title: High protein intake is associated with low prevalence of frailty among old Japanese women: a multicenter cross-sectional study.
abstract: BACKGROUND
  Protein intake has been inversely associated with frailty. However, no study has examined the effect of the difference of protein sources (animal or plant) or the amino acid composing the protein on frailty. Therefore, we examined the association of protein and amino acid intakes with frailty among elderly Japanese women.
  
  
  METHODS
  A total of 2108 grandmothers or acquaintances of dietetic students aged 65 years and older participated in this cross-sectional multicenter study, which was conducted in 85 dietetic schools in 35 prefectures of Japan. Intakes of total, animal, and plant protein and eight selected amino acids were estimated from a validated brief-type self-administered diet history questionnaire and amino acid composition database. Frailty was defined as the presence of three or more of the following four components: slowness and weakness (two points), exhaustion, low physical activity, and unintentional weight loss.
  
  
  RESULTS
  The number of subjects with frailty was 481 (23%). Adjusted ORs (95% CI) for frailty in the first, second, third, fourth, and fifth quintiles of total protein intake were 1.00 (reference), 1.02 (0.72, 1.45), 0.64 (0.45, 0.93), 0.62 (0.43, 0.90), and 0.66 (0.46, 0.96), respectively (P for trend = 0.001). Subjects categorized to the third, fourth, and fifth quintiles of total protein intake (>69.8 g/d) showed significantly lower ORs than those to the first quintile (all P <0.03). The intakes of animal and plant protein and all selected amino acids were also inversely associated with frailty (P for trend <0.04), with the multivariate adjusted OR in the highest compared to the lowest quintile of 0.73 for animal protein and 0.66 for plant protein, and 0.67-0.74 for amino acids, albeit that the ORs for these dietary variables were less marked than those for total protein.
  
  
  CONCLUSIONS
  Total protein intake was significantly inversely associated with frailty in elderly Japanese women. The association of total protein with frailty may be observed regardless of the source of protein and the amino acid composing the protein.
authors.forename: Satomi
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Keiko
authors.initials: K
authors.lastname: Asakura
authors.forename: Hitomi
authors.initials: H
authors.lastname: Suga
authors.affiliation: Department of Social and Preventive Epidemiology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan. stssasak@m.u-tokyo.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sasaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000596:Amino Acids / Q000008:administration & dosage / Q000032:analysis; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D030562:Databases, Protein; D018753:Diet, Protein-Restricted / Q000009:adverse effects; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000737:chemistry / Q000627:therapeutic use; D005260:Female; D016330:Frail Elderly; D006306:Health Surveys; D006801:Humans; D007564:Japan / Q000453:epidemiology; D053609:Lethargy / Q000209:etiology / Q000517:prevention & control; D018908:Muscle Weakness / Q000209:etiology / Q000517:prevention & control; D010940:Plant Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use; D015995:Prevalence; D055948:Sarcopenia / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D057185:Sedentary Behavior; D015431:Weight Loss
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D010940:Plant Proteins