Context: Vitamin D deficiency is prevalent worldwide. Vitamin D supplementation has shown variable effect on skeletal muscle strength in the elderly with hypovitaminosis D. There is a paucity of similar data in young individuals.
Objective: To study the effect of cholecalciferol and calcium supplementation on muscle strength and energy metabolism in young individuals.
Subjects: Forty healthy volunteers (24 M/16 F, mean age (SD) 31.5 ± 5.0 year) with hypovitaminosis D were randomized to either oral cholecalciferol (60,000 IU D3/week for 8 weeks followed by 60,000 IU/month for 4 months) with 1 g of elemental calcium daily or dual placebos for 6 months.
Measurements: Handgrip and gastro-soleus dynamometry, pinch-grip strength, respiratory pressures, 6-min walk-test and muscle energy metabolism on (31) P magnetic resonance spectroscopy were assessed at baseline and after 6 months.
Results: The mean serum 25(OH)D in the supplemented and placebo groups at baseline, two and 6 months were 25.4 ± 9.9, 94.5 ± 53.8 and 56.0 ± 17.0 nm, and 21.1 ± 9.4, 32.8 ± 14.4 and 29.7 ± 15.0 nm, respectively. The supplemented group gained a handgrip strength of 2.4 kg (95% C.I. = 1.2-3.6); gastro-soleus strength of 3.0 Nm (95% C.I. = 0.1-5.9) and walking distance of 15.9 m (95% C.I. = 6.3-25.5) over the placebo group after adjustment for age, gender and respective baseline parameters. Muscle energy parameters were comparable at 6 months.
Conclusions: Six months of cholecalciferol and calcium supplementation results in enhanced skeletal muscle strength and physical performance despite no change in muscle energy parameters. Cholecalciferol supplementation of 60,000 IU per month could not maintain 25(OH)D levels in the sufficient range.
Trial registration: ClinicalTrials.gov NCT00682214.
© 2010 Blackwell Publishing Ltd.