Exploring ultra-processed food consumption and associations with nutrient intake in New Zealand adolescents
Abstract
Despite concerns about high consumption of ultra-processed foods (UPFs) among New Zealand adolescents, there has been no formal quantification of their intake. This study is the first to assess UPF consumption in this population and examine its contribution to daily nutrient intake. A cross-sectional study was conducted involving students in Years 7–13 (approximately 10 years and older) from schools in Auckland, Bay of Plenty, and Waikato. Data collection took place in classroom settings during school terms two and three of 2024. Dietary intake was recorded using Intake24, an electronic 24-hour dietary recall tool adapted for the New Zealand context. All foods consumed—including ingredients in mixed meals—were classified into four categories using the NOVA system: Unprocessed or Minimally Processed, Processed Culinary Ingredients, Processed, and Ultra-Processed(1). The proportion of daily energy derived from UPFs was calculated. Participants were divided into tertiles based on UPF consumption, and nutrient intake across these groups was compared using one-way ANOVA. Dietary data were collected from 631 adolescents across 16 schools, encompassing 1,385 unique food items. UPFs accounted for 62.5 ± 25.5% (mean ± SD) of total daily energy intake. While overall energy intake did not differ significantly across UPF consumption tertiles, notable differences in nutrient intake were observed. After adjustment for energy intake and sex, adolescents in the highest UPF tertile had significantly lower intakes of protein (P<0.001), fibre (P=0.04), beta-carotene (P<0.001), magnesium (P<0.001), potassium (P<0.001), zinc (P<0.001), phosphorus (P<0.001), iron (P=0.03) and Vitamin E (p<0.001). Ultra-processed food intake was associated with significantly higher intakes of carbohydrates (P=0.005), saturated fat (P<0.001), sugar (P<0.001) and sodium (P<0.01). These findings provide foundational insight into the extent of UPF consumption among New Zealand adolescents and its impact on diet quality. The proportion of energy derived from UPFs aligns closely with international data from the United States (67%) and the United Kingdom (66%). Further analysis will explore the specific types of UPFs consumed, their sources, and the social contexts in which they are eaten.