title: Plasma choline metabolites associate with metabolic stress among young overweight men in a genotype-specific manner.
abstract: OBJECTIVE
  We aimed to test the hypotheses that (i) plasma choline metabolites differ between normal (body mass index (BMI)<25 kg m(-2)) and overweight (BMI 25 kg m(-2)) men, and (ii) an elevated BMI alters associations between plasma choline metabolites and indicators of metabolic stress.
  
  
  METHODS
  This was a cross-sectional study. A one-time fasting blood sample was obtained for measurements of the choline metabolites and metabolic stress indicators (that is, serum alanine aminotransferase (ALT), glucose, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides and homocysteine), and for genotype determination.
  
  
  METHODS
  The analysis was conducted with 237 Mexican American men with a median age of 22 years.
  
  
  RESULTS
  Compared with men with a normal BMI (n=98), those with an elevated BMI (n=139) had 6% lower (P=0.049) plasma betaine and an 11% lower (P=0.002) plasma betaine to choline ratio. Among men with an elevated BMI, plasma betaine and the plasma betaine to choline ratio positively associated (P0.044) with a favorable serum cholesterol profile, and inversely associated (P=0.001) with serum ALT, a marker of liver dysfunction. The phosphatidylethanolamine N-methyltransferase (PEMT) 5465GA (rs7946) genotype interacted (P0.007) with the plasma betaine to choline ratio to modulate indicators of metabolic stress with stronger inverse associations observed among overweight men with the PEMT 5465GG genotype.
  
  
  CONCLUSIONS
  Plasma choline metabolites predict metabolic stress among overweight men often in a genotype-specific manner. The diminished betaine among overweight men coupled with the inverse association between betaine and metabolic stress suggest that betaine supplementation may be effective in mitigating some of the metabolic insults arising from lipid overload.
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
authors.forename: J
authors.initials: J
authors.lastname: Yan
authors.forename: L B
authors.initials: LB
authors.lastname: Winter
authors.forename: B
authors.initials: B
authors.lastname: Burns-Whitmore
authors.forename: F
authors.initials: F
authors.lastname: Vermeylen
authors.forename: M A
authors.initials: MA
authors.lastname: Caudill