Ultra-processed food intake, sources, and associations with sociodemographic factors in New Zealand adolescents : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand

Abstract

Background: Adolescence is a critical period for establishing dietary patterns that can influence long term health outcomes. Ultra-processed foods (UPFs) are becoming increasingly prevalent within the modern diet, with research establishing the negative impacts of UPFs on several health markers and outcomes across populations. Understanding how UPF intake varies by sociodemographic characteristics is essential for informing policies and shaping food environments that support healthier choices. However, current data on UPF intake and sociodemographic factors amongst New Zealand (NZ) adolescents does not exist. Aims and objectives: This research aimed to investigate UPF intake and sources of UPFs in NZ adolescents and associations with sociodemographic factors including sex, age, school region, school area, and school lunch programme eligibility. Methods: The data for this research was obtained through the Te Rourou Kai o Ngā Rangatahi: Eating Patterns of Young People in NZ study. This cross-sectional study gathered data from 631 adolescents in Years 7-13 (aged between 11-19 years) in the Auckland, Waikato and Bay of Plenty (BOP) regions of NZ. Dietary data was collected through the Intake24 electronic software, using the multiple pass method, and demographic information was collected via an online questionnaire. Foods were linked to the NZ Food Composition Database and categorised according to NOVA, as either (1) whole or minimally processed foods, (2) processed culinary ingredients, (3) processed foods, or (4) ultra-processed foods. UPFs were further categorised into food groups to determine the top contributors to overall UPF intake. Differences in UPF (as a percentage of total daily energy intake (TDEI)) across sociodemographic variables were assessed using one-way ANOVA or independent t-tests. Tukey’s Honest Significant Difference (HSD) test was used for post hoc comparisons. Results: Participants (n=631) had a mean UPF intake of 892 ± 766 g/day, 5435 ± 3592 kJ/day, contributing to 62.5 ± 25.3% of TDEI. The top food group contributors to UPF energy were fast foods/takeaways (12.2 ± 19.9%), bread and bread products (7.9 ± 12.2%), and biscuits, cakes, desserts (7.5 ±12.2%). UPF intake (%TDEI) was higher among females compared to males (64.4% vs. 58.1% of TDEI, p=0.01), participants in the Waikato region vs. Auckland (68.2% vs. 60.2%, p=0.008), and participants from medium and small areas compared to major and large urban areas (67.2% vs. 61.3%, p=0.0043). Those eligible for the school lunch programme consumed less energy from UPFs compared to those ineligible (60.0% vs. 65.6%, p=0.005). Conclusion: UPFs contribute a high proportion of energy to adolescent’s TDEI in NZ. Fast foods/takeaways; bread and bread products; and biscuits, cakes, and desserts are the largest food group contributors to total UPF intake. Our findings suggest that female adolescents, those living in the Waikato region, and residing in any size urban area consumed significantly greater energy from UPFs. Participants eligible for the school lunch programme consumed less energy from UPFs. Further research is required using multiple 24-hour recalls to account for habitual intake as well as investigating the influence of food environments, food marketing and regional access on UPF consumption in NZ adolescents.