What is vitamin D deficiency?
Vitamin D deficiency means you don’t have enough vitamin D in your body. It primarily causes issues with your bones and muscles.
Vitamin D is an essential vitamin that your body uses for normal bone development and maintenance. Vitamin D also plays a role in your nervous system, musculoskeletal system and immune system.
You can get vitamin D in a variety of ways, including:
- Sun exposure on your skin (however, people with darker skin and older people may not get enough vitamin D through sunlight. Your geographical location may also prevent adequate vitamin D exposure through sunlight).
- Through the food you eat.
- Through nutritional supplements.
Despite all these methods to get vitamin D, vitamin D deficiency is a common worldwide problem.
Why is vitamin D so important?
Vitamin D is one of many vitamins your body needs to stay healthy. It plays a crucial role in maintaining the balance of calcium in your blood and bones and in building and maintaining bones.
More specifically, you need vitamin D so your body can use calcium and phosphorus to build bones and support healthy tissues.
With chronic and/or severe vitamin D deficiency, a decline in calcium and phosphorus absorption by your intestines leads to hypocalcemia (low calcium levels in your blood). This leads to secondary hyperparathyroidism (overactive parathyroid glands attempting to keep blood calcium levels normal).
Both hypocalcemia and hyperparathyroidism, if severe, can cause symptoms, including muscle weakness and cramps, fatigue and depression.
To try to balance calcium levels in your blood (via secondary hyperparathyroidism), your body takes calcium from your bones, which leads to accelerated bone demineralization (when a bone breaks down faster than it can reform).
This can further result in osteomalacia (soft bones) in adults and rickets in children.
Osteomalacia and osteoporosis put you at an increased risk for bone fractures. Rickets is the same as osteomalacia, but it only affects children. Since a child’s bones are still growing, demineralization causes bowed or bent bones.
Who does vitamin D deficiency affect?
Anyone can have vitamin D deficiency, including infants, children and adults.
Vitamin D deficiency may be more common in people with higher skin melanin content (darker skin) and who wear clothing with extensive skin coverage, particularly in Middle Eastern countries.
How common is vitamin D deficiency?
Vitamin D deficiency is a common global issue. About 1 billion people worldwide have vitamin D deficiency, while 50% of the population has vitamin D insufficiency.
Approximately 35% of adults in the United States have vitamin D deficiency.
Symptoms and Causes
What are the signs and symptoms of vitamin D deficiency?
Severe lack of vitamin D in children causes rickets. Symptoms of rickets include:
- Incorrect growth patterns due to bowed or bent bones.
- Muscle weakness.
- Bone pain.
- Deformities in joints.
This is very rare. Children with a mild vitamin deficiency may just have weak, sore and/or painful muscles.
Lack of vitamin D isn’t quite as obvious in adults. Signs and symptoms might include:
- Bone pain.
- Muscle weakness, muscle aches or muscle cramps.
- Mood changes, like depression.
However, you may have no signs or symptoms of vitamin D deficiency.
What causes vitamin D deficiency?
In general, the two main causes of vitamin D deficiency are:
- Not getting enough vitamin D in your diet and/or through sunlight.
- Your body isn’t properly absorbing or using vitamin D.
There are several specific causes of vitamin D deficiency, including:
- Certain medical conditions.
- Weight loss-surgeries.
- Certain medications.
Several different biological and environmental factors can also put you at a greater risk of developing vitamin D deficiency, such as older age and the amount of melanin (pigment) in your skin.
Medical conditions that can cause vitamin D deficiency
Medical conditions that can cause vitamin D deficiency include:
- Cystic fibrosis, Crohn's disease and celiac disease: These conditions can prevent your intestines from adequately absorbing enough vitamin D through supplements, especially if the condition is untreated.
- Obesity: A body mass index greater than 30 is associated with lower vitamin D levels. Fat cells keep vitamin D isolated so that it’s not released. Obesity often requires taking larger doses of vitamin D supplements to reach and maintain normal levels.
- Kidney disease and liver disease: These conditions reduce the amount of certain enzymes (hepatic enzyme 25–hydroxylase from your liver and 1-alpha-hydroxylase from your kidneys) your body needs to change vitamin D to a form it can use. A lack of either of these enzymes leads to an inadequate level of active vitamin D in your body.
Weight-loss surgeries and vitamin D deficiency
Weight-loss surgeries that reduce the size of your stomach and/or bypass part of your small intestines, such as gastric bypass surgery, make it difficult for your body to absorb sufficient quantities of certain nutrients, vitamins and minerals.
If you’ve had weight-loss surgery, it’s important to see your healthcare provider regularly so they can monitor your vitamin D levels and other nutrient levels. You’ll likely need to take vitamin D supplements and other supplements throughout your life.
Medications that can cause vitamin D deficiency
Certain medications can lower vitamin D levels, including:
- Steroids (such as prednisone).
- Cholesterol-lowering drugs (such as cholestyramine and colestipol).
- Seizure-preventing drugs (such as phenobarbital and phenytoin).
- Rifampin (a tuberculosis drug).
- Orlistat (a weight-loss drug).
Always tell your healthcare provider about your medications and any supplements and/or herbs you take.
