Diseases & Conditions

Vitamin D Deficiency

Vitamin D deficiency is a condition characterized by low levels of vitamin D in the body. Vitamin D is essential for normal bone development and maintenance, and also plays an important role in the nervous, musculoskeletal, and immune systems.

Vitamin D deficiency primarily affects the health of bones and muscles. We get vitamin D from various sources, including sunlight, food and supplements. However, vitamin D deficiency remains a common problem, particularly in the Middle East.

The importance of vitamin D

Vitamin D plays an important role in maintaining calcium balance in our blood and bones and contributes to bone building and maintenance. Insufficient levels of vitamin D can lead to hypocalcemia (low calcium levels) and hyperparathyroidism, which causes parathyroid glands to become overactive as they try and maintain normal calcium levels in the blood.

Both these conditions can cause symptoms such as muscle weakness, cramps, depression and fatigue.

Chronic deficiency causes the body to withdraw calcium from our bones, which leads to bone demineralization and increases the risk of osteomalacia (soft bones) in adults and rickets (bent or bowed bones) in children.

Who is affected by vitamin D deficiency?

Vitamin D deficiency can affect anyone, from babies to adults. It is more common in people with a higher skin melanin (the pigment in the skin that gives it color) content and in those who cover their skin more with clothing.

What are the symptoms of vitamin D deficiency?

In children, vitamin D deficiency causes muscles to become weak or sore. In severe cases, it can lead to rickets. The symptoms of rickets are bent or bowed bones, bone pain, muscle weakness and deformed joints.

In adults, vitamin D deficiency causes symptoms such as:

  • Muscle cramps
  • Fatigue
  • Mood changes
  • Bone pain.

What causes vitamin D deficiency?

The main causes of vitamin D deficiency are a lack of vitamin D in the diet or through sunlight, and the body not absorbing or using it properly.

Other causes of vitamin D deficiency include:

Medical conditions:

  • Cystic fibrosis, Crohn's disease, and celiac disease can all prevent your intestines from absorbing enough vitamin D.
  • Obesity: Fat cells isolate vitamin D and it isn’t released properly, meaning higher amounts are needed to maintain normal levels.
  • Liver disease and kidney disease: These reduce the amount of an enzyme that is needed to absorb vitamin D.

Weight-loss surgery: If part of the stomach or small intestine is bypassed in weight-loss surgery, it means the body cannot absorb as much vitamin D as it needs.

Medication: Certain drugs including laxatives, steroids, weight-loss drugs and cholesterol lowering medication, can lower vitamin D levels.

How is vitamin D deficiency diagnosed?

Routine checks for vitamin D levels are not standard but may be necessary for those with risk factors or symptoms. Blood tests, particularly the 25-hydroxyvitamin D test, can determine vitamin D levels.

How is vitamin D deficiency treated?

Treating vitamin D deficiency aims to reach and maintain adequate vitamin D levels. While increasing dietary intake and sunlight exposure are recommended, your doctor may also recommend vitamin D supplements.

There are two types of vitamin D supplements:

  • D2 which comes from plants. A prescription is needed for D2.
  • D3 comes from animals and is available to buy in a pharmacy. It is more readily absorbed than D2.

What are the risk factors for vitamin D deficiency?

As well as medical conditions, other factors can increase the risk of vitamin D deficiency. These include:

  • Age: Our skin makes less vitamin D as we age.
  • Skin color: Those with darker skin are more at risk as they make less vitamin D.
  • Mobility: People who are unable to go outside as much due to mobility issues are at an increased risk of vitamin D deficiency, due to reduced sun exposure.

How can vitamin D deficiency be prevented?

Increasing vitamin D intake through the foods you eat, and sun exposure are the best ways to prevent deficiency. Always be careful not to overexpose your skin to the sun’s harmful rays and use sunscreen if you are outside for prolonged periods of time.


Understanding vitamin D deficiency and preventive measures are crucial for maintaining overall health. If you are at risk, talk to the Family Medicine Program team at Cleveland Clinic Abu Dhabi.

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© Copyright 2017 Cleveland Clinic Abu Dhabi. All rights reserved.

This information is provided by Cleveland Clinic Abu Dhabi, part of Mubadala Healthcare, and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition.

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