VITAMIN D-RELATED CHANGES IN PHYSICAL PERFORMANCE: A SYSTEMATIC REVIEW

Objective: The objective of this study was to systematically review all the published articles examining the effects of low serum vitamin D concentration and vitamin D supplementation on muscle, balance and gait performance among people aged 65 and older. Methods: An English and French Medline search ranging from January 2004 to November 2008 indexed under the Medical Subject Heading (MeSH) terms "aged OR aged, 80 and over" AND "Vitamin D OR Vitamin D Deficiency" combined with the terms "Gait" OR "Gait Apraxia" OR "Gait Disorders, Neurologic" OR "Walking" OR "Mobility Limitation" OR "Polyneuropathy" OR "Proprioception" OR "Ataxia" OR "Accidental Falls" was performed. Results: Of the 102 selected studies, 16 met the selection criteria and were included in the final analysis. There were 8 observational studies and 8 interventional studies. The number of participants ranged from 24 to 33067. A majority of studies examined community-dwelling older women. Five observational studies showed a significant positive association, whereas three studies did not. Four of the 5 studies and two of the 3 studies which tested the vitamin D supplementation effect, respectively on balance and gait, showed no significant effect. Four studies showed a significant effect on muscle strength, while this effect was not observed in three others studies. In addition, there was no significant association between vitamin D supplementation and an improvement of the sit-to-stand test results in 50% of the studies. Conclusions: The findings show that the association between vitamin D and physical performance remains controversial. Observational studies and clinical trials yielded divergent results, which highlights the complex and to date still poorly understood association between serum vitamin D concentration or vitamin D supplementation and physical performance.