)—who were followed for three years to assess the impact of UPF consumption on adiposity indicators—did not confirm the hypothesis that high UPF consumption is associated with weight gain in adolescents (48). In our study, the association between UPF consumption and overweight/obesity overlaps the unit after adjusting for total energy intake. A study shows that young people with excess body fat tend to underestimate their caloric intake (49), an issue that may be even greater concerning UPFs. Because of its easy consumption, teenagers may forget to not eat them, hindering their weight loss diet. Finally, the data collected in ERICA do not allow us to assess the adolescents’ diet practice at the time of the study, so we cannot evaluate the hypothesis that the lower consumption of UPF among adolescents with excess weight is due to diets.
Our study found no association between UPF consumption and most cardiometabolic risk factors analyzed. We highlight that the short time of UPF exposure and the expectation that most adolescents have a healthy cardiometabolic profile may have contributed to our results. However, unhealthy habits beginning in adolescence can continue into adulthood, and long-term exposure can hinder adulthood healthiness (50–56). The long-term impact of food additives used in the formulation of UPFs is also unknown. Additionally, the increase in UPF consumption can lead to a consequent reduction of in natura and minimally processed foods consumption, which are essential for a diet rich in vitamins, minerals, and fiber (57).
Our observations may have implications for public health since UPF consumption corresponds to an average of 1/3 of the calories consumed by adolescents. A diet imbalance and an increase in the high LDL-c prevalence occur among those with higher UPFs consumption. Longitudinal studies reinforce the importance of reducing the consumption of nutrients found in UPF, such as sodium (58) and saturated fats (59), to prevent cardiovascular disease and to control LDL-c levels (60). Thus, strategies to limit UPF consumption and studies aiming to establish an acceptable range of UPF consumption among adolescents should be encouraged since UPF consumption tends to remain part of the diet of most individuals, tending to increase over time in the absence of interventions.
The sample of Brazilian adolescent population from the whole country—which were interviewed by trained researchers, minimizing measurement errors—and all biochemical analyses performed in a single laboratory, are the strengths of our study. However, this study also has some limitations, such as using data from a single 24-hour food recall, which may have generated a report of food consumption that differs from the usual diet. Furthermore, we did not evaluate on-weekend consumption, which might underestimate the UPF consumption. Even when reports of culinary preparations were needed, we cannot specify the amounts of each ingredient used in the preparation, though illustrations of homemade measurements tests had been used to try to reduce the imprecision of the reports. Finally, as this is a cross-sectional study, it is not possible to exclude the possibility of reverse causality in the associations, but we believe that changes in food consumption precede the development of cardiovascular risk factors, an exception may be the presence of overweight/obesity and pre-existing morbidities that can stimulate diets.