title: Vitamin D status is associated with functional limitations and functional decline in older individuals.
abstract: BACKGROUND
  Vitamin D is known to influence muscle health. A reduction in muscle mass increases the risk of functional limitations among older individuals.
  
  
  OBJECTIVE
  The aim of this study was to examine the relationship between vitamin D status and functional limitations.
  
  
  METHODS
  Two independent cohorts of the Longitudinal Aging Study Amsterdam were used. Participants were aged 65 to 88 years (older cohort, n = 1237; baseline 1995) and 55 to 65 years (younger cohort, n = 725; baseline 2002).
  
  
  METHODS
  Questions on the ability and degree of difficulty to perform 6 functions of daily life were asked.
  
  
  RESULTS
  Of the participants, 56% in the older cohort and 30% in the younger cohort had ≥1 limitation. Vitamin D deficiency (25-hydroxyvitamin D level of <20 ng/mL) compared with the value in the reference group (>30 ng/mL) was related to the presence of functional limitations at baseline (odds ratio [OR] = 1.7; 95% confidence interval [CI], 1.2-2.5 and OR = 2.2; 95% CI 1.3-3.7 for the older and younger cohorts, respectively). In the older cohort, vitamin D deficiency was associated with an increase in limitations at 3 years (OR = 2.0; 95% CI, 1.1-3.5), whereas vitamin D deficiency in the younger cohort was associated with an increase in limitations at 6 years (OR = 3.3; 95% CI, 1.1-10.1). Analyses were adjusted for confounders.
  
  
  CONCLUSIONS
  Vitamin D status is associated with functional limitations cross-sectionally and longitudinally in individuals aged 55 to 65 years and those 65 years and older. The possible association of vitamin D with functional limitations is present after a shorter follow-up time in the oldest age group compared with the younger age group.
authors.affiliation: Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, 1081 BT Amsterdam, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Sohl
authors.forename: N M
authors.initials: NM
authors.lastname: van Schoor
authors.forename: R T
authors.initials: RT
authors.lastname: de Jongh
authors.forename: M
authors.initials: M
authors.lastname: Visser
authors.forename: D J H
authors.initials: DJ
authors.lastname: Deeg
authors.forename: P
authors.initials: P
authors.lastname: Lips
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000375:Aging / Q000097:blood / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000503:physiopathology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D