By Jessica Monge, Health & Wellness Writer
Scientifically reviewed by: Michael A. Smith, MD
Vitamin D is famous for its many health benefits. Indeed, the “sunshine vitamin” (called so because it is manufactured in the body in response to sunlight) supports several biological processes, from bone health to cognitive function, to heart health and immune health. What may be surprising is that vitamin D is also necessary for muscle strength, especially as we age.
Researchers in Brazil and the UK found that adults 50 years of age and older with insufficient D levels or an outright vitamin D deficiency had a 78 percent increased risk of muscle strength loss. Does this mean adequate vitamin D levels can be the difference between enjoying those golden years with vitality and independence or with weak muscles and sarcopenia (defined as age-related loss of skeletal muscles, aka the muscles in our body we can move voluntarily, like your arms, legs and core)?
According to the new study published in Calcified Tissue International, a peer-reviewed medical journal, the answer is probably yes. “There is evidence that bone and muscle tissue are interconnected not only mechanically and physically but also biochemically via paracrine and endocrine communication. Thus, endocrine disorders, such as serum [vitamin D] insufficiency and deficiency, could provoke an imbalance in protein synthesis that would culminate in the loss of bone mineral density as well as a reduction in muscle mass, strength and function,” the authors explained.
Vitamin D and muscle strength
The researchers analyzed data from 3,205 participants who did not have any age-related muscle loss when they enrolled in the study. Participants had their blood serum D levels measured at baseline and again after four years. Grip strength was also measured at baseline—and after four years—as a reference to overall muscle strength and muscle function.
The results showed that age-related muscle loss and sarcopenia incidence was 70 percent higher in those with low vitamin D levels or a vitamin D deficiency. The researchers defined blood serum levels as:
- Sufficient: above 20 ng/mL
- Insufficient: below 20 ng/mL
- Deficient: below 12 ng/mL
The incidence of muscle loss was even greater—increasing by 78 percent—when the researchers removed data from participants with osteoporosis and those who were taking vitamin D . Important caveat: this recent study shows an association between skeletal muscle health and muscle strength and insufficient or deficient vitamin D levels—not necessarily a causation.
What does vitamin D do in the body?
Vitamin D behaves like a hormone; every cell in your body has a vitamin D receptor, and muscle cells are no exception). It regulates several biological pathways throughout the body, including:
- Bone health—Vitamin D is necessary for maintaining healthy bone density because it helps facilitate the absorption of calcium, essential for building the bone matrix. Low vitamin D levels have been associated with bone mineral loss and osteoporosis.
- Heart health—Vitamin D is vital for a healthy inflammatory response, protecting the delicate inner lining of blood vessels and arteries. Healthy serum D levels are also associated with healthy blood pressure.
- Skeletal muscle strength—As this and other studies show, sufficient D levels help maintain healthy skeletal muscle cells, muscle strength, muscle mass and muscle function. Vitamin D is necessary for muscle damage repair and muscle regeneration, which impact physical performance.
- Immune health—Vitamin D has a crucial role in immune health, too. It’s no surprise that vitamin D deficiency is prevalent in many autoimmune diseases. (Of course, vitamin D isn’t the only vitamin that supports your immune system; indeed, vitamin D and vitamin C together are a powerful combo for immune support.)
- Brain health—Studies show adequate vitamin D levels support cognitive health and function.
It’s easy to see how a vitamin D deficiency (or even low levels) can affect you from head-to-toe—whether it’s maintaining muscle mass (and muscle power), bone health, a robust immune response and maybe even help in the bedroom, your vitamin D status matters. And having enough vitamin D levels as you age is crucial to maintain strong skeletal muscles.
Pro tip: You can do a blood test to determine your blood serum D concentration levels.
Does vitamin D help with muscle weakness?
The findings of this recent study add to a large body of research showing how essential adequate vitamin D levels are for muscle strength and muscle function. As research suggests, elderly people with insufficient levels are at a higher risk for muscle weakness and impaired physical performance. Additionally, vitamin D deficiency has been linked to oxidative stress in skeletal muscle cells, resulting in muscle atrophy (and negatively impacting physical performance).
Your skeletal muscle cells need enough essential nutrients for muscle regeneration to repair muscle damage and maintain healthy muscle function—and vitamin D is one of those nutrients. It’s not the only one, though; vitamin D and magnesium are a terrific combo for skeletal muscle health, muscle strength and muscle function. Research shows that vitamin D and beta-hydroxy-beta-methylbutyrate (HMB for short) is another nutrient combo that helps support healthy skeletal muscle and preserve muscle mass.
In addition to maintaining healthy vitamin D levels, regular exercise, including resistance training, eating a balanced diet that includes plenty of protein, and ensuring your hormones are in balance (a dip in testosterone can cause loss of muscle) are excellent ways to keep your muscles strong as you age.
