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How Optimizing Your Vitamin D Status Promotes Muscle Health & Function*

Morgan Chamberlain
Author: Expert reviewer:
May 7, 2022
Morgan Chamberlain
mbg Supplement Editor
By Morgan Chamberlain
mbg Supplement Editor
Morgan Chamberlain is a supplement editor at mindbodygreen. She graduated from Syracuse University with a Bachelor of Science degree in magazine journalism and a minor in nutrition.
Ashley Jordan Ferira, Ph.D., RDN
Expert review by
Ashley Jordan Ferira, Ph.D., RDN
mbg Vice President of Scientific Affairs
Ashley Jordan Ferira, Ph.D., RDN is Vice President of Scientific Affairs at mindbodygreen. She received her bachelor's degree in Biological Basis of Behavior from the University of Pennsylvania and Ph.D. in Foods and Nutrition from the University of Georgia.
Image by Jovo Jovanovic / Stocksy
May 7, 2022
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In ancient Greece, rooms with prime sun exposure were recommended to strengthen muscles, and Olympians were told to train outside in the sunshine for optimal performance. No, they weren't just trying to look tan in their togas—as it turns out, the Greeks recognized the vitamin D/muscle connection long before the science was well understood. 

Though vitamin D's contributions to bone health are far more researched, the sunshine vitamin's involvement in muscle health is just as important. Evidence suggests that vitamin D plays a vital role1 in many skeletal muscle activities—including early development, mass, function, and metabolism.* 

Vitamin D health benefits.

Vitamin D receptors (VDR) have been found in skeletal muscle (aka the muscles on your bones that help you move), suggesting vitamin D plays a crucial role in the maintenance of muscle form and function.*

If you think vitamin D isn't a top priority for your own musculoskeletal health because you aren't a pro athlete, think again: Skeletal muscle accounts for approximately 35% of total body mass in females and 42% in males, making it an important factor in overall body composition, metabolism, and physical function. Sufficient vitamin D levels are a must for healthy muscles, no matter how you're using them.*

Support muscle function.

According to nutrition musculoskeletal scientist Christian Wright, Ph.D., vitamin D modulates a number of cellular pathways and functions that maintain muscle health—such as skeletal muscle differentiation (i.e., dividing cells decide to become muscle cells!), growth, and even regeneration.* "Having adequate levels of vitamin D is essential for optimizing the benefits of vitamin D on muscle,"* says Wright. (More on vitamin D levels here.)

The research supports his insight, demonstrating vitamin D's ability to improve muscle function when given to those deficient in vitamin D (i.e., correct the deficiency).* With vitamin D deficiency and insufficiency affecting 29% and 41% of U.S. adults2, respectively, a significant portion of the U.S. population can benefit from the muscle health benefits that healthy levels of vitamin D support.* 

Beyond its direct impact on muscle health, vitamin D also helps maintain calcium homeostasis.* This vitamin-mineral partnership is crucial to muscle contraction—i.e., the tightening, shortening, or lengthening of muscles to accomplish a physical activity.

That means hitting the gym (or this dance break workout we're loving) isn't the only critical way to benefit from muscle health support—vitamin D is helping you with everything from making your morning coffee to running to catching the train on your evening commute to the workout of your choice.* 

Maintain healthy muscle mass & overall body composition.

The total amount of skeletal, cardiac, and smooth muscles in your body make up your muscle mass, and sufficient vitamin D throughout life is required to maintain a healthy percentage.*

Higher muscle mass is related to a number of health benefits—including slowing down muscle loss with age, improving metabolism, and even longevity.* Indeed, older adults with more muscle mass were found to live longer than those with less in a 2014 clinical study3 published in the American Journal of Medicine.

Maintaining healthy muscle mass isn't as easy as adding some vitamin D to your diet (which rarely provides enough of the essential fat-soluble vitamin to affect your vitamin D status and health in a meaningful way). While a vitamin D supplement is a no-brainer for achieving and maintaining vitamin D sufficiency throughout life, your muscle mass will also benefit from an overall nutrient-dense dietary pattern (with a particular focus on high-quality and adequate protein) and regular physical activity, too.*

Additionally, there are many facets of body composition (the percentage of fat, bone, and yes, muscle) unique to each individual that affects the amount of vitamin D needed

Nutrition scientist and vice president of scientific affairs at mbg Ashley Jordan Ferira, Ph.D., RDN, previously shared that, "Adiposity, or the amount of body fat one has, is one key facet of body composition (as are lean mass and bone density). Research has repeatedly demonstrated that fat tissue is inversely correlated with vitamin D status (i.e., higher adiposity, lower vitamin D levels)."

