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Vitamin D

(Calciferol)

What is Vitamin D and what does it do?

Vitamin D is a nutrient you need for good health. It helps your body absorb calcium, one of the main building blocks for strong bones. Together with calcium, Vitamin D helps protect you from developing osteoporosis, a disease that thins and weakens the bones and makes them more likely to break. Your body needs Vitamin D for other functions too. Your muscles need it to move, and your nerves need it to carry messages between your brain and your body. Your immune system needs Vitamin D to fight off invading bacteria and viruses.

How much Vitamin D do I need?

The amount of Vitamin D you need each day depends on your age.

Average daily recommended amounts are listed below in micrograms (mcg) and International Units (IU).

Life Stage	RDA
Birth to 12 months	10 mcg (400 IU)
Children 1–13 years	15 mcg (600 IU)
Teens 14–18 years	15 mcg (600 IU)
Adults 19–50 years	15 mcg (600 IU)
Adults 51-70 years	15 mcg (600 IU)
Adults 71 years and older	20 mcg (800 IU)
Pregnant teens and women	15 mcg (600 IU)
Breastfeeding teens and women	15 mcg (600 IU)

What foods provide Vitamin D?

Very few foods naturally contain Vitamin D. Fortified foods provide most of the Vitamin D in the diets of people in the United States. Check the Nutrition Facts label for the amount of Vitamin D in a food or beverage.

Almost all of the U.S. milk supply is fortified with about 3 mcg (120 IU) Vitamin D per cup. Many plant-based alternatives such as soy milk, almond milk, and oat milk are similarly fortified, but foods made from milk, like cheese and ice cream, are usually not fortified.

Vitamin D is added to many breakfast cereals and to some brands of orange juice, yogurt, margarine, and other food products.

Fatty fish (like trout, salmon, tuna, and mackerel) and fish liver oils are among the best natural sources of Vitamin D.

Beef liver, egg yolks, and cheese have small amounts of Vitamin D.

Mushrooms provide a little Vitamin D. Some mushrooms have been exposed to ultraviolet light to increase their Vitamin D content.

Can I get Vitamin D from the sun?

Your body makes Vitamin D when your bare skin is exposed to the sun. Most people get at least some Vitamin D this way. However, clouds, smog, old age, and having dark-colored skin reduce the amount of Vitamin D your skin makes. Also, your skin does not make Vitamin D from sunlight through a window.

Ultraviolet radiation from sunshine can cause skin cancer, so it’s important to limit how much time you spend in the sun. Although sunscreen limits Vitamin D production, health experts recommend using sunscreen with a sun protection factor (SPF) of 15 or more when you’re out in the sun for more than a few minutes.

What kinds of Vitamin D dietary supplements are available?

Vitamin D is found in multiVitamin/mineral supplements. It is also available in dietary supplements containing only Vitamin D or Vitamin D combined with a few other nutrients. The two forms of Vitamin D in supplements are D2 (ergocalciferol) and D3 (cholecalciferol). Both forms increase Vitamin D in your blood, but D3 might raise it higher and for longer than D2. Because Vitamin D is fat soluble, it is best absorbed when taken with a meal or snack that includes some fat.

Am I getting enough Vitamin D?

Because you get Vitamin D from food, sunshine, and dietary supplements, one way to know if you’re getting enough is a blood test that measures the amount of Vitamin D in your blood. In the blood, a form of Vitamin D known as 25-hydroxyVitamin D is measured in either nanomoles per liter (nmol/L) or nanograms per milliliter (ng/mL). One nmol/L is equal to 0.4 ng/mL. So, for example, 50 nmol/L is the same as 20 ng/mL.

Levels of 50 nmol/L (20 ng/mL) or above are adequate for most people for bone and overall health.

Levels below 30 nmol/L (12 ng/mL) are too low and might weaken your bones and affect your health.

Levels above 125 nmol/L (50 ng/mL) are too high and might cause health problems.

In the United States, most people have adequate blood levels of Vitamin D. However, almost one out of four people have Vitamin D blood levels that are too low or inadequate for bone and overall health.

Some people are more likely than others to have trouble getting enough Vitamin D:

Breastfed infants. Breast milk alone does not provide infants with an adequate amount of Vitamin D. Breastfed infants should be given a supplement of 10 mcg (400 IU) of Vitamin D each day.

Older adults. As you age, your skin’s ability to make Vitamin D when exposed to sunlight declines.

