24h-Sodium excretion and hydration status in children and adolescents - Results of the DONALD Study

Background & aims: To describe actual data on intake, sources, age and time trends of urinary sodium excretion and to analyze the potential association between urinary sodium excretion and hydration status respective beverage consumption in a sample of healthy German children and adolescents. Methods: Data of 1575 24 h-urine samples and weighed dietary records of 499 children (249 boys) aged 4 -18 years of the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study collected in 2003-2009 were analyzed using linear mixed effects regression models. Free water reserve (FWR, measured urine volume (ml/24 h) minus the obligatory urine volume (ml/24 h)) was used as a marker for hydration status. Results: Urinary sodium excretion was between 1.4 g/day and 3.2 g/day, showing a positive age trend but remained stable during the study period. In girls, there was a significant positive association between salt excretion and FWR (p = 0.04). Per g/MJ urinary sodium excretion, beverage intake increased by 0.05 g/MJ (boys) or 0.08 g/MJ (girls). Conclusion: Hydration status was not affected by salt intake in this sample of healthy children and adolescents in a western life style, due to a compensatory increase in beverage consumption. (C) 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.