The association between hydration status and body composition in healthy children and adolescents.

OBJECTIVES: Children 10-20 years old in the US are currently obese, showing suboptimal hydration as 60% fail to meet the US Dietary Reference Intakes for water. Studies have shown a significant inverse association between hydration status and body composition in children, although most failed to use the Dual-X-Ray Absorptiometry Scan (DEXA), the gold standard for body composition. Limited studies used an objective marker to measure hydration, such as urine specific gravity (USG) from a 24-h urine collection. Therefore, this study aimed to examine the association between hydration status (measured from USG in a 24-h urine sample and assessed from three 24-h dietary recalls) and body fat % and lean mass (assessed from a DEXA scan) in children (10-13 years, n=34) and adolescents (18-20 years, n=34). METHODS: Body composition was measured using DEXA, total water intake (mL/d) was assessed from three 24-h dietary recalls and analyzed using the Nutrition Data System for Research (NDSR). Hydration status was objectively measured using USG via 24-h urine collection. RESULTS: Overall body fat % was 31.7 ± 7.31, total water intake was 1746 ± 762.0 mL/d, and USG score was 1.020 ± 0.011 uG. Linear regressions showed significance between total water intake and lean mass (B=12.2, p<0.05). Logistic regressions showed no significant association between body composition and USG and total water intake. CONCLUSIONS: Findings showed total water intake was significantly associated with lean mass. Future research should be conducted to explore other objective markers of hydration and with a larger sample.

The association between hydration status and total fluid intake in healthy children and adolescents.

BACKGROUND: Children 10-20 years old in the US have suboptimal hydration status. Hydration is best assessed using an objective marker, such as urine specific gravity (USG) from a 24-h urine collection. There are limited studies associating hydration from an objective marker with intake assessed from 24-h recalls in children. The objective of the study was to evaluate which foods or beverages are significantly associated with an objective marker of hydration (USG) in a sample of children and adolescents. METHODS: Intake was assessed from three 24-h dietary recalls and analyzed using the Nutrition Data System for Research (NDSR). Hydration status was objectively measured using USG via 24-h urine collection. Associations were assessed with logistic regressions. RESULTS: A total of 68 children and adolescents were recruited (50% females). Average overall USG score was 1.020 ± 0.011 uG with 39.7% categorized as dehydrated. After adjusting for age and sex, fruit juice (1.009, 95% CI: 1.001, 1.018) and all beverages (1.001, 95% CI: 1.000, 1.002) were significantly associated with higher odds of being euhydrated. CONCLUSIONS: The main predictors of hydration were fruit juice and all beverages intake. Future research should be conducted to explore differences in dietary patterns in a larger, more generalizable sample. IMPACT: Findings showed that the main predictors of hydration were water and fruit juice intake in children and water intake in adolescents in southern Florida. This is the first study to examine which type of beverages and foods are associated with USG, an objective marker of hydration status, in US children and adolescents. Provides further insight into the use of objective markers to assess hydration status, while providing data to assist epidemiological studies that may have limited resources to examine beverages and foods that contribute to hydration.