Vitamin D Deficiency: Causes, Symptoms and Solutions

What is Vitamin D Deficiency?

Vitamin D deficiency happens when the body does not have enough vitamin D, which can reduce calcium absorption and, in some cases, lead to low blood calcium levels that may affect bone health. Many people have no obvious symptoms at first, but prolonged or severe deficiency can contribute to weak bones, bone or muscle discomfort and muscle weakness. In children, severe deficiency can cause rickets.^[2,3]

Vitamin D is sometimes called the “sunshine vitamin” because the skin can produce it when exposed to ultraviolet B (UVB) radiation from sunlight. Vitamin D can also come from food and supplementation.^[2]  Vitamin D is essential for calcium absorption and normal bone mineralisation. It contributes to normal muscle and other physiological functions. ^[6,7] Despite Malaysia’s abundant sunshine, low vitamin D levels remain common in several population groups.^[2]

What causes vitamin D deficiency?

Vitamin D deficiency can occur when the body does not produce enough vitamin D, dietary intake is low, absorption is reduced, or the body has difficulty converting vitamin D into forms it can use.^[3]

1. Limited sunlight exposure. People who spend most of their time indoors or regularly cover most of their skin may produce less vitamin D from sunlight. Older age and higher levels of skin melanin can also reduce vitamin D production.^[2,3]
2. Low vitamin D intake. Relatively few foods naturally contain large amounts of vitamin D. People who rarely consume fatty fish, eggs or vitamin D-fortified foods may obtain less vitamin D through their diet.^[2,6]
3. Problems absorbing vitamin D. Conditions that interfere with fat absorption can increase deficiency risk. Examples include coeliac disease, inflammatory bowel disease, cystic fibrosis, chronic pancreatic disorders and previous gastric bypass surgery.^[3]
4. Liver or kidney disease. Vitamin D undergoes processing in the liver and kidneys before the body can use it effectively. Liver or kidney disease can interfere with these processes.^[3]
5. Certain medicines. Some medicines can affect vitamin D metabolism, including certain anticonvulsants and other long-term therapies. Do not stop or change a medicine yourself; ask a healthcare professional whether monitoring or supplementation is appropriate.^[3]
6. Other factors that may increase risk. Older adults and some individuals with obesity may be more likely to have low vitamin D levels.^[3,5]

What are the symptoms of vitamin D deficiency?

Many people with vitamin D deficiency may not notice symptoms. When deficiency becomes severe or persists for a long time, possible signs include:^[3]

• bone pain;
• muscle weakness or muscle discomfort;
• osteomalacia, in which adult bones become poorly mineralised; and
• an increased tendency to falls or fractures in susceptible older adults.

In children, vitamin D deficiency can lead to rickets, which affects normal bone development. ^[2,3]

How do you know if you have vitamin D deficiency?

When testing is required, vitamin D status is usually assessed with a blood test measuring serum 25-hydroxyvitamin D, or 25(OH)D. This is a biomarker used to evaluate vitamin D status.^[5,6] If you have symptoms, osteoporosis, a malabsorption condition, kidney or liver disease, previous bariatric surgery or another reason to suspect deficiency, speak with a healthcare professional about whether testing is appropriate.^[5,7]

Managing Vitamin D Deficiency

Vitamin D supplementation

Vitamin D3, or cholecalciferol, is commonly used to manage vitamin D deficiency. The amount needed can vary depending on factors such as age and individual needs, and supplementation requirements may differ between individuals. Speak to your healthcare provider for advice on suitable supplementation for you.^[4,5]

Dietary sources

Food alone may not correct deficiency, but it can contribute to maintaining vitamin D intake. Useful sources include fatty fish such as salmon, mackerel and sardines, fish liver oils, egg yolks and foods fortified with vitamin D. Some UV-exposed mushrooms can also provide vitamin D.^[2,6] Because fortification varies between products, check the nutrition label rather than assuming that all milk, yoghurt or breakfast cereals contain vitamin D.^[6]

Sunlight exposure

Sunlight can contribute to vitamin D production. However, vitamin D production varies with skin pigmentation, age, clothing, time of day, weather, UVB exposure and the amount of skin exposed.^[2,5,6]

Understanding Vitamin D status

For many people, vitamin D status can be supported through a combination of suitable food choices, safe exposure to sunlight and supplementation when clinically appropriate. People at higher risk should discuss their individual needs with a healthcare professional.^[5,7]

When should you speak to a healthcare professional?

