Medically reviewed by Kevin Martinez, M.D.
Written by Louisa Richards
June 3, 2020

A person may not realize that they have a vitamin D deficiency, but there are some symptoms to look out for.

This article explores the signs and symptoms of a vitamin D deficiency, as well as possible complications, treatments, and when to see a doctor.

About vitamin D

Some sources of vitamin D include milk, white mushrooms, and cooked sockeye salmon.
Vitamin D is important for health. Some of its roles in the body include:

  • helping with the absorption of calcium
  • maintaining healthy bones
  • regulating genes and cell growth
  • preventing rickets and osteoporosis
  • modulating the immune system

Vitamin D is naturally present in very few foods, and often in amounts too low to help a person meet their daily recommended intake. In response, manufacturers fortify several foods with the vitamin.

According to a 2020 review, 50% of the worldwide population has insufficient levels of vitamin D. In the United States, 35% of adults have the deficiency.

The prevalence of vitamin D deficiency is highest among older adults, people with obesity, and people in hospitals and other care facilities.

Signs and symptoms of the deficiency

Many people with vitamin D deficiency have no symptoms. However, the deficiency can cause the following issues.

- Frequent infections or illnesses

- Vitamin D helps support the immune system — it plays a role in regulating immune function and inhibiting inflammatory reactions.

It can also help prevent infections in the upper respiratory tract.

Fatigue and muscle weakness

Because vitamin D is key to bone health, an insufficient amount can cause bone and muscle weakness, which can lead to fatigue.

Researchers behind a 2014 study that included 174 participants with fatigue found that taking supplementary vitamin D for 5 weeks significantly improved fatigue symptoms.

Bone and joint pain

Vitamin D can increase bone mass and prevent bone loss. If someone has bone and joint pain, it may indicate a vitamin D deficiency.

Joint pain could also result from issues such as rheumatoid arthritis. A 2012 study linked vitamin D deficiency with an increased risk of developing the condition.

Fractures

Adequate vitamin D in the body helps maintain bone strength by supporting the absorption of calcium.

According to the National Osteoporosis Foundation, this is particularly important for females after menopause, which can cause bone density to decrease and the risk of osteoporosis to increase.

If someone has a fracture, the doctor might test their vitamin D level, depending on the person’s age and health history.

Depression

The authors of a 2019 review have found that lower levels of vitamin D may increase the risk of depression.

There are vitamin D receptors in the brain, and the research indicates that the vitamin has a protective anti-inflammatory effect.

As a result, the scientists conclude, a person with very low vitamin D levels and depression may benefit from taking a supplement of the vitamin.