title: Adequate dietary protein is associated with better physical performance among post-menopausal women 60-90 years.
abstract: OBJECTIVE
  Sarcopenia, the involuntary loss of skeletal muscle with age, affects up to one-quarter of older adults. Evidence indicates a positive association between dietary protein intake and lean muscle mass and strength among older persons, but information on dietary protein's effect on physical performance in older adults has received less attention.
  
  
  METHODS
  Cross-sectional observational analysis of the relationship of dietary protein on body composition and physical performance.
  
  
  METHODS
  Clinical research center.
  
  
  METHODS
  387 healthy women aged 60 - 90 years (mean 72.7 ± 7.0 y).
  
  
  METHODS
  Measures included body composition (fat-free mass, appendicular skeletal mass and fat mass) via dual x-ray absorptiometry (DXA), physical performance (Physical Performance Test [PPT] and Short Physical Performance Battery [SPPB]), handgrip strength, Physical Activity Scale in the Elderly (PASE), quality of life measure (SF-8), falls, fractures, nutrient and macromolecule intake (four-day food record). Independent samples t-tests determined mean differences between the above or below RDA protein groups.
  
  
  METHODS
  Analysis of covariance was used to control for body mass index (BMI) between groups when assessing physical performance, physical activity and health-related quality of life.
  
  
  RESULTS
  The subjects consumed an average of 72.2 g protein/day representing 1.1 g protein/kg body weight/day. Subjects were categorized as below the recommended daily allowance (RDA) for protein (defined as less than 0.8 g protein/kg) or at or above the RDA (equal to or higher than 0.8 g protein/kg). Ninety-seven subjects (25%) were in the low protein group, and 290 (75%) were in the higher protein group. Women in the higher protein group had lower body mass, including fat and lean mass, and fat-to-lean ratio than those in the lower-protein group (p <0.001). Composite scores of upper and lower extremity strength were impaired in the group with low protein intake; SPPB score was 9.9±1.9 compared to 10.6±1.6 in those with higher protein intake and PPT was 19.8± 2.9 compared to 20.9± 2.1 in the low and higher protein groups, respectively. The results were attenuated by correction for BMI, but remained significant. The physical component of the SF-8 was also lower in the low protein group but did not remain significant when controlling for BMI. No significant differences were found in hand grip strength or reported physical activity.
  
  
  CONCLUSIONS
  Healthy, older postmenopausal women consumed, on average, 1.1 g/kg/d protein, although 25% consumed less than the RDA. Those in the low protein group had higher body fat and fat-to-lean ratio than those who consumed the higher protein diet. Upper and lower extremity function was impaired in those who consumed a low protein diet compared to those with a higher protein intake. Protein intake should be considered when evaluating the multi-factorial loss of physical function in older women.
authors: Anne Kenny, MD, Center on Aging, MC-5215, University of Connecticut Health Center, Farmington, CT 06030-5215, Email: kenny@uchc.edu, Phone: (860) 679-3956, Fax: (860) 679-1307.
authors: L
authors: L
authors: Gregorio
authors: J
authors: J
authors: Brindisi
authors: A
authors: A
authors: Kleppinger
authors: R
authors: R
authors: Sullivan
authors: K M
authors: KM
authors: Mangano
authors: J D
authors: JD
authors: Bihuniak
authors: A M
authors: AM
authors: Kenny
authors: J E
authors: JE
authors: Kerstetter
authors: K L
authors: KL
authors: Insogna
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D018737:Hand Strength; D064368:Healthy Volunteers; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D009043:Motor Activity; D018482:Muscle, Skeletal / Q000378:metabolism; D017698:Postmenopause; D011788:Quality of Life; D011795:Surveys and Questionnaires
chemical_list: D004044:Dietary Proteins