title: Associations among circulating branched-chain amino acids and tyrosine with muscle volume and glucose metabolism in individuals without diabetes.
abstract: OBJECTIVE
  Amino acid metabolites, including branched-chain amino acids (BCAA) and tyrosine (Tyr), affect glucose metabolism. The effects of BCAA on insulin resistance in patients with diabetes seem to conflict with mechanisms determined in animal models and cultured cells. The aim of this study was to clarify the controversy surrounding the effects of BCAA by investigating the physiological effects of BCAA and Tyr on glucose metabolism in healthy community dwellers.
  
  
  METHODS
  We investigated associations among BCAA and Tyr and metabolic parameters in 78 residents (median age, 52 y) of Mie, Japan, who did not have prediabetes, diabetes, or a body mass index >30 kg/m(2).
  
  
  RESULTS
  Muscle volume, serum BCAA, and Tyr levels were higher in men than in women (n = 32 and 46, respectively; all P < 0.0001). Stepwise multiple regression analysis associated BCAA positively with muscle volume (regression coefficient/t/p/95% confidence interval, 281.8/3.7/0.0004/129.7-433.8), fasting blood glucose (FBG; 12699.4/3.22/0.0020/4830.9-20567.8), fasting immunoreactive insulin (IRI; 8505.1/2.75/0.0078/2322.5-14687.6), and homeostasis model assessment of β-cell function (HOMA-β; 893.6/2.58/0.0122/201.8-1585.5), and negatively with the HOMA-insulin resistance (HOMA-IR; -9294.1/-2.89/0.0052/-15711.0 to -2877.1). Tyr positively correlated with fasting IRI (26/2.77/0.0072/7.3-44.7).
  
  
  CONCLUSIONS
  Insulin sensitivity and muscle volume are positively associated with BCAA in individuals without diabetes. In turn, BCAA correlate with increased FBG and fasting IRI levels. Tyr correlated with fasting IRI, but not with insulin sensitivity.
authors.affiliation: Faculty of Health Science, Suzuka University of Medical Science, Suzuka, Japan; Department of Gastroenterology and Hepatology, Mie University Graduate School of Medicine, Tsu, Japan; Center for Physical and Mental Health, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Honda
authors.affiliation: Department of Gastroenterology and Hepatology, Mie University Graduate School of Medicine, Tsu, Japan; Center for Physical and Mental Health, Mie University Graduate School of Medicine, Tsu, Japan. Electronic address: yoshinao@hac.mie-u.ac.jp.
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Department of Health and Physical Education, Mie University Faculty of Education, Tsu, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Togashi
authors.affiliation: Department of Gastroenterology and Hepatology, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Department of Gastroenterology and Hepatology, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Motoh
authors.initials: M
authors.lastname: Iwasa
authors.affiliation: Center for Physical and Mental Health, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Taguchi
authors.affiliation: Department of Gastroenterology and Hepatology, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Takei
authors.affiliation: Center for Physical and Mental Health, Mie University Graduate School of Medicine, Tsu, Japan; Yokkaichi-Hazu Medical Center, Japan Community Healthcare Organization, Yokkaichi, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Sumida
mesh_terms: D000328:Adult; D000597:Amino Acids, Branched-Chain / Q000097:blood*; D001786:Blood Glucose / Q000032:analysis*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007564:Japan; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D024510:Muscle Development; D012044:Regression Analysis; D012727:Sex Characteristics; D018709:Statistics, Nonparametric; D014443:Tyrosine / Q000097:blood*
chemical_list: D000597:Amino Acids, Branched-Chain; D001786:Blood Glucose; D007328:Insulin; D014443:Tyrosine
keywords: Fasting blood glucose; Insulin resistance; Spearman's test; Stepwise multiple regression analysis; β-cell function