title: The association between carbon and nitrogen stable isotope ratios of human hair and metabolic syndrome.
abstract: BACKGROUND
  It has been reported that stable isotope ratios can be used as biomarkers for animal protein intake. Meat consumption and high protein intake could be risk factors for metabolic disorders. We investigated whether the stable isotope ratios of carbon and nitrogen are associated with metabolic syndrome.
  
  
  METHODS
  We conducted a cross-sectional study of 399 subjects (233 men and 166 women). Hair samples from 399 subjects were measured for stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N).
  
  
  RESULTS
  The δ(15)N values progressively increased with the number of components of the metabolic syndrome present in study subjects (P for trend 0.047). In multivariable models, δ(15)N values were positively associated with the presence of metabolic syndrome (odds ratio, 1.53; 95% confidence interval, 1.09-2.14), whereas δ(13)C values were not (odds ratio, 0.97; 95% confidence interval, 0.72-1.30). The odds ratio (95% confidence interval) for metabolic syndrome comparing the highest to the lowest quartiles of δ(15)N values was 2.64 (1.17-5.92).
  
  
  CONCLUSIONS
  The nitrogen, but not carbon, stable isotopic ratio of hair is independently associated with the presence of metabolic syndrome. The hair δ(15)N value might be a surrogate marker for clustering of risk factors in metabolic syndrome.
authors.affiliation: Department of Preventive Medicine, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea; Institute of Genomic Cohort, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea.
authors.forename: Jong-Ku
authors.initials: JK
authors.lastname: Park
authors.affiliation: Department of Preventive Medicine, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea; Institute of Genomic Cohort, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea. Electronic address: dodge@yonsei.ac.kr.
authors.forename: Song Vogue
authors.initials: SV
authors.lastname: Ahn
authors.affiliation: Department of Preventive Medicine, College of Medicine, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Mi Kyung
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Division of Earth and Environmental Science, Korea Basic Science Institute, Ochang 363-883, South Korea.
authors.forename: Kwang-Sik
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Department of Preventive Medicine, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea; Institute of Genomic Cohort, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea.
authors.forename: Sang-Baek
authors.initials: SB
authors.lastname: Koh
authors.affiliation: Division of Earth and Environmental Science, Korea Basic Science Institute, Ochang 363-883, South Korea.
authors.forename: Yeon-Sik
authors.initials: YS
authors.lastname: Bong
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D002247:Carbon Isotopes / Q000032:analysis*; D003430:Cross-Sectional Studies; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism*; D008875:Middle Aged; D009587:Nitrogen Isotopes / Q000032:analysis*; D056910:Republic of Korea
chemical_list: D015415:Biomarkers; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes
keywords: Carbon; Metabolic syndrome; Nitrogen; Stable isotope ratio