Diagnosis and Tests
How is vitamin D deficiency diagnosed?
Healthcare providers don’t usually order routine checks of vitamin D levels, but they might need to check your levels if you have certain medical conditions or risk factors for vitamin D deficiency and/or have symptoms of it.
Your provider can order a blood test to measure your levels of vitamin D. There are two types of tests that they might order, but the most common is the 25-hydroxyvitamin D, known as 25(OH)D for short.
Management and Treatment
How is vitamin D deficiency treated?
The goals of treatment and prevention for vitamin D deficiency are the same: to reach and then maintain an adequate vitamin D level in your body.
While you might consider eating more foods containing vitamin D and getting more sunlight, your healthcare provider will likely recommend taking vitamin D supplements.
Vitamin D comes in two forms: D2 and D3. D2 (ergocalciferol) comes from plants. D3 (cholecalciferol) comes from animals. You need a prescription to get D2. D3, however, is available over the counter. Your body more easily absorbs D3 than D2.
Work with your healthcare provider to find out if you need a vitamin supplement and how much to take, if needed.
Who is most at risk for vitamin D deficiency?
Aside from medical conditions that can lead to vitamin D deficiency, biological and environmental factors that put someone at an increased risk of vitamin D deficiency include:
- Age: Your skin's ability to make vitamin D decreases with age, so people over the age of 65 years are especially at risk for vitamin D deficiency. Infants are also at risk of not receiving enough vitamin D. This is especially true for infants who are only fed breast milk, as it contains only a small amount of vitamin D.
- Skin color: It’s more difficult for dark-colored skin to make vitamin D from sunlight than light-colored skin, so people with darker skin are at a higher risk for vitamin D deficiency.
- Mobility: People who are homebound or rarely go outside (for example, people in nursing homes and other facilities) aren’t able to use sun exposure as a source of vitamin D. Thus, they’re at a higher risk for vitamin D deficiency.
How can I prevent vitamin D deficiency?
The best way to prevent vitamin D deficiency is to ensure you’re getting enough vitamin D in your diet and/or through sun exposure. But be careful about being in the sun for too long without sunscreen. Excessive sun exposure puts you at an increased risk for skin cancer.
The amount of vitamin D you need each day depends on your age. The average daily recommended amounts are listed below in micrograms (mcg) and International Units (IU).
|Age / Life Stage||Recommended Amount|
|Infants up to 12 months old||10 mcg (400 IU)|
|People 1 to 70 years old||15 mcg (600 IU)|
|Adults 71 years and older||20 mcg (800 IU)|
|Pregnant and breastfeeding people||15 mcg (600 IU)|
There are a few foods that naturally have some vitamin D, including:
- Fatty fish such as salmon, tuna and mackerel and sardines.
- Rainbow trout.
- Beef (cow) liver.
- Egg yolks.
- Cod liver oil.
You can also get vitamin D from fortified foods. Be sure to check the nutrition labels to find out if a food has vitamin D. Foods that often have added vitamin D include:
- Cow’s milk and soy, almond and oat milk.
- Breakfast cereals.
- Orange juice.
- Other dairy products, such as yogurt.
Vitamin D is in many multivitamins. There are also vitamin D supplements.
Talk to your healthcare provider if you’re concerned about getting enough vitamin D.
Outlook / Prognosis
What are the possible complications of vitamin D deficiency?
The most serious complications of vitamin D deficiency include:
- Low blood calcium levels (hypocalcemia).
- Low blood phosphate levels (hypophosphatemia).
- Rickets (softening of bones during childhood).
- Osteomalacia (softening of bones in adults).
All of these conditions are treatable. While rickets is a treatable and often curable disease, treating it as soon as possible is important. When not treated, milder cases of rickets can result in long-term bone damage that can keep bones from growing properly. Severe cases that aren’t treated can lead to seizures, heart damage and death.
The good news is that thanks to vitamin D-fortified infant formula and fortified cow’s milk, rickets is very uncommon in the United States.
When should I see my healthcare provider about vitamin D deficiency?
If you’re concerned about whether you’re getting enough vitamin D or if your body is using it properly, talk to your provider.
If you have risk factors for vitamin D deficiency, your provider may recommend checking your vitamin D levels regularly to ensure they’re in a healthy range.
Frequently Asked Questions
Can you ever have too much vitamin D?
Yes. You can get too much vitamin D if you take too many supplements. Interestingly, you can’t get too much vitamin D from the sun. Vitamin D toxicity is rare, but it can lead to hypercalcemia. Symptoms can include:
- Increased thirst and urination.
- Poor appetite.
- Ataxia (impaired balance or coordination).
- Dysarthria (unclear speech).
Don’t take higher-than-recommended doses of vitamin D without first discussing it with your healthcare provider. Also, be cautious about getting large doses of vitamin A along with the D in some fish oils. Vitamin A can also reach toxic levels and can cause serious problems.
A note from Cleveland Clinic
Vitamin D is an important vitamin your body needs to be healthy. If you have risk factors for developing vitamin D deficiency or are experiencing symptoms, be sure to contact your healthcare provider to get a blood test to check your levels.