Vitamin D Deficiency Symptoms in Adults: Signs, Risks and Testing

The most common vitamin D deficiency symptoms in adults are fatigue, bone pain, muscle weakness, aches or cramps, and mood changes, according to Cleveland Clinic. Many adults have no symptoms at all, which is why a simple blood test for 25-hydroxyvitamin D is the only way to know your level.

Key takeaways

• Vitamin D helps your body absorb calcium and keep bones and muscles strong.
• Symptoms are often vague: tiredness, aches, weakness and low mood.
• Adults over 65, people with darker skin, people who get little sun and those with certain gut or kidney conditions are most at risk.
• Northern winters make it hard to make vitamin D from sunlight, so food and supplements matter more from October to April.

What are the signs of vitamin D deficiency in adults?

1. Fatigue that lingers even with enough sleep.
2. Bone pain, often felt in the lower back, hips or legs.
3. Muscle weakness, which can make climbing stairs or getting up from a chair harder.
4. Muscle aches or cramps.
5. Low mood or mood changes.

Over time, a long-term shortage can soften bones (osteomalacia in adults) and contribute to bone thinning, which raises the risk of fractures. These symptoms have many possible causes, so talk to your doctor rather than guessing.

Who is most at risk of low vitamin D?

Cleveland Clinic lists these risk factors:

• Age over 65, because the skin makes less vitamin D with age.
• Darker skin, which produces less vitamin D from the same sun exposure.
• Limited sun exposure, including people who are homebound or live in care homes, and anyone in northern regions during winter.
• Higher body weight (BMI over 30).
• Conditions that affect absorption such as Crohn’s disease, celiac disease, cystic fibrosis, and kidney or liver disease, or weight-loss surgery.
• Certain medicines, including some steroids, seizure medications and cholesterol-lowering resins.

How is vitamin D deficiency diagnosed?

Doctors measure 25-hydroxyvitamin D, written 25(OH)D, with a blood test. It is not part of routine blood work for everyone, so ask your doctor if you have symptoms or risk factors. Results are reported in nmol/L in Canada and many other countries, and ng/mL in the United States. Our normal vitamin D levels chart explains how to read both.

What are the best food sources of vitamin D?

• Fatty fish such as salmon, trout, mackerel, sardines and tuna.
• Cod liver oil.
• Egg yolks and beef liver.
• UV-exposed mushrooms.
• Fortified foods such as milk and plant milks, some yogurts, orange juice and breakfast cereals (check the label).

Because few foods are naturally rich in vitamin D, many adults in northern climates use a supplement in the darker months. Cleveland Clinic notes that vitamin D3 (cholecalciferol) is available over the counter and is absorbed more easily than D2. CLE Vitamin D3 5,000 IU provides vitamin D3 for daily intake, supporting bone health and immune function. A 5,000 IU daily dose is higher than the standard daily recommendation, so check with your doctor which amount is right for you and see our guide on how much vitamin D is too much.

Can you get enough vitamin D from the sun?

In summer, short periods of sun on bare skin help the body make vitamin D. In Canada and the northern United States, the sun is too low from roughly October to April for the skin to make much vitamin D, and sunscreen, clothing and age also reduce production. Protect your skin from sunburn rather than relying on long sun exposure.

The bottom line

Vitamin D deficiency symptoms in adults are easy to miss because they are vague and build slowly. If you are often tired, achy or weak, especially in winter or if you have risk factors, ask your doctor about a 25(OH)D test, eat vitamin D-rich foods and discuss whether a supplement makes sense for you.

Frequently asked questions

Can low vitamin D cause tiredness?

Yes. Fatigue is one of the most common symptoms listed by Cleveland Clinic, although tiredness has many other causes too.

How long does it take to correct low vitamin D?

It depends on how low your level is and the dose your doctor recommends. Many people have a repeat blood test after a few months to check progress.

Is D3 better than D2?

Vitamin D3 is generally absorbed more easily and is available over the counter, while D2 usually requires a prescription.

Sources

• Cleveland Clinic: Vitamin D Deficiency
• NIH Office of Dietary Supplements: Vitamin D Fact Sheet

This article is general information, not medical advice. Talk to your doctor or pharmacist before starting any supplement, especially if you take medication or have a medical condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.