title: Protein Intake and Mobility Limitation in Community-Dwelling Older Adults: the Health ABC Study.
abstract: OBJECTIVE
  The current Recommended Dietary Allowance (RDA) for protein is based on short-term nitrogen balance studies in young adults and may underestimate the amount needed to optimally preserve physical function in older adults. We examined the association between protein intake and the onset of mobility limitation over 6 years of follow-up in older adults in the Health ABC study.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Memphis, Tennessee and Pittsburgh, Pennsylvania.
  
  
  METHODS
  Community-dwelling, initially well-functioning adults aged 70-79 years (n = 1998).
  
  
  METHODS
  Protein intake (g/kg body weight/d) was calculated using an interviewer-administered 108-item food frequency questionnaire at baseline. Mobility limitation was assessed semi-annually and defined as reporting any difficulty walking one-quarter of a mile or climbing 10 steps on 2 consecutive 6-month contacts. The association between protein intake and incident mobility limitation was examined using Cox proportional hazard regression models adjusting for demographics, behavioral characteristics, chronic conditions, total energy intake, and height.
  
  
  RESULTS
  Mean (SD) protein intake was 0.91 (0.38) g/kg body weight/d, with 43% reporting intakes less than the RDA (0.8 g/kg body weight/d). During 6 years of follow-up, 705 participants (35.3%) developed mobility limitations. Compared to participants in the upper tertile of protein intake (≥1.0 g/kg body weight/d), participants in the lower two tertiles of protein intake (<0.7 and 0.7 -<1.0 g/kg body weight/d) were at greater risk of developing mobility limitation over 6 years of follow-up (RR (95% CI): 1.86 (1.41-2.44) and 1.49 (1.20-1.84), respectively).
  
  
  CONCLUSIONS
  Lower protein intake was associated with increased risk of mobility limitation in community-dwelling, initially well-functioning older adults. These results suggest that protein intakes of ≥1.0 g/kg body weight/d may be optimal for maintaining physical function in older adults.
authors.affiliation: Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Denise K
authors.initials: DK
authors.lastname: Houston
authors.affiliation: Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Janet A
authors.initials: JA
authors.lastname: Tooze
authors.affiliation: Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Katelyn
authors.initials: K
authors.lastname: Garcia
authors.affiliation: Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Visser
authors.affiliation: University of California, San Francisco, California.
authors.forename: Susan
authors.initials: S
authors.lastname: Rubin
authors.affiliation: National Institute on Aging, Bethesda, Maryland.
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.affiliation: University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.affiliation: Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
mesh_terms: D000368:Aged; D000375:Aging; D000596:Amino Acids; D001835:Body Weight / Q000502:physiology; D004435:Eating; D005006:Ethnicity; D005260:Female; D006801:Humans; D057187:Independent Living; D008297:Male; D051346:Mobility Limitation; D010414:Pennsylvania; D011446:Prospective Studies; D064167:Recommended Dietary Allowances; D011795:Surveys and Questionnaires; D013714:Tennessee
chemical_list: D000596:Amino Acids
keywords: aging; mobility limitation; protein