Water from Food in Young Chinese Adults: Patterns, Determinants, and Public Health Implications: A Cross-Sectional Study Across the Seven Geographic Regions

Adequate hydration is essential for health, yet the contribution of water from food (WFF) to total water intake (TWI) and its determinants remain unclear in China. This study quantified WFF and explored factors influencing its variation among young Chinese adults. A multicentre cross-sectional survey was conducted in May-June 2023 among 947 healthy adults aged 18-25 years from seven regions of China. WFF was measured using three-day duplicate food portions, and drinking fluid intake was recorded with a validated 24 h diary. Sociodemographic, dietary, behavioral, and psychological data were collected using standardized instruments. Multivariable linear regression, stratified by sex and age, examined associations with WFF and its proportion of TWI. On average, WFF accounted for 38.0% of TWI, with regional variation from 33.5% in southern China to 44.3% in eastern China. Higher daily intake of energy, salt, and carbohydrate intakes were each positively associated with greater WFF, while carbohydrate intake seemed to betas the strongest predictor of a higher proportion of WFF. Younger age and elevated anxiety showed modest independent associations. These findings indicate that WFF contributes substantially to hydration in Chinese young adults, primarily driven by dietary composition. Recognizing WFF in hydration guidelines could improve population assessments and inform evidence-based nutrition strategies in China and other high-moisture diet regions.