Iron intakes and food sources of iron in New Zealand adolescent females

Abstract

Background: Adolescent females may be at risk of poor iron status even when following a diet that includes iron-rich meat, due to a combination of high requirements for growth, expanding blood volume, and the onset of menstruation. No studies have investigated the dietary intakes and main food sources of iron in New Zealand (NZ) adolescent females 15-18 years of age since the 2008/09 Adult Nutrition Survey (ANS) 10 years ago. An understanding of the current iron intakes of adolescent females is important for the purpose of informing up to date health-based recommendations on adolescent diet. Objectives: The aim of this study was to describe the dietary intakes and main food sources of iron in female adolescents 15-18 years of age in New Zealand. The specific objectives were to: 1) determine the iron intake of female adolescents 15-18 years of age in New Zealand, 2) assess the prevalence of inadequate and potentially excessive intakes of iron using dietary and supplement intake data in female adolescents in New Zealand, and 3) describe the main food sources that are contributing to the iron intakes of female adolescents in New Zealand. Design: The Survey of Nutrition Dietary Assessment and Lifestyle (SuNDiAL) study was a cross-sectional survey conducted with 145 female high school students aged 15-18 years from seven cities in New Zealand. This thesis used questionnaire data including: demographics and dietary habits, and two 24-hour recalls collected by Master of Dietetic (MDiet) students, including the Candidate, to determine participants’ dietary intakes and main food sources of iron. The 24-hour recalls were entered into a web-based dietary software programme, “FoodWorks”, to determine the energy and iron content of the diet. Results: A total of 145 female adolescents with a mean age of 16.7 years participated in the SuNDiAL study. The mean dietary iron intake and median total iron intake (i.e. intake from diet and supplements) were 11.8mg/day. The prevalence of inadequate dietary iron intakes was 20.8% (20.0% for total iron intake), while the prevalence of potentially excessive total iron intakes was just 1.5% with 2 participants having total iron intakes above the upper level of intake (UL). The main food sources contributing to the participants’ iron intakes were the “bread” food group providing 10% of dietary iron, followed by “grains and pasta” (10%), and “breakfast cereals” (9%). Conclusion: The results from the present study suggest that dietary iron intakes may have increased, and the prevalence of inadequate intakes decreased, over the past decade. However, these data should not be used in isolation of iron status data and need to be interpreted with caution as they are not representative of the whole NZ adolescent female population.