Vitamin D is often called the sunshine vitamin, but its importance goes far beyond sunlight.
It helps your body absorb calcium, supports healthy bones, and contributes to normal muscle and immune function.
As we age, our skin becomes less efficient at producing vitamin D from sunlight. This means older adults may be at greater risk of deficiency, especially if they spend most of their time indoors.
But how can you tell when your vitamin D levels are too low?
Here are seven possible warning signs—and one common skin symptom that is often misunderstood.
1. Persistent Muscle Weakness
One of the more important effects of vitamin D deficiency involves muscle function.
People with low vitamin D levels may experience muscle weakness, especially in the legs.
Everyday activities such as climbing stairs or getting out of a chair may become more difficult.
However, weakness has many possible causes, so it shouldn’t automatically be blamed on vitamin D.
2. Bone Pain or Tenderness
Vitamin D helps your body absorb calcium and maintain normal bone mineralization.
Severe or prolonged deficiency can contribute to osteomalacia, a condition in which bones become inadequately mineralized.
This may cause aching or tenderness, sometimes involving the hips, pelvis, legs, or lower back.
Persistent bone pain deserves medical evaluation.
3. Feeling Tired More Often
Fatigue is sometimes reported by people with low vitamin D levels.
Some studies have found associations between vitamin D deficiency and tiredness, but fatigue alone is not a reliable diagnostic sign.
Poor sleep, anemia, thyroid conditions, medications, and many other factors can also contribute.
4. Frequent Falls or Difficulty Walking
Severe vitamin D deficiency can impair muscle function and contribute to difficulty walking.
For older adults, muscle weakness can increase the risk of falls.
However, balance problems can also result from neurological conditions, medication side effects, vision changes, and other medical issues.
Vitamin D supplements do not reliably prevent falls in people who already have adequate levels.
5. Muscle Aches and Cramps
Some people with vitamin D deficiency experience muscle discomfort.
However, cramps and aches are nonspecific symptoms.
Dehydration, medication effects, nerve problems, and other nutritional deficiencies may produce similar complaints.
If symptoms persist, identifying the underlying cause is more useful than taking high-dose supplements without testing.
6. Fragile Bones and Fractures
Vitamin D deficiency can contribute to poor bone health, particularly when combined with inadequate calcium intake.
Over time, this may increase the risk of fractures.
Older adults with osteoporosis, repeated fractures, or conditions affecting nutrient absorption may need individualized assessment of their vitamin D status.
Bone strength also depends on physical activity, nutrition, hormones, and other factors.
7. Mood Changes
Some observational studies have found associations between low vitamin D levels and depressive symptoms.
However, this doesn’t prove that vitamin D deficiency causes depression.
Clinical trials haven’t consistently shown that supplementation improves mood in people without a confirmed deficiency.
Persistent sadness, loss of interest, or other significant mood changes should be assessed rather than attributed solely to vitamin levels.
Does Vitamin D Deficiency Cause Severely Dry, Peeling Skin?
The image above shows extensive scaling and peeling on the lower legs.
This appearance is not a recognized, specific sign of vitamin D deficiency.
Severe dry or scaly skin can occur with conditions such as eczema, ichthyosis, psoriasis, or other dermatological disorders.
Vitamin D plays a role in skin biology, but you cannot diagnose deficiency by looking at someone’s legs.
If your skin develops thick scales, cracks, redness, or persistent peeling, a dermatologist can help determine the cause.
How Can You Find Out If Your Vitamin D Is Low?
A blood test measuring 25-hydroxyvitamin D [25(OH)D] can assess vitamin D status when testing is clinically indicated.
Not everyone needs routine screening, and results should be interpreted alongside symptoms, medical history, and risk factors.
People with osteoporosis, malabsorption disorders, or certain other medical conditions may be more likely to benefit from testing.
Foods That Provide Vitamin D
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Dietary sources include fatty fish such as salmon and trout, egg yolks, fortified dairy products or plant-based alternatives, and some UV-exposed mushrooms.
Vitamin D supplements may be appropriate for certain older adults, but the dose depends on individual circumstances.
For adults aged 71 and older, the U.S. recommended dietary allowance is generally 800 IU (20 micrograms) daily.
Avoid taking high doses without medical guidance because excessive vitamin D can cause dangerously elevated calcium levels and kidney problems.
The Bottom Line
Vitamin D deficiency can affect bone and muscle health, and severe deficiency may contribute to weakness, bone pain, and mobility problems.
But these seven symptoms do not confirm a deficiency, and severely peeling skin—like that shown in the image—is not a reliable diagnostic sign.
The most effective approach is to consider your risk factors, seek medical evaluation when symptoms are concerning, and maintain adequate vitamin D through food or appropriate supplementation.
Recognizing possible warning signs matters, but finding the correct cause matters even more.
