A randomized controlled trial of the effects of vitamin D on muscle strength and mobility in older women with vitamin D insufficiency.
OBJECTIVE
To evaluate the effects of vitamin D treatment on muscle strength and mobility in older women with vitamin D insufficiency.


METHODS
One-year population-based, double-blind, randomized, controlled trial.


METHODS
Perth, Australia (latitude 32°S).


METHODS
Three hundred two community-dwelling ambulant elderly women aged 70 to 90 with a serum 25-hydroxyvitamin D (25(OH)D) concentration less than 24 ng/mL.


METHODS
Vitamin D(2) 1,000 IU/d or identical placebo; calcium citrate (1 g calcium/d) in both groups.


METHODS
Lower limb muscle strength and mobility as assessed using the Timed Up and Go Test (TUAG).


RESULTS
At baseline, mean ± standard deviation serum 25(OH)D was 17.7 ± 4.2 ng/mL; this increased to 24.0 ± 5.6 ng/mL in the vitamin D group after 1 year but remained the same in the placebo group. For hip extensor and adductor strength and TUAG, but not for other muscle groups, a significant interaction between treatment group and baseline values was noted. In those with baseline values in the lowest tertile, vitamin D improved muscle strength and TUAG more than calcium alone (mean (standard error): hip extensors 22.6% (9.5%); hip adductors 13.5% (6.7%), TUAG 17.5% (7.6%), P < .05). Baseline 25(OH)D levels did not influence patient response to supplementation.


CONCLUSIONS
Vitamin D therapy was observed to increase muscle function in those who were the weakest and slowest at baseline. Vitamin D should be given to people with insufficiency or deficiency to improve muscle strength and mobility.
School of Medicine and Pharmacology, University of Western Australia, Perth, Australia. kzhu@meddent.uwa.edu.au
Kun
K
Zhu
Nicole
N
Austin
Amanda
A
Devine
David
D
Bruce
Richard L
RL
Prince
D000368:Aged; D000369:Aged, 80 and over; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D051346:Mobility Limitation; D053580:Muscle Strength / Q000187:drug effects*; D014807:Vitamin D / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000188:drug therapy* / Q000503:physiopathology*; D014815:Vitamins / Q000627:therapeutic use*
D014815:Vitamins; D014807:Vitamin D