Background: Water is vital for humans' survival and general health, which is involved in various metabolic activities.
Objectives: The aim of this study was to investigate the variation in urine metabolome and associated metabolic pathways among people with different hydration states.
Methods: A metabolomic analysis was conducted using 24-h urine samples collected during a cross-sectional study on fluid intake behavior from December 9 to 11, 2021, in Hebei, China. Subjects were divided into the optimal hydration (OH, ≤500 mOsm/kg, = 21), middle hydration (500-800 mOsm/kg, = 33), and hypohydration groups (HH, >800 mOsm/kg, = 13) based on the 3-d average 24-h urine osmolality. Collected 24-h urine samples from 67 subjects (43 males and 34 females) were analyzed for urine metabolome using liquid chromatography-MS.
Results: The untargeted metabolomic analysis yielded 1055 metabolites by peak intensities. Integrating the results of the orthogonal projections to latent structures discriminant analysis and fold change test, 115 differential metabolites between the OH and HH groups, including phospholipids (PLs) and lysophospholipids, were identified. Among the 115 metabolites identified as differential metabolites, 85 were recorded by the Human Metabolome Database and uploaded to the Kyoto Encyclopedia of Genes and Genomes databases for pathway analysis. Twenty-one metabolic pathways were recognized. Phenylalanine metabolism (0.50, = 0.007), phenylalanine, tyrosine, and tryptophan biosynthesis (0.50, = 0.051), glycerophospholipid metabolism (0.31, < 0.001), sphingolipid metabolism (0.27, = 0.029), and cysteine and methionine metabolism (0.10, = 0.066) had the leading pathway impacts.
Conclusions: We found variations in the urinary PLs and amino acids among subjects with different hydration states. Pathways associated with these differential metabolites could further impact various physiologic and pathologic functions. A more comprehensive and in-depth investigation of the physiologic and pathologic impact of the hydration state and the underlying mechanisms to elucidate and advocate optimal fluid intake habits is needed.This trial was registered at Chinese Clinical Trial Registry as ChiCTR2100045268.
