title: Sex-specific association of serum vitamin D levels with physical function in older adults.
abstract: In women, but not men, lower 25-hydroxyvitamin D [25(OH)D] levels were associated with impaired performance on two lower extremity function tests in both cross-sectional and prospective analyses.
  
  
  BACKGROUND
  Preserved physical function may explain how 25(OH)D supplementation reduces falls and fractures.
  
  
  METHODS
  A total of 1,065 community-dwelling men and women (mean age 74.6 years) with 25(OH)D levels and performance on timed up and go (TUG) and timed chair stand (TCS) were seen in 1997-1999; 769 (72%) participants returned for follow-up. Associations were examined using generalized linear models.
  
  
  RESULTS
  25(OH)D levels were higher in men than women, but the prevalence of vitamin D insufficiency defined as 25(OH)D <75 nmol/L was 14%. There were no baseline sex differences in TUG or TCS. However, after 2.5 years, decline in TCS and TUG was greater in women than men (11% vs. 3%; p < 0.001). Women in the lowest 25(OH)D quartile (<80 nmol/L) compared to the highest quartile had an accelerated rate of functional decline on the TUG and TCS independent of covariates. No significant associations were seen in men.
  
  
  CONCLUSIONS
  In women, but not men, lower 25(OH)D levels were associated with impaired performance on two lower extremity function tests in both cross-sectional and prospective analyses. These results provide additional evidence that 25(OH)D is associated with physical function, which may explain how vitamin D supplementation reduces falls and fractures.
authors.affiliation: Division of Hospital Medicine, Department of Medicine, University of California, San Diego, La Jolla, San Diego, CA 92093-0659, USA. tldam@ucsd.edu
authors.forename: T-T L
authors.initials: TT
authors.lastname: Dam
authors.forename: D
authors.initials: D
authors.lastname: von Mühlen
authors.forename: E L
authors.initials: EL
authors.lastname: Barrett-Connor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002140:California; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D057187:Independent Living; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D018482:Muscle, Skeletal / Q000502:physiology*; D011446:Prospective Studies; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D