Vitamin D deficiency can cause fatigue, muscle weakness, muscle aches and bone pain, although some people have no symptoms at all. And living somewhere sunny does not rule it out: a large Thai study found vitamin D insufficiency in 64.6% of people studied in Bangkok, significantly higher than in other parts of Thailand.
If you have persistent symptoms or risk factors for vitamin D deficiency, a blood test can measure your vitamin D status. Treatment depends on how low your level is and why it is low rather than simply taking large doses of vitamin D supplements.
What Are the Symptoms of Vitamin D Deficiency?
The symptoms of vitamin D deficiency can be surprisingly vague. Some people who are deficient feel perfectly well, while others experience fatigue, bone pain, muscle weakness, aches or muscle cramps. Mood changes can also occur.
That makes symptoms alone a poor way of deciding whether you have low vitamin D. Tiredness, for example, has dozens of possible causes. If it persists, a doctor may consider vitamin D alongside other potential causes rather than assuming a supplement will fix the problem.
Severe vitamin D deficiency is more important because prolonged deficiency can interfere with normal bone mineralisation and contribute to osteomalacia in adults.
Can You Have Vitamin D Deficiency in Sunny Thailand?
Yes. Plenty of sunshine does not necessarily mean everyone gets enough vitamin D.
Research using data from 2,641 Thai adults found vitamin D insufficiency was particularly common in Bangkok. The prevalence was 64.6% in Bangkok, compared with 46.7% in other municipal areas and 33.5% outside municipal areas. People living in Bangkok also had lower average vitamin D levels than those in Thailand’s central, northern, northeastern and southern regions.
A separate review of vitamin D deficiency in Thailand also found that low vitamin D status occurs despite the country’s year-round availability of UVB sunlight.
Urban living may help explain the apparent contradiction. Living in Bangkok can mean spending much of the working day indoors, travelling in enclosed transport and limiting direct exposure to strong tropical sunlight.
What Causes Vitamin D Deficiency?
There are two broad reasons for vitamin D deficiency: you are not getting or producing enough vitamin D, or your body is having difficulty absorbing or processing it.
Sunlight is an important source because UVB exposure allows the skin to produce vitamin D. Diet provides another source, although relatively few foods naturally contain large amounts.
The risk of vitamin D deficiency can also be affected by:
- Limited exposure to sunlight
- Darker skin pigmentation
- Older age
- Poor dietary intake
- Conditions that reduce intestinal absorption
- Liver or kidney disease
Certain medications and weight-loss surgery can also affect vitamin D levels.
This is why identifying the cause can be as important as identifying the deficiency itself.
Why Is Vitamin D Important for Calcium and Bone Health?
Vitamin D is important because it allows the body to absorb and use calcium and phosphorus properly. These minerals are needed to build and maintain healthy bones.
With chronic or severe vitamin D deficiency, calcium absorption can fall. The body may compensate by taking calcium from the bones, contributing to loss of bone mineralisation. Severe deficiency can eventually result in osteomalacia in adults, while deficiency during childhood can cause rickets.
Vitamin D also plays roles in normal muscle, nervous system and immune function.
How Do You Check Your Vitamin D Status?
Vitamin D status is normally assessed with a blood test measuring 25-hydroxyvitamin D [25(OH)D].
The result tells your doctor the amount of circulating vitamin D in your blood. It can then be considered alongside your symptoms, medical history, diet, medications and other risk factors.
This distinction matters because definitions of vitamin D insufficiency and deficiency are not identical across every medical organisation or study. For example, the major Thai population study defined insufficiency as below 30 ng/mL and deficiency as below 20 ng/mL.
Rather than trying to diagnose yourself from symptoms, testing provides an objective measurement of your vitamin D level.
How Can You Get Enough Vitamin D?
Vitamin D comes principally from sunlight, food and supplements.
Vitamin D From the Sun
Your skin can produce vitamin D when exposed to UVB radiation. How much vitamin D production occurs depends on several factors, including skin pigmentation, age, clothing, location and the amount of skin exposed.
But living in Thailand does not mean you should deliberately spend long periods in strong sunshine. Excessive UV exposure has its own health risks, and the Thai research shows that abundant sunshine alone does not guarantee adequate vitamin D status.
Dietary Sources of Vitamin D
Natural sources of vitamin D include fatty fish such as salmon, sardines and mackerel. Egg yolks contain smaller amounts, while some foods are fortified with vitamin D.
Vitamin D2 and vitamin D3 are the two main forms found in foods and supplements. Vitamin D3 is also the form produced by the skin following sunlight exposure.
For someone with a significant deficiency, however, changing diet alone may not provide the amount of vitamin D needed to correct it.
Treatment of Vitamin D Deficiency
The treatment of vitamin D deficiency depends on the person’s vitamin D level, the underlying cause and their individual health circumstances.
Vitamin D supplementation is commonly used to treat deficiency. Dietary changes and appropriate sunlight exposure can also contribute to maintaining adequate vitamin D levels.
There isn’t one appropriate dose for everyone. Someone with severe vitamin D deficiency may need a different treatment approach from someone trying to maintain vitamin D sufficiency.
