Turning up a muscle switch makes muscles bigger
Overexpression of the vitamin D receptor (VDR) induces skeletal muscle hypertrophy
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists made a special muscle switch (VDR) work harder in rats and their muscles grew bigger. In people who lifted weights for 20 weeks, those whose muscles made more of this switch also gained more muscle mass — even if their vitamin D levels didn’t change.
Surprising Findings
VDR expression correlated with muscle growth in humans—but not with strength gains or blood vitamin D levels.
Everyone assumes more vitamin D = stronger muscles. This study shows muscle growth can happen independently of systemic vitamin D, and strength gains didn’t track with VDR levels—suggesting hypertrophy and strength are regulated differently.
Practical Takeaways
Focus on resistance training to naturally upregulate VDR in your muscles—don’t rely on vitamin D supplements alone for muscle growth.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists made a special muscle switch (VDR) work harder in rats and their muscles grew bigger. In people who lifted weights for 20 weeks, those whose muscles made more of this switch also gained more muscle mass — even if their vitamin D levels didn’t change.
Surprising Findings
VDR expression correlated with muscle growth in humans—but not with strength gains or blood vitamin D levels.
Everyone assumes more vitamin D = stronger muscles. This study shows muscle growth can happen independently of systemic vitamin D, and strength gains didn’t track with VDR levels—suggesting hypertrophy and strength are regulated differently.
Practical Takeaways
Focus on resistance training to naturally upregulate VDR in your muscles—don’t rely on vitamin D supplements alone for muscle growth.
Publication
Journal
Molecular Metabolism
Year
2020
Authors
J. Bass, Asif Nakhuda, C. Deane, M. Brook, D. Wilkinson, B. Phillips, A. Philp, J. Tarum, F. Kadi, D. Andersen, A. M. Garcia, Ken Smith, I. Gallagher, N. Szewczyk, M. Cleasby, P. Atherton
Related Content
Claims (6)
When scientists turned up the vitamin D receptor in the leg muscles of rats for 10 days, the muscle fibers got bigger, the muscles made more protein, and key growth signals kicked in—so it looks like boosting this receptor might help muscles grow.
When people do supervised weight training for 20 weeks, their muscles make more of a protein called VDR—and that’s linked to gaining more muscle mass, but not to getting stronger or having more vitamin D in their blood. So VDR might be a sign that muscle growth is happening, even if vitamin D levels don’t change.
In rats, having more of a protein called VDR seems to help muscle repair cells multiply and grow, while reducing a protein that stops muscle growth—so it might help rats build more muscle.
In rats, having more of a protein called VDR seems to turn on genes that help build stronger muscle scaffolding, which might help the muscles grow bigger and work better.
When people lift weights, their muscles seem to adjust how they use vitamin D internally, and that change matches up with how much of a certain enzyme they make in the muscle — but it doesn’t match up with how much vitamin D is floating in their blood. So maybe what’s happening inside the muscle matters more than what’s in the bloodstream.