title: Physical Activity Modifies the Association between Dietary Protein and Lean Mass of Postmenopausal Women.
abstract: Maintenance of lean muscle mass and related strength is associated with lower risk for numerous chronic diseases of aging in women.
  
  
  
  Our aim was to evaluate whether the association between dietary protein and lean mass differs by physical activity level, amino acid composition, and body mass index categories.
  
  
  
  We performed a cross-sectional analysis of a prospective cohort.
  
  
  
  Participants were postmenopausal women from the Women's Health Initiative with body composition measurements by dual-energy x-ray absorptiometry (n=8,298).
  
  
  
  Our study measured percent lean mass, percent fat mass, and lean body mass index.
  
  
  
  Linear regression models adjusted for scanner serial number, age, calibrated energy intake, race/ethnicity, neighborhood socioeconomic status, and recreational physical activity were used to determine the relationship between protein intake and body composition measures. Likelihood ratio tests and stratified analysis were used to investigate physical activity and body mass index as potential effect modifiers.
  
  
  
  Biomarker-calibrated protein intake was positively associated with percent lean mass; women in the highest protein quintile had 6.3 percentage points higher lean mass than the lowest quintile (P<0.001). This difference rose to 8.5 percentage points for physically active women in the highest protein quintile (Pinteraction=0.023). Percent fat mass and lean body mass index were both inversely related to protein intake (both P<0.001). Physical activity further reduced percent fat mass (Pinteraction=0.022) and lean body mass index (Pinteraction=0.011). Leucine intake was associated with lean mass, as were branched chain amino acids combined (both P<0.001), but not independent of total protein. All associations were observed for normal-weight, overweight, and obese women.
  
  
  
  Protein consumption up to 2.02 g/kg body weight daily is positively associated with lean mass in postmenopausal women. Importantly, those that also engage in physical activity have the highest lean mass across body mass index categories.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Martinez
authors.forename: Betsy C
authors.initials: BC
authors.lastname: Wertheim
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Thomson
authors.forename: Jennifer W
authors.initials: JW
authors.lastname: Bea
authors.forename: Robert
authors.initials: R
authors.lastname: Wallace
authors.forename: Matthew
authors.initials: M
authors.lastname: Allison
authors.forename: Linda
authors.initials: L
authors.lastname: Snetselaar
authors.forename: Zhao
authors.initials: Z
authors.lastname: Chen
authors.forename: Rami
authors.initials: R
authors.lastname: Nassir
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Thompson
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D003430:Cross-Sectional Studies; D004044:Dietary Proteins / Q000008:administration & dosage*; D002149:Energy Intake; D015444:Exercise; D005260:Female; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D015596:Nutrition Assessment; D017698:Postmenopause; D011446:Prospective Studies
chemical_list: D004044:Dietary Proteins
keywords: Dietary protein; Fat mass; Lean mass; Leucine; Physical activity