Vitamin D deficiency can be surprisingly easy to miss. You may feel tired, notice more aches than usual, or simply feel like your body is not working the way it normally does. It is tempting to blame these changes on stress, poor sleep, a busy routine, or getting older.
Sometimes, however, low vitamin D is part of the picture.
The tricky part is that many people with vitamin D deficiency have no obvious symptoms at all. When symptoms do appear, they can be vague. Knowing the possible warning signs can help you recognize when it may be worth getting your vitamin D level checked.
What Is Vitamin D Deficiency?
Vitamin D deficiency means your body does not have enough vitamin D to support its normal functions.
Vitamin D is best known for helping the body absorb calcium and maintain healthy bones. It also contributes to normal muscle function and plays a role in immune system activity.
Your body can make vitamin D when your skin is exposed to sunlight. You can also get it from certain foods, fortified foods, and supplements.
When vitamin D levels remain too low, bone and muscle health can be affected.
What Are the Symptoms of Vitamin D Deficiency?
Symptoms can vary from person to person. Some people experience several of these signs, while others experience none.
1. Bone Pain
Persistent bone pain can be one of the signs associated with significant vitamin D deficiency.
Low vitamin D can interfere with calcium absorption and normal bone mineralization. In adults, severe deficiency can contribute to osteomalacia, a condition in which bones become softer and weaker.
A study of 118 adults with tibial bone pain and 114 controls found that vitamin D deficiency was more common among people with pain. The study also found that lower vitamin D levels were linked to a greater likelihood of tibial bone pain and tenderness.
However, bone pain has many possible causes, so it should not automatically be attributed to vitamin D deficiency.
2. Muscle Weakness and Aches
Vitamin D deficiency can affect muscle function and may cause muscle weakness or aches, particularly when deficiency is severe or has led to osteomalacia.
You might notice that everyday activities, such as climbing stairs, getting up from a chair, or carrying something, feel more difficult than usual. Some people may also experience general muscle soreness or discomfort.
Studies of people with severe vitamin D deficiency and osteomalacia have reported muscle weakness and musculoskeletal pain, with some patients experiencing improvement after vitamin D treatment.
However, muscle weakness and aches are nonspecific and can occur for many reasons, including exercise, stress, medications, injuries, infections, and other health conditions. These symptoms alone cannot tell you whether your vitamin D level is low.
3. Fatigue
Feeling unusually tired even after getting enough rest can sometimes occur with vitamin D deficiency.
You may notice that your energy feels consistently low, or that everyday tasks seem to take more effort than usual.
Research has found a link between low vitamin D levels and fatigue. In a study of 120 people with vitamin D deficiency and fatigue, those who received vitamin D3 reported greater improvement in fatigue after four weeks than those who received a placebo.
Still, fatigue is a very nonspecific symptom. Poor sleep, anemia, thyroid problems, stress, infections, and other nutritional or health conditions can leave you feeling just as tired.
So if your fatigue persists, don’t automatically assume vitamin D is the reason. Looking at the bigger picture and identifying the underlying cause is important.
4. Getting Sick More Often
Vitamin D plays an important role in normal immune system function.
Research has found an association between low vitamin D levels and a greater risk of some respiratory infections. However, this does not mean that vitamin D deficiency is the reason someone gets sick frequently.
Some earlier research suggested that vitamin D supplementation might modestly reduce the risk of respiratory infections, particularly in certain groups. However, newer research has not confirmed a statistically significant overall protective effect.
So the goal is to maintain adequate vitamin D levels, rather than taking increasingly large amounts in an attempt to prevent infections.
5. Bone Fractures
Prolonged or severe vitamin D deficiency can interfere with normal bone mineralization, causing bones to become softer and weaker. In adults, severe deficiency can lead to osteomalacia, which can increase the risk of bone pain and fragility fractures.
This can be particularly concerning in older adults, who may already have a higher risk of falls and fractures.
For instance, a study of 287 elderly women with low-impact fractures found that vitamin D deficiency was associated with cortical bone loss and a greater severity of fractures. Higher vitamin D levels were linked to lower odds of more severe fractures.
A fracture after a relatively minor injury should be evaluated by a healthcare professional rather than automatically attributed to low vitamin D.
6. Slow Growth in Children
Children need vitamin D for normal bone development.
Significant vitamin D deficiency during childhood can cause rickets, a condition in which growing bones become soft and poorly mineralized.
Signs can include bone pain, soft or weak bones, skeletal deformities, poor growth, and developmental delays. Severe rickets can also cause complications such as seizures related to low calcium levels, muscle spasms, heart problems, and dental abnormalities.
Children with suspected vitamin D deficiency should be evaluated by a healthcare professional rather than treated with high-dose supplements without guidance.
7. Mood Changes
Low vitamin D levels have been associated with depression and other mood-related symptoms in some studies. A large review of observational studies found that people with lower vitamin D levels were more likely to have depression.
However, the relationship is complicated. An association does not mean that vitamin D deficiency causes depression, and studies testing whether vitamin D supplements improve depressive symptoms have produced mixed results.
Feeling depressed or experiencing persistent changes in mood does not automatically mean you have a vitamin D deficiency. Vitamin D supplements are also not a replacement for appropriate treatment for depression.
If you are experiencing ongoing low mood, loss of interest, hopelessness, or other significant emotional changes, seek appropriate professional support.
What Does Vitamin D Deficiency Feel Like?
There is no single feeling that tells you, “Your vitamin D is low.” Some people with vitamin D deficiency may have no noticeable symptoms, while others may experience fatigue, muscle weakness, muscle aches, bone pain, changes in mood, or other symptoms.
Because these symptoms can have many different causes, they cannot confirm vitamin D deficiency on their own. A blood test measuring 25-hydroxyvitamin D, also written as 25(OH)D, is commonly used to assess vitamin D status.
Talk with a healthcare professional about testing if you have symptoms that could be related to deficiency, risk factors for low vitamin D, problems with bone health, unexplained muscle weakness, or a condition that may interfere with vitamin D absorption.
What Causes Vitamin D Deficiency?
Several factors can contribute to low vitamin D levels, such as:
- Limited sun exposure
- Darker skin
- Not getting enough vitamin D from food
- Certain digestive conditions
- Older age
- Obesity
Can Vitamin D Deficiency Be Treated?
Yes.
Vitamin D deficiency can usually be treated by increasing vitamin D intake through supplements, fortified foods, diet, or a combination of these approaches.
The amount of supplementation needed depends on how low the level is and other individual factors.
Someone with a confirmed deficiency may need a higher dose for a limited period, followed by a lower maintenance dose.
Do not assume that higher doses will correct vitamin D deficiency faster. Excessive vitamin D intake can cause dangerously high calcium levels and, in severe cases, kidney problems, heart complications, and other serious health effects.
Sunlight can also help your body make vitamin D, although the amount produced varies widely between individuals.
The Bottom Line
Vitamin D deficiency may cause no symptoms, while its symptoms can overlap with many other health conditions.
If you suspect your vitamin D level may be low, a 25-hydroxyvitamin D blood test can help determine your vitamin D status more reliably than symptoms alone.
If a deficiency is confirmed, appropriate treatment may include dietary changes, fortified foods, supplements, or other measures based on the underlying cause and your individual needs.