Measuring Children’s Sodium and Potassium Intakes in New Zealand

Abstract

Background: The totality of current research suggest that both sodium and potassium play a pivotal role in blood pressure (BP) management. Maintaining a healthy balance of sodium and potassium in the diet is important for long term health outcomes. In 2013, a commitment was made by World Health Organisation (WHO) member states, including New Zealand (NZ), to achieve a 30% relative reduction in population sodium intake towards 2,000mg (5g salt) per day by 2025. Although five years has passed since the commitment was made, little has been done towards achieving or monitoring progress towards the target in NZ. Furthermore, monitoring salt intake in NZ has focused primarily on adult populations creating a knowledge gap regarding children and their intake levels. Objective: The overall aim of this thesis was to review the literature on the dietary intake and food sources of sodium and potassium in high income countries and to measure dietary intakes of sodium and potassium and the main food sources of these electrolytes in a group of NZ school children. Methods: A review of scientific and grey literature was undertaken to determine sodium and potassium intakes and their food sources for children in high income countries. A study of NZ school children's reported dietary intake of food sources of sodium and potassium was also conducted within the framework of an existing pilot study (n=27). Children from an Auckland primary school were asked to complete a gold standard 24-hour urine collection and a 24- hour diet recall. The latter was collected by the student using a web-based dietary assessment tool called Intake24. Dietary data were supplemented with brands-specific information from the Nutritrack database. Sodium and potassium intakes and food sources of these electrolytes from the dietary record data were reported. A comparison of total intakes between dietary intake data and 24-hour urinary sodium excretion data was also completed using Bland-Altman plots and one sample T-Test procedures. Results: 23 studies published between 2002-2017 were included in the literature review. The review reported that children across 13 countries were consuming excess sodium and insufficient potassium, compared to respective nutrition guidelines and the WHO recommendations. Food sources of sodium (cereal based products, meat and dairy), and potassium (dairy, fruits and vegetables and cereal based products) were relatively consistent across the different countries.