Drinking patterns and hydration biomarkers among young adults with different levels of habitual total drinking fluids intake in Baoding, Hebei Province, China: a cross-sectional study

BACKGROUND: The purposes were to investigate the drinking patterns and hydration biomarkers among young adults with different levels of habitual total drinking fluids intake. METHODS: A cross-sectional study was conducted among 159 young adults aged 18–23 years in Baoding, China. Total drinking fluids and water from food were assessed by 7-day 24-h fluid intake questionnaire and duplicate portion method, respectively. The osmolality and electrolyte concentrations of the 24 h urine and fasting blood samples were tested. Differences in LD(1) (low drinker), LD(2), LD(3) and HD (high drinker) groups, stratified according to the quartiles of total drinking fluids, were compared using one-way ANOVA, Kruskal-Wallis H test and chi-square test. RESULTS: A total of 156 participants (80 males and 76 females) completed the study. HD group had greater amounts of TWI (Total Water Intake), water from food, higher and lower contributions of total drinking fluids and water from food to TWI, respectively, than LD(1), LD(2) and LD(3) groups (p < 0.05). Participants in HD group had higher amounts of water and water from dishes than participants in LD(1), LD(2) and LD(3) groups (p < 0.05). No significant differences were found in the contributions of different fluids to total drinking fluids within the four groups (p > 0.05). The osmolality of urine was 59–143 mOsm/kg higher in LD(1) than that in LD(2), LD(3) and HD group (p < 0.05). The percentage of participants in optimal hydration status increased from 12.8% in LD(1) group to 56.4% in HD group (p < 0.05). HD and LD(3) groups had 386~793 higher volumes of urine than that of LD(1) and LD(2) groups (p < 0.05). Differences were found in the concentrations of electrolytes among the four groups (p < 0.05). No significant differences were found in the plasma biomarkers (p > 0.05), with the exception of higher concentration of Mg in LD(3) and HD groups than that in LD(1) and LD(2) groups (p < 0.05). CONCLUSIONS: Participants with higher total drinking fluids had better drinking pattern and hydration status. Interventions should be undertaken to advise adults to have adequate total drinking fluids, in order to keep in optimal hydration status. TRIAL REGISTRATION: The registration number was ChiCTR-ROC-17010320, which was registered on the Chinese clinical trial registry.