Is vitamin D good for muscle growth & strength?

As vitamin D deficiency is common among athletes, taking vitamin D supplements might help you build muscle mass, as vitamin D:

  • helps your muscles recover faster,
  • affects muscle strength,
  • boosts testosterone synthesis,
  • keeps you healthy, and
  • is vital for muscle metabolism!

Can vitamin D affect muscle growth?

Vitamin D is necessary for normal growth of muscle fibers and for proper muscle metabolism. Therefore, all athletes should check their serum vitamin D levels. Athletes of bodybuilding, as well, as vitamin D deficiency can seriously affect muscle strength and even lead to muscle weakness or pain.[1]

Furthermore, vitamin D is important not only for the proper musculoskeletal function, but also for improving physical performance.[2]

Moreover, high serum vitamin D levels seem to be beneficial for muscle growth.[3]

Probably, athletes with high serum vitamin D levels won’t benefit from taking vitamin D supplements. If you have high levels of vitamin D, taking vitamin D supplements won’t help you build muscle mass faster or increase muscle strength.[4]

On the contrary, vitamin D deficiency may cause decrease in muscle function and performance! Hence, athletes with vitamin D deficiency can benefit from vitamin D supplementation.

Can vitamin D deficiency cause muscle weakness?

Although most athletes follow a healthy well-balanced diet, vitamin D deficiency is pretty common in athletes of all sports. In bodybuilding athletes, as well.

Vitamin D deficiency is among the most common nutrient deficiencies. After all, it’s estimated that about 1 billion people have vitamin D insufficiency or deficiency.[5]

Even many elite competitive athletes are vitamin D deficient. Vitamin D deficiency may increase the risk of:[6,7]

  • stress fractures,
  • structural pathology of muscle tissue,
  • injury,
  • inflammation,
  • illness,
  • gaining weight,
  • delayed muscle recovery,
  • worse sport performance.

So, vitamin D deficiency may inhibit athletes from working out regularly or following intense workouts. Hence, it may cause decreased athletic performance.

Therefore, it’s vital for athletes to check their serum vitamin D levels regularly. In case of vitamin D deficiency, taking vitamin D supplements might benefit muscle growth, muscle recovery, or muscle strength.

Moreover, corticosteroid medications which are often prescribed to reduce inflammation can impair vitamin D metabolism. As inflammations are common in athletes, frequent medication may cause vitamin D deficiency. According to a study, people who take steroid medication have twice the risk of vitamin D deficiency.[1]

Vitamin D for bodybuilding

Athletes of bodybuilding should be extra careful about their serum vitamin D levels, as vitamin D is highly associated with type II muscle fiber growth. Also, known as fast-twitch fibers.

Vitamin D deficiency may lead to atrophy of type II muscle fibers. Luckily, vitamin D supplementation can significantly improve the development of type II muscle fibers.[6]

There are two types of muscle fibers. The slow-twitch (or type I) and fast-twitch (or type II). Long-distance sports, such as running or cycling demand mainly slow-twitch fibers. On the other hand, fast-twitch fibers are necessary for sports with quick powerful movements, such as weightlifting, bodybuilding, or sprinting.

Can vitamin D improve athletic performance?

Normal serum vitamin D levels have been linked to increased jump height, velocity and power. Hence, vitamin D supplementation can affect muscle performance:[6]

  • professional soccer players increased their vertical jump and improved their sprint times.
  • ballet dancers had a 7% higher vertical jump and an 18% increase in isometric strength.
  • judo athletes had a 13% increase in muscle strength!

Moreover, zinc is necessary for athletes, as it helps the body to build muscle mass, decrease recovery time after exercise, increase muscle strength, and improve endurance exercise performances!

Can vitamin D deficiency cause muscle cramps?

Vitamin D deficiency can cause muscle cramps, as vitamin D promotes calcium absorption in the gut. Also, vitamin D maintains adequate serum calcium and phosphate concentrations which are vital for preventing cramps and spasms.

Moreover, calcium and phosphate are vital for strong bones.[1]

Can vitamin D decrease the risk of injury?

Adequate serum vitamin D levels seem to decrease the risk of injury among athletes. Furthermore, low levels of vitamin D have been linked to muscle weakness after injury. Vitamin D supplementation helped:[6]

  • ballet dancers sustain fewer injuries, compared to dancers who didn’t take vitamin D supplements.  
  • swimmers to have decreased risk of connective tissue and muscle injuries.

Also, injury incidence was lower in summer, as people get high amounts of vitamin D from sun exposure.

Moreover, vitamin D seems to protect athletes from missing workouts and even competitions. Especially elite athletes of endurance sports can benefit the most, as the immune system is suppressed and the body is pretty vulnerable to infection.

On the other hand, vitamin C supplementation may not be good for athletes who want muscle growth.

What’s the best serum vitamin D level for athletes?

The recommended daily intake of vitamin D is 600 IU. Furthermore, we shouldn’t take more than 4,000 IU of vitamin D daily without checking our serum vitamin D levels.

Excessive vitamin D can be bad for health. Serum concentrations greater than 125 nmol/L (or 50 ng/mL) can lead to adverse effects, such as muscle weakness, pain, loss of appetite, dehydration, and many more.

nmol/Lng/mLHealth status
less than 30less than 12severe deficiency
between 30-50between 12-20inadequate
between 50-125between 20-50adequate
higher than 125higher than 50potential adverse effects
higher than 150higher than 60may cause toxicity
Serum vitamin D-25(OH) concentration.

Optimal serum vitamin D levels for athletes are about 120 nmol/L (or 48 ng/mL). Adequate amounts of vitamin D are good for muscle metabolism and growth of muscle fibers! Lower levels may affect muscle strength and lead to muscle weakness or even pain.

Athletes with optimal vitamin D levels have a lower risk of:[6,7,8]

  • upper respiratory tract infections,
  • fewer days experiencing illness,
  • fatigue bone stress fracture,
  • muscle injuries,
  • stress fractures.

What’s the best dosage of vitamin D for bodybuilding?

Although the recommended daily intake of vitamin D is 600 IU, the Endocrinology Society estimated that this dosage isn’t enough. They recommend a daily vitamin D intake of 1,500–2,200 IU for people who don’t have adequate sun exposure![7]

Athletes don’t need a higher daily vitamin D dosage. As other people, athletes should check their serum vitamin D levels regularly. The best vitamin D levels are about 120 nmol/L (or 48 ng/mL).

Above all, you should consult your health care provider before taking a vitamin D supplement for a long time. Certainly, vitamin D supplements are considered pretty safe.

Athletes with vitamin D deficiency could take up to 50,000 IU of vitamin D per week for 2 months. After this treatment, athletes should check again their serum vitamin D levels. Your doctor may consult you to repeat the treatment, if the vitamin D levels are still low.[6]

Most noteworthy, sun exposure should be the main source of vitamin D. Unfortunately, only a few foods are good sources of vitamin D.

Furthermore, a healthy well-balanced diet, rich in essential minerals and micronutrients, such as magnesium, is good for enhancing activation of vitamin D.[7]