The Roles of Vitamin D in Skeletal Muscle: Form, Function, and Metabolism
Girgis CM, Clifton-Bligh RJ, Hamrick MW, Holick MF, Gunton JE
Published in Endocrine Reviews
Abstract
Comprehensive review examining mechanisms by which vitamin D influences muscle function, including effects on muscle fiber composition.
Methodology
Comprehensive review of vitamin D action in skeletal muscle spanning vitamin D receptor biology, animal models, observational studies and randomised supplementation trials.
Key Findings
Severe vitamin D deficiency causes proximal myopathy with type II (fast-twitch) fibre atrophy that improves with repletion. Observational data link low 25(OH)D with reduced strength and higher fall risk in older adults. Supplementation trials show benefit mainly in deficient and older populations, particularly for falls reduction; trials in replete adults and athletes show little or no strength gain. Direct genomic and non-genomic vitamin D receptor signalling in muscle is supported, though receptor expression in mature myocytes remains debated.
Conclusions
Vitamin D has a genuine role in muscle form and function, but clinically meaningful strength and falls benefits are concentrated in deficient and elderly populations rather than in already-replete individuals.
Limitations
Narrative review without pooled effect estimates or formal risk-of-bias appraisal; underlying trials are heterogeneous in dose, form and baseline status; mechanistic conclusions rely partly on animal and cell models with contested vitamin D receptor detection in muscle.
Supplements Studied
Severe vitamin D deficiency causes proximal myopathy with type II (fast-twitch) fibre atrophy that improves with repletion. Observational data link low 25(OH)D with reduced strength and higher fall risk in older adults. Supplementation trials show benefit mainly in deficient and older populations, particularly for falls reduction; trials in replete adults and athletes show little or no strength gain. Direct genomic and non-genomic vitamin D receptor signalling in muscle is supported, though rece
Outcomes Measured
Vitamin D influences muscle fiber composition and contractile function through vitamin D receptors in muscle tissue, supporting overall physical performance.
Related Health Concerns
Study Details
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