title: European ancestry and resting metabolic rate in older African Americans.
abstract: OBJECTIVE
  Resting metabolic rate (RMR) contributes 60-80% of total energy expenditure and is consistently lower in populations of African descent compared with populations of European populations. Determination of European ancestry (EA) through single nucleotide polymorphism (SNP) analysis would provide an initial step for identifying genetic associations that contribute to low RMR. We sought to evaluate the association between RMR and EA in African Americans.
  
  
  METHODS
  RMR was measured by indirect calorimetry in 141 African American men and women (aged 74.7±3.0 years) enrolled in a substudy of the Health, Aging and Body Composition Study. Ancestry informative markers were used to estimate individual percent EA. Multivariate regression was used to assess the association between RMR and EA after adjustments for soft tissue fat-free mass (STFFM), fat mass, age, study site, physical activity level and sex.
  
  
  RESULTS
  Mean EA was 23.8±16% (range: 0.1-70.7%) and there were no differences by sex. Following adjustments, each percent EA was associated with a 1.6 kcal/day (95% Confidence interval: 0.42, 2.7 kcal/day) higher RMR (P=0.008). This equates to a 160 kcal/day lower RMR in a population of completely African ancestry, with one of completely European ancestry. Additional adjustment for trunk STFFM that partially accounts for high-metabolic rate organs did not affect this association.
  
  
  CONCLUSIONS
  EA in African Americans is strongly associated with higher RMR. The data suggest that population differences in RMR may be due to genetic variants.
authors.affiliation: Department of Aging and Geriatric Research, University of Florida, Institute on Aging, Gainesville, USA. tmanini@aging.ufl.edu
authors.forename: T M
authors.initials: TM
authors.lastname: Manini
authors.forename: K V
authors.initials: KV
authors.lastname: Patel
authors.forename: D C
authors.initials: DC
authors.lastname: Bauer
authors.forename: E
authors.initials: E
authors.lastname: Ziv
authors.forename: D A
authors.initials: DA
authors.lastname: Schoeller
authors.forename: D C
authors.initials: DC
authors.lastname: Mackey
authors.forename: R
authors.initials: R
authors.lastname: Li
authors.forename: A B
authors.initials: AB
authors.lastname: Newman
authors.forename: M
authors.initials: M
authors.lastname: Nalls
authors.forename: J M
authors.initials: JM
authors.lastname: Zmuda
authors.forename: T B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D001741:Black or African American / Q000235:genetics*; D000368:Aged; D001481:Basal Metabolism / Q000235:genetics*; D002153:Calorimetry, Indirect; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D044465:White People / Q000235:genetics*