A Randomized Controlled Trial of the Effects of Vitamin D on Muscle Strength and Mobility in Older Women with Vitamin D Insufficiency

Kun Zhu, PhD; Nicole Austin, PhD; Amanda Devine, PhD; David Bruce, MD; Richard L. Prince, MD

J Am Geriatr Soc. 2010;58(11):2063-2068.

Conclusion

In conclusion, vitamin D supplementation in older individuals receiving calcium improved hip muscle strength and mobility in participants with low baseline values. Given the importance of maintaining physical performance in older people to maintain a healthy and independent life in the community, vitamin D should be added to those with insufficiency or deficiency to improve muscle function.

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Acknowledgments
We are grateful to all the study participants for their cooperation. The Boots Company of Australia supplied the vitamin D preparation (Ostelin) and identical placebo free of charge. Mission Pharmaceutical supplied the calcium citrate free of charge.

Conflict of Interest
The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper.

The study was supported by a research grant from the National Health and Medical Research Council of Australia (Project Grant 353638).

Author Contributions
KZ performed data analysis and drafted the manuscript. NA was involved in the data collection. AD and DB were involved in the conception and design of the study. RLP was involved in the conception, design and interpretation of the study. All authors contributed to the writing of the manuscript.

Sponsor's Role
None of the funding agencies had any role in the conduct of the study; collection, management, analysis, or interpretation of the data; or preparation, review, or approval of the manuscript. Kun Zhu, Nicole Austin, Amanda Devine, David Bruce, and Richard Prince had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Cite this: A Randomized Controlled Trial of the Effects of Vitamin D on Muscle Strength and Mobility in Older Women with Vitamin D Insufficiency - Medscape - Nov 01, 2010.

Table 1. Subject Characteristics at Baseline
Characteristic	Vitamin D+Calcium (n=129)	Placebo+Calcium (n=132)
Age, mean ± SD	76.8 ± 4.2	77.0 ± 4.8
Weight, kg, mean ± SD	73.7 ± 14.2	71.8 ± 12.8
Height, cm, mean ± SD	158.0 ± 6.4	159.5 ± 6.0
Body mass index, kg/m², mean ± SD	29.5 ± 5.4	28.2 ± 4.9
Dietary calcium intake, mg/d, mean ± SD	1085 ± 500	1088 ± 411
Physical activity, kcal/d, median (interquartile range)^*	61 (10, 194)	53 (17, 139)
Mini-Mental State Examination score, mean ± SD	28.6 ± 1.4	28.4 ± 1.6
Ethnicity, %
Caucasian	96.1	97.0
Asian	3.1	3.0
Other	0.8	0
Fitness self-rating, %
Unfit	9.6	6.3
Below average fitness for age	9.6	8.6
Average fitness for age	60.8	66.4
Above fitness for age	15.2	17.2
Very fit	4.8	1.6
Using walking aid, %	17.1	15.9

^* There were no significant differences between the two groups in baseline characteristics in the table (Student t-test or Mann-Whitney test).
SD=standard deviation.

Table 2. Vitamin D Status, Mobility, and Muscle Strength at Baseline and 1 Year
Factor	Mean ± Standard Deviation
	Vitamin D+Calcium (n=129)		Placebo+Calcium (n=132)
	Baseline	1 year	Baseline	1 year
Serum 25-hydroxyvitamin D, ng/mL	18.1 ± 5.0	24.0 ± 5.6^*	17.7 ± 5.2	18.0 ± 5.4
Timed Up and Go Test, seconds	11.0 ± 5.3	8.1 ± 3.9^*	10.8 ± 4.6	9.0 ± 7.0^*
Lower limb muscle strength, kg
Ankle dorsiflexion	11.6 ± 4.4	10.9 ± 3.7^*	11.8 ± 4.2	10.9 ± 4.0^*
Knee flexor	11.8 ± 3.6	12.9 ± 3.5^*	11.9 ± 3.7	13.0 ± 3.9^*
Knee extensor	18.3 ± 6.4	18.0 ± 5.0	18.8 ± 7.3	18.3 ± 5.5
Hip extensor	14.6 ± 5.7	17.2 ± 5.2^*	14.4 ± 5.3	16.9 ± 6.2^*
Hip abductor	12.3 ± 4.2	14.5 ± 4.1^*	12.2 ± 5.0	14.1 ± 4.9^*
Hip flexor	14.5 ± 5.0	15.4 ± 4.2^*	14.5 ± 5.7	15.4 ± 4.8^*
Hip adductor	14.4 ± 4.7	16.4 ± 4.4^*	14.7 ± 5.0	16.3 ± 5.2^*

^* Significantly different from baseline, P<.05.

Table 3. Change in Hip Extensor and Adductor Strength According to Baseline Tertile Values
Tertile of Strength (kg)	Mean (Standard Error)
	Absolute Change (kg)		% Difference in Change (Vitamin D–Placebo)
	Vitamin D	Placebo	% Difference in Change (Vitamin D–Placebo)
Hip extensor
Lowest (≤11)	5.2 (0.7)	3.1 (0.8)	22.6 (9.5)^*
Middle (12–15)	3.5 (0.6)	4.3 (0.7)	−3.8 (5.9)
Highest (≥16)	0.1 (0.7)	0.7 (0.8)	−1.1 (5.1)
Hip adductor
Lowest (≤12)	3.4 (0.5)	2.1 (0.6)	13.5 (6.7)^*
Middle (13–16)	2.2 (0.5)	3.2 (0.5)	−6.8 (4.5)
Highest (≥17)	−0.4 (0.6)	−0.3 (0.6)	−0.2 (4.2)

^* The increase in strength was significantly greater in the vitamin D group than in the placebo group in the same tertile, P<.05.

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