The reasons for this are varied and "involve perturbations in storage, dilution, and complex feedback loops," explains Ferira. She goes on to say, "One major factor is that fat tissue has a tendency to store fat-soluble compounds like vitamin D, making less of this essential nutrient available to circulate and be activated to support our cells, tissues, and organs throughout the body."*

Additionally, according to Wright, there appears to be little to no additional benefit of vitamin D on muscle mass once sufficiency status is achieved. "Overall, vitamin D does not help increase muscle mass if circulating levels of 25-hydroxyvitamin D are at or above recommendations," says Wright. But as Ferira jokes, "That would be an excellent problem to have since 93%-plus of Americans aren't even eating their way to 400 IU of vitamin D3 a day."

What does this mean for us? Well, evidence suggests that muscle mass is greatly improved by vitamin D supplementation for those deficient or insufficient in the essential vitamin (again, 29% and 41% of American adults2, respectively), so a significant number of the U.S. population can benefit from adding some vitamin D to their supplement routine.* 

Of course, managing to squeak just above the cutoff for vitamin D insufficiency (30 ng/ml) is not the goal to aim for but a boundary to avoid. (More on vitamin D levels to achieve for lifelong health here.)

Aid skeletal muscle metabolism.

Wait, hold up—what is skeletal muscle metabolism, exactly? Well, it's a highly coordinated process involving communication between immune and muscle cells.

Skeletal muscle metabolism largely depends on mitochondrial oxidative capacity, and, according to Wright, vitamin D has been shown to influence factors of energy metabolism such as mitochondrial density and function.*

Increasing the size and number of your mitochondria, aka the powerhouse of the cell (thanks, high school biology class), helps the mitochondria convert energy (aka from the foods we eat throughout the day) into ATP, which is the primary carrier of energy in cells for all of their reactions and hard work. This process, called mitochondrial biogenesis, allows your muscles to work harder for longer.

Wright explains, "Increasing vitamin D concentrations is shown to increase mitochondrial biogenesis, oxygen consumption, and phosphate uptake, all the while decreasing oxidative stress."* In other words, vitamin D aids metabolic activities in skeletal muscle and supports the overall health of muscle cells, making it a powerful teammate for us and our daily movement and overall health.*

The takeaway.

Vitamin D is a critical nutritional player in our muscle health, not only when we exercise but for daily physical activity and functions as well.* The widespread prevalence of vitamin D nutritional inadequacy in the United States makes the vitamin D and muscle connection a vital topic of discovery, and while the research is ongoing, it's clear that sufficient vitamin D levels contribute to musculoskeletal health and function.* 

Because it's practically impossible to restore vitamin D levels from food and sunshine alone, vitamin D supplementation is also an important consideration when trying to achieve optimal muscle health.*

We rounded up the best high quality, research backed vitamin D supplements here, but for our top pick, look no further than, mindbodygreen's own vitamin D3 potency+. In addition to providing an effective level of vitamin D3 (5,000 IU) from sustainable organic algae, our vitamin D is optimized with built-in absorption technology to support your muscle, bone, immune, and whole-body health.*

Whether you're training for the Olympics, trying to master a yoga inversion, or simply looking to support day-to-day activities, consider (expert vetted and recommended) vitamin D supplementation—your muscles will thank you!*

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
Morgan Chamberlain author page.
Morgan Chamberlain
mbg Supplement Editor

Morgan Chamberlain is a supplement editor at mindbodygreen. She graduated from Syracuse University with a Bachelor of Science degree in magazine journalism and a minor in nutrition. Chamberlain believes in taking small steps to improve your well-being—whether that means eating more plant-based foods, checking in with a therapist weekly, or spending quality time with your closest friends. When she isn’t typing away furiously at her keyboard, you can find her cooking in the kitchen, hanging outside, or doing a vinyasa flow.