Symptoms of vitamin D deficiency may include fatigue, frequent illness, anxiety, bone pain, and slower wound healing, among others. Treatments may include dietary changes or taking supplements.

Vitamin D is sometimes called the sunshine vitamin because your body makes it from cholesterol when your skin is exposed to sunlight.

It’s a fat-soluble vitamin that plays critical roles in the proper functioning of your body, including bone health and immunity. It may even help prevent cancer and protect against several chronic conditions, including:

• bone loss
• depression
• type 2 diabetes
• heart disease
• multiple sclerosis

Vitamin D deficiency is typically defined as having blood levels below 20 ng/ml, while levels from 21–29 ng/mL are considered insufficient. Most adults should get 1,500-2,000 international units (IU) of vitamin D daily.

However, vitamin D deficiency is one of the most common nutritional deficiencies worldwide. For example, nearly 42% of adults in the United States have a vitamin D deficiency. This figure rises to almost 63% in Hispanic adults and 82% in African American adults.

Keep reading to learn more about the symptoms and treatments for vitamin D deficiency.

What are the symptoms of vitamin D deficiency?

Frequent illness or infections

Vitamin D directly interacts with the cells responsible for addressing infections. If you often become sick, low vitamin D levels may be a contributing factor.

Research suggests there’s a link between vitamin D deficiency and respiratory tract infections, such as the common cold, bronchitis, and.

A 2020 review also found that vitamin D deficiency has been linked to several viral diseases, such as:

• hepatitis
• flu
• COVID-19

A 2019 review of 25 studies found that vitamin D supplementation helped reduce the risk of respiratory tract infections. It was even more beneficial for people with a blood concentration of less than 25 nmol/l, or very low levels of vitamin D.

Vitamin D research has shown that certain levels may help reduce the risks of respiratory infections. However, it’s best to speak with a healthcare professional if you’re experiencing frequent infections or illness without any known cause. They could discuss any supplements and appropriate vaccines for your overall health.

Fatigue and tiredness

Research suggests that vitamin D deficiency may cause fatigue. For example:

• A 2019 study in 480 older adults linked vitamin D deficiency with fatigue symptoms.
• A 2020 study in 39 children associated low vitamin D levels with poor sleep quality, shorter sleep duration, and delayed bedtimes. These may lead to increased fatigue.
• A 2015 study in female nurses found a connection between low vitamin D levels and self-reported fatigue. What’s more, 89% of the participants were deficient in this vitamin.

Research suggests that vitamin D supplementation may reduce the severity of fatigue in people with a deficiency.

Bone and back pain

Vitamin D helps maintain bone health by improving your body’s absorption of calcium. Bone and lower back pain may be symptoms of vitamin D deficiency.

A 2018 review of 81 studies found that people with arthritis, muscle pain, and chronic widespread pain tended to have lower levels of vitamin D than people without these conditions.

Similarly, a 2018 study in 98 adults with lower back pain linked lower levels of vitamin D to more severe pain. However, a large 2017 review found that this association was inconsistent across other similar studies.

More studies are necessary.

Anxiety and depression

Vitamin D deficiency has been associated with anxiety and depression, especially in older adults. However, some study results are conflicting and more research is needed.

The effects of vitamin D supplements have also been mixed, but some reviews from 2014, 2019, and 2021 have found that they helped relieve symptoms of depression.

Impaired wound healing

Slow wound healing after surgery or injury may be a sign that your vitamin D levels are too low. For example, a 2019 review found that vitamin D deficiency compromised certain aspects of healing in people who had dental surgery.

This may be because vitamin D increase the production of compounds that are crucial for forming new skin as part of the wound-healing process.

Vitamin D’s role in controlling inflammation and addressing infections may also be important for proper healing.

For example, a 2014 study in 221 people found that those with severe vitamin D deficiency were more likely to have higher levels of inflammatory markers that can jeopardize healing.

Similarly, in a 12-week study involving 60 people with diabetes-related foot ulcers, those who took vitamin D supplements experienced significant improvements in wound healing compared with the placebo group.

However, further research is needed.

Bone loss

Vitamin D plays a crucial role in calcium absorption and bone metabolism. This is important because taking vitamin D and calcium at the same time helps your body maximize absorption.

Low bone mineral density is an indication that your bones have lost calcium and other minerals. This places older adults, especially females, at an increased risk of fractures.

Vitamin D deficiency may also increase your risk of developing bone diseases like osteoporosis and sarcopenia (muscle loss).

However, research on vitamin D supplementation therapy in independent older adults has yielded mixed results. For example, a 2021 review found some benefits, such as reduced muscle pain, while a 2017 review found that it doesn’t ward off fractures related to bone loss.

Speak with a healthcare professional about vitamin D supplementation if you’re experiencing bone loss.

Hair loss

Research suggests that hair loss may result from nutrient deficiencies. In particular, studies tie low vitamin D levels to alopecia areata, an autoimmune disease characterized by severe hair loss.

A 2015 study in 48 people with this condition found that applying a synthetic form of vitamin D topically for 12 weeks significantly increased hair regrowth.

A 2021 review also found that vitamin D levels may have an inverse relationship with non-scarring hair loss. This means the higher the vitamin D levels, the less hair loss detected in the study, and vice versa.

Muscle pain

The causes of muscle pain are often difficult to pinpoint. However, vitamin D deficiency may be a potential cause.

A 2014 study found that 71% of people with chronic pain had a deficiency in the vitamin.

The vitamin D receptor is present in nerve cells called nociceptors, which sense pain. This vitamin may also be involved in your body’s pains signaling pathways, which may play a role in chronic pain.

A 2019 study found that high dose vitamin D supplements may reduce various types of pain in people with a vitamin D deficiency. Similarly, a 2015 study in 120 children with vitamin D deficiency who had growing pains found that a single dose of this vitamin reduced pain scores by an average of 57%.

Weight gain

Obesity is a risk factor for vitamin D deficiency.

A 2020 study in adults found a possible link between low vitamin D status and both belly fat and increased weight, although these effects were more pronounced in males.