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Muscle improved by increasing vitamin D if previously less than 24 ng – June 2013

Vitamin D and Muscle Function: Is There a Threshold in the Relation?

Journal of the American Medical Directors Association, Available online 27 June 2013
Hennie C.J.P. Janssen, MDa, hcjp.janssen at gmail.com , Marielle H. Emmelot-Vonk, MD, PhD a; Harald J.J. Verhaar, MD, PhD a; Yvonne T. van der Schouw, Profb
a Department of Geriatrics, University Medical Center Utrecht, Utrecht, The Netherlands
b Julius Center for Health Sciences and Primary Care, Utrecht University, Utrecht, The Netherlands

Objectives: First, to determine the association between serum 25 hydroxyvitamin D (25OHD) concentration and muscle mass, strength, and performance. Second, to explore if there is a threshold in the association.

Design: Cross-sectional, single-center study.

Setting: The central part of the Netherlands (52° Northern latitude).

Participants: A total of 802 independently living men and postmenopausal women 40 to 80 years of age.

Measurements: Health-related and lifestyle factors, including physical activity, 25OHD concentration, lean mass, handgrip strength, knee extension strength, and physical performance were determined.

Results: Overall, higher 25OHD level was significantly associated with higher lean mass (22.6 g per nmol/L, 95% CI 7.3–37.9), handgrip strength (0.020 kg per nmol/L, 95% CI 0.001–0.038), and physical performance (0.006 points per nmol/L, 95% CI 0.001–0.012), after adjustment for various confounders.
This association was most pronounced below a 25OHD level of 60 nmol/L, with lean mass increase 79.6 g per nmol/L (95% CI 40.8–118.4, P < .01), handgrip strength 0.09 kg per nmol/L (95% CI 0.045–0.141, P < .01), and physical performance 0.02 points per nmol/L (95% CI 0.005–0.032, P < .01), and these significant associations attenuated to null above this threshold.

Conclusion: In middle-aged men and (postmenopausal) women, a higher 25OHD level was significantly associated with higher lean mass, muscle strength, and performance. These associations were most pronounced below 60 nmol/L and absent above 60 nmol/L, indicating a ceiling effect.

See also VitaminDWiki