Vitamin D deficiency can be difficult to notice because symptoms may not occur for several months or years. Sometimes, you may have no symptoms at all.
Keeping that in mind, it’s still helpful to know what signs and symptoms to look for.
Frequent illness or infections
One of the most important roles of vitamin D is supporting immune health, which helps you ward off viruses and bacteria that cause illness.
Vitamin D directly interacts with the cells that are responsible for addressing infections.
If you often become sick, especially with colds or the flu, low vitamin D levels may be a contributing factor. Several large observational studies have shown a link between a deficiency and respiratory tract infections such as colds, bronchitis, and pneumonia.
A number of studies have found that taking up to 4,000 IU of vitamin D daily may reduce the risk of respiratory tract infections.
Recently, vitamin D deficiency has been linked to an increased risk of COVID-19, as well as an increased risk of experiencing severe effects from the condition. However, it is important to note that taking vitamin D supplements — at any dosage — will not prevent COVID-19.
Feeling tired can stem from a number of causes, one of which may be vitamin D deficiency.
Unlike more visible causes like stress, depression, and insomnia, vitamin D deficiency is often overlooked as a potential cause of fatigue.
One study in 480 older adults linked vitamin D deficiency with Fatigue symptoms.
Plus, a study in 39 children associated low vitamin D levels with poor sleep quality, shorter sleep duration, and delayed bedtimes.
One observational study in female nurses also found a strong connection between low vitamin D levels and self-reported fatigue. What’s more, 89% of the participants were deficient in this vitamin.
Interestingly, several studies show that supplementing with this vitamin may reduce the severity of Fatigue in people with a deficiency.
All the same, more research is needed.
Bone and back pain
Bone and lower Back pain may be symptoms of inadequate vitamin D levels.
Vitamin D helps maintain bone health by improving your body’s absorption of calcium.
One study in 98 adults with lower Back pain linked lower levels of vitamin D to more severe pain. However, a large research review found that this association was inconsistent across other similar studies.
A review of 81 studies also found that people with arthritis, muscle pain, and chronic widespread pain tended to have lower levels of vitamin D than people without these conditions.
Still, more studies are necessary.
Vitamin D deficiency has been linked to depression, especially in older adults — although some study results are conflicting.
The effects of vitamin D supplements have been mixed, but some reviews have found that they helped relieve symptoms of depression.
Still, more research is needed to understand the relationship between vitamin D and depression.
Impaired wound healing
Slow wound healing after surgery or injury may be a sign that your vitamin D levels are too low.
In fact, results from a test-tube study suggest that vitamin D increases the production of compounds that are crucial for forming new skin as part of the wound-healing process.
One review of four studies found that vitamin D deficiency compromised certain aspects of healing in people who had dental surgery.
Vitamin D’s role in controlling inflammation and addressing infections may also be important for proper healing.
One older study in 221 people, 112 of whom had diabetes-related foot infections, found that those with severe vitamin D deficiency were more likely to have higher levels of inflammatory markers that can jeopardize healing.
In a 12-week study involving 60 people with diabetes-related foot ulcers, those who took a vitamin D supplement experienced significant improvements in wound healing compared with the placebo group.
However, further research is needed.
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 women, at an increased risk of fractures.
In a large observational study in more than 1,100 middle-aged menopausal or postmenopausal women, researchers found a strong link between low vitamin D levels and low bone mineral density.
However, research on vitamin D supplementation therapy in independent older adults has yielded mixed results. While some studies show some benefits, such as reduced muscle pain, others have not found that it wards off fractures related to bone loss. One study found that women deficient in vitamin D experienced no improvement in bone mineral density when they took high dose supplements, even if their blood levels improved.
Nonetheless, adequate vitamin D intake may be a good strategy to protect your bone mass and reduce fracture risk.
Many foods and nutrients may affect hair health.
While stress is a common cause of hair loss, severe Hair loss may be the result of a disease or nutrient deficiency.
Hair loss in women is linked to low vitamin D levels, though research is lacking.
In particular, studies tie low vitamin D levels to alopecia areata, an autoimmune disease characterized by severe hair loss.
One study in people with this condition associated lower vitamin D levels with more severe hair loss. In another study in 48 people with this condition, applying a synthetic form of vitamin D topically for 12 weeks significantly increased hair regrowth.
Another research review 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.
The causes of muscle pain are often difficult to pinpoint. However, evidence suggests that vitamin D deficiency is a potential cause.
In an older study, 71% of people with chronic pain were found to have 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 pain signaling pathways, which may play a role in chronic pain.
A few studies note that high dose vitamin D supplements may reduce various types of pain in people with a vitamin D deficiency.
One 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%.
Obesity is one risk factor for vitamin D deficiency.
One 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 men.
While vitamin D deficiency may be seen in cases of obesity, further studies are needed to determine whether supplementing with this vitamin helps prevent weight gain.
Vitamin D deficiency is linked to anxiety disorders.
One review found that levels of calcidiol, a form of vitamin D, were lower in people with anxiety, as well as in those with depression.
A separate study in pregnant women found that having adequate vitamin D levels may help reduce anxiety symptoms, improve sleep quality, and even help prevent postpartum depression.