Hydration Biomarkers and Water Intake in 3-13 year-old boys

Background/Introduction: Hydration is an important aspect of health in children. Despite being important, limited information is available regarding children’s water intake and hydration. Interestingly, most studies assess hydration status based on a single random urine sample instead of a 24-h one. Purpose: The aim of this study was to examine the prevalence of dehydration and water intake in boys 3 to 13 years-old. Methods: Forty-six healthy boys were recruited for the study. Each subject recorded food and fluid intake in a diary on a Saturday and Sunday. They also collected their 24-h urine on Sunday. The 24-h sample was analyzed for urine volume, osmolality (freezing point depression), color (8 color scale) and urine specific gravity (refractometry). The nutrition data system for research software was used to calculate water intake from food from diaries. Water intake data were presented as the average of Saturday and Sunday. Physical activity was estimated via the international physical activity questionnaire and data are presented as total MET-min per week. Mean values between groups were compared by student’s t-test. Data were analyzed with JMP statistical analysis software. Results: Eighteen of the 46 boys (39%) were dehydrated (urine osmolality \u3e800 mOsm/kg) and 29 of them (63%) did not meet the Institute of Medicine’s dietary guidelines for daily water intake. The 24-h urine osmolality for euhydrated and dehydrated boys was 530±150 and 967±140 mOsm/kg (P\u3c0.05), respectively. Physical activity was not different between dehydrated (5,506±4,941 MET-min/wk) and euhydrated boys (4,575±4,338 MET-min/week; P\u3e0.05). Dehydrated boys had lower total water intake (1,661±759 mL) than euhydrated ones (1,937±1,661 mL). Conclusion: These preliminary data suggests that the majority of 3-13 year-old boys fail to meet the water intake recommendations and 4 out of 10 are hypohydrated. More data are needed to examine the factors that influence these observations