Nutrient intake of New Zealand adolescents aged 14-18 years in the Auckland, Bay of Plenty and Waikato regions of New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy, Massey University, Albany, New Zealand

Abstract

Background. Adolescence represents a crucial stage of rapid physical, cognitive, and emotional development, during which nutrient requirements substantially increase to support optimal growth and maturation. Despite this, available data on the dietary patterns and nutritional status of New Zealand (NZ) adolescents are limited and largely outdated, hindering an accurate evaluation of nutrient adequacy and potential deficiencies within this population. Aims and Objectives This research aims to investigate the current nutrient status of NZ adolescents and compare their intake to their nutrient reference values and assess their adherence to dietary recommendations. Methods. Data was obtained from Te Rourou o Ngā Rangatahi: Eating Patterns of Young People in New Zealand, a cross-sectional survey investigating the dietary habits of adolescents. The study included 527 secondary school students aged 14–19 years from the Auckland, Bay of Plenty, and Waikato regions. Dietary intake was collected using Intake24, a web-based multiple-pass 24-hour dietary recall tool, along with an online demographic questionnaire. Nutrient intakes were compared with the Australian and New Zealand Nutrient Reference Values (NRVs) to assess dietary adequacy. Results. Female participants (n=370, 70.2%) demonstrated greater adherence to macronutrient recommendations than males. Mean intakes of protein, carbohydrate, and fat exceeded recommended levels, while fibre intake remained below guidelines. Mean protein intake was 76.8 ± 44.3 g for females and 105.8 ± 61.6 g for males, with 97.8% of females and 98% of males meeting the recommended percentage of energy from protein. Fibre intake averaged 19.2 ± 11.2 g for females and 20.7 ± 12.5 g for males, below the recommended 22 g and 28 g, respectively, indicating low fruit and vegetable consumption. Only 9.7% of females and 7% of males met recommendations for saturated fat intake, with the majority exceeding the upper limit. Male participants demonstrated higher mean intakes across most micronutrients; however, several nutrients were identified as concerns. Mean calcium intake was 721.9 ± 463.6 mg/day for females and 868.3 ± 691.5 mg/day for males, with 20.3% and 31.2% meeting the Estimated Average Requirement (EAR), respectively. Iron intake averaged 9.8 ± 6.1 mg/day in females and 12.3 ± 8.0 mg/day in males, with 53.8% and 66.9% meeting the EAR. Vitamin A and vitamin E intakes were below recommendations for most participants, while magnesium and vitamin C also showed low adherence to the NRVs. Overall, both macronutrient imbalances and micronutrient inadequacies were evident among New Zealand adolescents. Conclusion. Overall, the findings highlight significant nutritional imbalances among New Zealand adolescents, characterised by excessive macronutrient intake and inadequate consumption of key micronutrients such as calcium, iron, vitamins A and E, magnesium, and vitamin C. These results underscore the need for updated national data and targeted public health strategies to improve dietary quality and address nutrient inadequacies within this population, such as education on the importance of adequate nutrition during adolescence and to foods that fuel their bodies.