Takeaway
- In individuals with vitamin D insufficiency, four-month administration of vitamin D showed no effects on muscular strength.
Why this matters
- Findings warrant future studies including daily dosing, assessment of conutrient status and physical activity, and use of active vitamin D to understand the vitamin D metabolism and musculoskeletal health.
Study design
- 411 participants (men and women; age, 40–80 years) were randomly assigned to receive a loading dose of 100000 IU (2500 ug) vitamin D3 followed by 20000 IU (500 ug)/week (n=208) or placebo (n=203).
- Muscle strength was assessed by dynamometers at baseline and after 4 months.
- Funding: The North Norway Regional Health Authorities.
Key results
- Serum vitamin D increased by 56.2 ± 22.2 nmol/L in the vitamin D group and reduced by 4.5±12.8 nmol/L in the placebo group (P<.01).
- No significant difference was observed between both the group in terms of changes in muscle strength including:
- hip flexion (P=.64),
- biceps flexion (P=.43),
- pectorals (P=.43), and
- handgrip strength (P=.31).
- Changes in muscle strength did not differ between vitamin D and placebo group in the analyses stratified on gender (men and women), 25(OH)D levels (>/<25 nmol/L), smoking status (smokers or non-smokers), and BMI (>/< 27 kg/m2).
Limitations
- Duration of vitamin D supplementation was small.
- Study measured only aspect of muscular function.
References
References