title: Inter- and intra-individual variations of urinary endogenous metabolites in healthy male college students using (1)H NMR spectroscopy.
abstract: BACKGROUND
  Most human metabolomics studies have shown that spectral outputs of (1)H nuclear magnetic resonance fingerprinting are strongly influenced by inter- and intra-individual variations; however, few studies have been performed to evaluate the inter- and intra-individual variations in urinary endogenous metabolites.
  
  
  METHODS
  We recruited 30 male college students to evaluate the factors affecting intra- and inter-individual variations in urinary endogenous metabolites. Statistical analysis for variations in urinary metabolites was performed after eliminating outliers found in principal component analysis (PCA) plots.
  
  
  RESULTS
  Inter-individual variations were relatively low for 2-oxoglutarate, succinate, citrate, dimethylglycine, and taurine, but high for trimethylaminoxide (TMAO), hippurate, and lactate. Intra-individual variations for 2-oxoglutarate, citrate, dimethylglycine, and taurine were relatively low, but high for TMAO and hippurate. The factors affecting inter-individual variation of lactate were age, body mass index, beverages, and alcohol, whereas the factors affecting intra-individual variation of lactate were age and fish. Kim Chi intake affected the inter-individual variation of succinate, citrate, TMAO, and hippurate; however, it did not affect the intra-individual variation of endogenous metabolites.
  
  
  CONCLUSIONS
  Our results showed that inter- and intra-individual variations in urinary endogenous metabolites were very large, and significant factors affecting inter- and intra-individual variation were diverse, even after eliminating outliers in PCA analysis.
authors.affiliation: Department of Public Health, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Eun
authors.initials: E
authors.lastname: Mi Park
authors.forename: Eunil
authors.initials: E
authors.lastname: Lee
authors.forename: Hyun
authors.initials: H
authors.lastname: Jin Joo
authors.forename: Eunha
authors.initials: E
authors.lastname: Oh
authors.forename: Joohyun
authors.initials: J
authors.lastname: Lee
authors.forename: Ji-Sung
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002264:Carboxylic Acids / Q000652:urine*; D006262:Health; D006801:Humans; D007656:Ketoglutaric Acids / Q000652:urine*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008744:Methylamines / Q000652:urine*; D025341:Principal Component Analysis; D011522:Protons; D015203:Reproducibility of Results; D012521:Sarcosine / Q000031:analogs & derivatives* / Q000652:urine; D012680:Sensitivity and Specificity; D013654:Taurine / Q000652:urine*
chemical_list: D002264:Carboxylic Acids; D007656:Ketoglutaric Acids; D008744:Methylamines; D011522:Protons; D013654:Taurine; C025138:dimethylglycine; D012521:Sarcosine