Seek professional advice if you:

• have persistent bone pain, muscle weakness or other symptoms that concern you;
• have osteoporosis, a fragility fracture or another bone-health condition;
• have kidney disease, liver disease, a malabsorption condition or previous bariatric surgery;
• take medicines that may affect vitamin D metabolism;
• are pregnant, breastfeeding or caring for a child with possible deficiency; or
• are considering vitamin D supplements.

A healthcare professional can help you understand whether supplementation may be appropriate, consider potential medicine interactions and advise whether further medical assessment may be needed.^[3,5]

Frequently Asked Questions

What is the main cause of vitamin D deficiency?

There is no single cause. Common reasons include limited sunlight exposure, low dietary intake, malabsorption, older age, certain medicines and conditions affecting the liver or kidneys.^[2,3]

Can you have vitamin D deficiency without symptoms?

Yes. Mild vitamin D deficiency may cause no noticeable symptoms. Symptoms are more likely with significant or prolonged deficiency and may include bone discomfort or muscle weakness.^[3]

How do you know if you have vitamin D deficiency?

When testing is needed, a blood marker measuring serum 25-hydroxyvitamin D, or 25(OH)D may be used. Your doctor can then interpret the results accordingly. ^[5,6]

How long should I stay in the sun for vitamin D?

There may be no universal duration that works for everyone. Vitamin D production depends on skin pigmentation, age, clothing, time of day, weather, UVB exposure and other factors.^[2,5,6]

How do I know if vitamin D3 supplementation is suitable for me?

Vitamin D3, or cholecalciferol, is a form of vitamin D used in supplementation. Whether supplementation is suitable depends on individual circumstances, including dietary intake, health conditions and other factors. A healthcare professional can advise on whether supplementation may be appropriate. ^[4,5]

Need help with vitamin D?

Visit your nearest CARiNG Pharmacy to learn more about vitamin D, including factors that may affect your vitamin D status and when supplementation may be appropriate. Find your nearest CARiNG Pharmacy

References and Citations

Numbered citations in the article correspond to the references below. The original CARiNG/BIG article and its three legacy references are listed first, followed by additional sources used for the update.

[1] CARiNG / BIG Pharmacy. Vitamin D Deficiency: Causes, Symptoms and Solutions. Original article supplied by the content team for this update.

[2] Md Isa Z, Mohd Nordin NR, Mahmud MH, Hashim S. An update on vitamin D deficiency status in Malaysia. Nutrients. 2022;14(3):567. doi:10.3390/nu14030567. Source

[3] Kaur J, Khare S, Sizar O, Givler A. Vitamin D Deficiency. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Updated 2025. Source

[4] Pludowski P, et al. Guidelines for preventing and treating vitamin D deficiency: a 2023 update in Poland. Nutrients. 2023;15(3):695. doi:10.3390/nu15030695. Source

[5] Lee JK, Chee WSS, Foo SH, et al. Vitamin D status and clinical implications in the adult population of Malaysia: a position paper by the Malaysian Vitamin D Special Interest Group. Osteoporosis International. 2023;34:1837-1850. doi:10.1007/s00198-023-06841-4. Source

[6] National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. Source

[7] Demay MB, Pittas AG, Bikle DD, et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2024;109(8):1907-1947. doi:10.1210/clinem/dgae290. Source

[8] CARiNG Pharmacy. SEO & AEO Master Content Pack: Diabetes Prevention, Prediabetes and Diabetes Management. Internal editorial framework used for content structure, visible authorship, question-led headings, FAQ placement and publication governance.