Fluid consumption, total water intake and first morning urine osmolality in Spanish adolescents from Zaragoza: data from the HELENA study

Abstract

Background/objectives: The objective of the study is to describe the hydration status and to assess the main food- and/or fluid intake-associated factors in healthy adolescents.

Subjects/methods: A total of 194 adolescents from the city of Zaragoza aged 12.5-17.5 years (99 males) participating in the 'Healthy Lifestyle in Europe by Nutrition in Adolescence' (HELENA) cross-sectional study were included. First morning urine was collected, and osmolality was determined by freezing point depression osmometer. A self-reported computer-based 24-h dietary recall was applied the same day of the urine collection. Analysis of variance, Kruskal-Wallis procedure or Pearson's χ(2) analyses was used to examine the group associations.

Results: Seventy-one percent of adolescents did not meet the European Food Safety Agency (EFSA) recommendations for average total water intake (TWI), and 68% had high first morning urine osmolality values. TWI and the proportion of those meeting EFSA reference values significantly (P<0.05) decreased with increased osmolality. Males who met the EFSA recommendations consumed significantly (P<0.05) more plain water (1035.13 vs 582.68 ml) and dairy drinks (368.13 vs 226.68 ml) than those who did not. In females, the consumption of water (1359.41 vs 620.44 ml) and sugar-sweetened beverages (214.61 vs 127.42 ml) was significantly higher in those meeting the EFSA recommendations than in those who did not. First morning urine osmolality was associated with vegetables (unstandardized β: -0.6; 95% confidence interval (CI): -1.02 and -0.18) and fruits intake (β: -0.41; 95% CI: -0.63 and -0.19) in males and with dairy drinks (β: -0.39; 95% CI: -0.76 and -0.02) and fruits (β: -0.41; 95% CI: -0.73 and -0.10) in females.

Conclusions: There was a high prevalence of inadequate TWI and high urine osmolality among these Spanish adolescents. Lower urine osmolality was associated with higher consumption of vegetables in males, dairy drinks in females and fruits in both males and females.