This is where medical review matters. Instead of simply taking vitamin D supplements indefinitely, testing can identify a deficiency and follow-up testing can show whether treatment has actually improved your levels.
How Much Vitamin D Should You Take?
There is no single supplement dose that is appropriate for every person with vitamin D deficiency.
Requirements vary with age, existing vitamin D status, diet, medical conditions and the reason levels are low. The doses of vitamin D used to treat a diagnosed deficiency can also differ from ordinary nutritional intake.
This is particularly important if you are considering larger doses of vitamin D. More is not automatically better, and taking high doses without knowing your vitamin D level is unnecessary for many people.
Can Taking Too Much Vitamin D Cause Vitamin D Toxicity?
Yes. Vitamin D toxicity can occur when excessive amounts of vitamin D supplements are taken, particularly in high doses over time.
Because vitamin D increases calcium absorption, excessive supplementation can cause abnormally high blood calcium. This can cause health problems rather than provide additional benefits.
Vitamin D toxicity is generally associated with excessive supplementation rather than normal food intake or ordinary sunlight exposure.
If you think you may be deficient, testing first gives you a much better basis for deciding whether supplementation is necessary.
Prevention and Treatment: When Should You See a Doctor to treat vitamin d deficiency?
You do not need to test vitamin D simply because you occasionally feel tired. But persistent fatigue, muscle weakness, bone discomfort or several risk factors for vitamin D deficiency may justify discussing it with a doctor.
Testing may be particularly useful when symptoms cannot otherwise be explained or when a medical condition, medication or lifestyle factor increases your risk.
At WellMed Bangkok Clinic, a doctor can review your symptoms and medical history and determine whether vitamin D testing or other blood tests are appropriate. If a deficiency is identified, your results can be explained and an appropriate treatment and follow-up plan discussed.
Conclusion on the risk of vitamin d deficiency
Vitamin D deficiency is possible even in sunny Thailand, and research suggests that low vitamin D status is particularly common among people living in Bangkok.
If you have symptoms or risk factors, the useful first question is not how much vitamin D you should take, but whether you are actually deficient. A blood test provides that answer and allows treatment to be based on your vitamin D status rather than guesswork.
About WellMed Bangkok Clinic
WellMed Bangkok Clinic provides doctor consultations and blood testing for patients in Bangkok, including local residents, expats and visitors.
If you are concerned about vitamin D deficiency, a doctor can review your symptoms and risk factors, arrange appropriate testing and explain your results. Where treatment is required, this allows supplementation and follow-up to be based on your individual results rather than assumptions.
Frequently Asked Questions About Vitamin D Deficiency
These are some of the most common questions people ask about low vitamin D, its symptoms and how to improve vitamin D levels.
What happens when your calcium and vitamin D is low?
Low vitamin D may cause no obvious symptoms, but deficiency can cause fatigue, muscle weakness, aches and bone pain. Severe or prolonged deficiency can affect calcium absorption and weaken bones.
What are the signs of low vitamin D?
Possible symptoms of vitamin D deficiency include fatigue, bone pain, muscle weakness, muscle aches or cramps and mood changes. However, these symptoms can have many other causes, so a blood test is needed to determine your vitamin D status.
How can I increase my vitamin D levels?
Vitamin D can come from sunlight, foods such as fatty fish and fortified foods, and vitamin D supplements. If a blood test shows you are deficient, a doctor can recommend an appropriate approach based on your level and individual risk factors.
What foods are rich in vitamin D?
Fatty fish such as salmon, sardines and mackerel are useful dietary sources of vitamin D. Egg yolks and foods fortified with vitamin D can also contribute to your overall vitamin D intake.
Are two eggs a day enough vitamin D?
Eggs contain vitamin D, but they should not be relied upon as your only source. Whether you get enough vitamin D depends on your complete diet, sunlight exposure and individual health circumstances.
How does vitamin D affect mood?
Low vitamin D status has been associated with mood changes, including depression, but mood problems have many possible causes. Vitamin D supplements should therefore not be treated as a substitute for appropriate assessment when someone has persistent mood symptoms.
Can low vitamin D affect sleep?
Research has explored a relationship between vitamin D and sleep, but poor sleep does not by itself mean you are vitamin D deficient. Persistent sleep problems can have many causes and should be assessed accordingly.
What drains vitamin D from your body?
Vitamin D is not usually “drained” from the body by one particular thing. Low levels can result from inadequate sunlight or dietary intake, reduced absorption, certain medications, or liver and kidney conditions that affect how vitamin D is processed.
How do I know if I have vitamin D deficiency?
Symptoms cannot reliably tell you whether you are deficient. A blood test measuring 25-hydroxyvitamin D can establish your vitamin D status and help determine whether treatment is necessary.
Sources
The medical information in this article was informed by the Cleveland Clinic overview of vitamin D deficiency, a peer-reviewed study of vitamin D status across Thailand, a peer-reviewed review of vitamin D deficiency in Thailand and guidance published by the Thai Society for Pediatric Endocrinology.