Where does vitamin D come from?
Your body naturally produces vitamin D as a hormone from cholesterol and UV exposure—cholesterol is a precursor or helper molecule for many hormones in the body, including vitamin D, cortisol and sex hormones. It is available as a fat-soluble vitamin and from some foods.
Is there such a thing as too much vitamin D?
Yes! Although it’s not common. The sunshine vitamin is fat-soluble, which means your body can store it. And too much vitamin D can cause an excessive amount of calcium to circulate in the blood. To avoid any adverse effects from too much vitamin D, check your 25-hydroxyvitamin D, the primary circulating form of vitamin D in your blood, regularly. Life Extension recommends optimal levels of 50 to 80 ng/mL, and levels shouldn’t exceed 100 ng/mL.
What are signs of vitamin D deficiency?
A vitamin D deficiency means your body has insufficient levels to function optimally. Vitamin D symptoms are very subtle and may not be noticeable immediately.
A clinical vitamin D deficiency could manifest in several ways, including bone pain and muscle weakness. Other vitamin D deficiency symptoms may include:
- Weak bones and skeletal muscles—Lack of vitamin D can result in low calcium levels, impacting both bone mineral density and muscle strength.
- Slow-healing wounds—Research suggests that vitamin D is crucial for producing compounds involved in healing and repairing the skin. If you notice a small cut takes a long time to heal, it may suggest a vitamin D deficiency.
- Hair loss—Severe hair loss may be a symptom of a vitamin D deficiency.
- Depression—A large body of research suggests people with a vitamin D deficiency are more vulnerable to mood disorders, including seasonal depression that can occur during winter months. Vitamin D intake can help support a healthy mood.
Pro tip: Listen to what your body tells you. Speak with your healthcare provider if you notice you get sick more often or you’re not feeling like your usual self—being proactive could help you avoid a vitamin D deficiency.
6 tips to increase vitamin D levels
Now that you understand the link between vitamin D and muscle strength a little better, let’s go over how you can ensure your body gets enough of this essential vitamin. Here are six ways you can help your body raise vitamin D levels:
- Enjoy the outdoors: Spending too much time indoors can increase the risk of a vitamin D deficiency. Remember that your body is biologically designed to make vitamin D from cholesterol and UV exposure. Enjoying time outdoors and exposing your skin to the open skies (especially when they are that forget-me-not blue!) is a terrific way to avoid a vitamin D deficiency because it prompts your body to produce vitamin D3. Of course, be mindful when you do walk out into open skies; wear sunscreen and protective garments if you’ll be spending most of your day outside.
- Keep close tabs on your D levels: You can’t fix a problem if you don’t know it exists. Empower yourself with knowledge by getting regular blood tests. Routine lab work provides a blueprint of your metabolic and physiological health, including vitamin D levels along with other critical health metrics.
- Get enough vitamin D: Daily supplementation can have better results in maintaining sufficient levels than bolus dosing, or sporadically taking very high vitamin D doses. Be sure to take doses that help raise D concentrations in blood serum levels; Life Extension recommends doses of 5,000 IU to 8,000 IU for optimal vitamin D levels.
- Choose vitamin D3 over D2: There are two dietary forms of vitamin D: cholecalciferol or vitamin D3 and ergocalciferol or D2. You’ll find vitamin D3 in animal sources and vitamin D2 in plant-based sources. However, choosing vitamin D3 has been shown to be more effective at raising 25-hydroxyvitamin D, the main form of the sunshine vitamin circulating in the blood.
- Eat vitamin D-rich foods: Unfortunately, few foods have naturally high D concentrations, and the type of food sources also matter. Plant-based choices like mushrooms and soy are rich in vitamin D2, which is not as effective in raising vitamin D levels. Meanwhile, animal sources such as eggs, fish, and grass-fed meats, are rich in vitamin D3. You can also get some vitamin D in fortified foods like milk, cereals and bread.
Summary: Vitamin D and skeletal muscle strength
Let’s recap: Vitamin D is a star player in whole-body health. Yet, insufficient levels or vitamin D deficiencies can be common, impacting muscle function and physical performance or resulting in several health concerns, including muscle weakness, osteoporosis, sarcopenia, celiac disease, lower defenses and more. This recent study shows that low vitamin D levels in people 50 and older were associated with a 78 percent increased risk of losing muscle strength. To avoid muscle weakness and other health concerns, you can be proactive and help your body maintain muscle power (and whole-body health) by ensuring your D concentrations are at sufficient levels. Eating D-rich foods, enjoying time outdoors, and daily vitamin D supplementation are excellent ways to ensure your body has enough vitamin D to avoid a deficiency and feel strong throughout your golden years.Life Extension Health Concens