People who seldom expose their skin to sunshine because they do not go outside or because they keep their body and head covered. Sunscreen also limits the amount of Vitamin D your skin produces.

People with dark skin. The darker your skin, the less Vitamin D you make from sunlight exposure.

People with conditions that limit fat absorption, such as Crohn’s disease, celiac disease, or ulcerative colitis. This is because the Vitamin D you consume is absorbed in the gut along with fat, so if your body has trouble absorbing fat, it will also have trouble absorbing Vitamin D.

People with Obesity or who have undergone gastric bypass surgery. They may need more Vitamin D than other people.

What are the 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.

Symptoms might include:

Fatigue.

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.

What are some effects of Vitamin D on health?

Scientists are studying Vitamin D to better understand how it affects health. Here are several examples of what this research has shown.

Bone health and osteoporosis

Long-term shortages of Vitamin D and calcium cause your bones to become fragile and break more easily. This condition is called osteoporosis. Millions of older women and men have osteoporosis or are at risk of developing this condition. Muscles are also important for healthy bones because they help maintain balance and prevent falls. A shortage of Vitamin D may lead to weak, painful muscles.

Getting recommended amounts of Vitamin D and calcium from foods (and supplements, if needed) will help maintain healthy bones and prevent osteoporosis. Taking Vitamin D and calcium supplements slightly increases bone strength in older adults, but it’s not clear whether they reduce the risk of falling or breaking a bone.
Cancer

Vitamin D does not seem to reduce the risk of developing cancer of the breast, colon, rectum, or lung. It is not clear whether Vitamin D affects the risk of prostate cancer or chance of surviving this cancer. Very high blood levels of Vitamin D may even increase the risk of pancreatic cancer.

Clinical trials suggest that while Vitamin D supplements (with or without calcium) may not affect your risk of getting cancer, they might slightly reduce your risk of dying from this disease. More research is needed to better understand the role that Vitamin D plays in cancer prevention and cancer-related death.
Heart disease

Vitamin D is important for a healthy heart and blood vessels and for normal blood pressure. Some studies show that Vitamin D supplements might help reduce blood cholesterol levels and high blood pressure—two of the main risk factors for heart disease. Other studies show no benefits. If you are overweight or have obesity, taking Vitamin D at doses above 20 mcg (800 IU) per day plus calcium might actually raise your blood pressure. Overall, clinical trials find that Vitamin D supplements do not reduce the risk of developing heart disease or dying from it, even if you have low blood levels of the Vitamin.
Depression

Vitamin D is needed for your brain to function properly. Some studies have found links between low blood levels of Vitamin D and an increased risk of depression. However, clinical trials show that taking Vitamin D supplements does not prevent or ease symptoms of depression.
Multiple sclerosis

People who live near the equator have more sun exposure and higher Vitamin D levels. They also rarely develop multiple sclerosis (MS), a disease that affects the nerves that carry messages from the brain to the rest of the body. Many studies find a link between low blood Vitamin D levels and the risk of developing MS. However, scientists have not actually studied whether Vitamin D supplements can prevent MS. In people who have MS, clinical trials show that taking Vitamin D supplements does not keep symptoms from getting worse or coming back.
Type 2 diabetes

Vitamin D helps your body regulate blood sugar levels. However, clinical trials in people with and without diabetes show that supplemental Vitamin D does not improve blood sugar levels, insulin resistance, or hemoglobin A1c levels (the average level of blood sugar over the past 3 months). Other studies show that Vitamin D supplements don’t stop most people with prediabetes from developing diabetes.
Weight loss

Taking Vitamin D supplements or eating foods that are rich in Vitamin D does not help you lose weight.
Cognitive health

Research shows that people with low levels of Vitamin D in the blood are less able to think and learn, called cognitive decline. But more studies are needed to find out whether Vitamin D supplements may help.

Bone conditions passed through families, called inherited conditions

Vitamin D supplements can be used to help treat inherited conditions that happen when the body can't take in or use Vitamin D. One such condition is familial hypophosphatemia.

Osteomalacia

Vitamin D supplements treat adults with extreme Vitamin D deficiency that results in this softening of the bones.

Psoriasis

Vitamin D treats plaque-type psoriasis in some people. Vitamin D or a cream that has a form of Vitamin D called calcipotriene can be used on the skin.

Rickets

Not having enough Vitamin D in the body can cause this rare condition that weakens bones in children. Taking a Vitamin D supplement can prevent and treat the condition.

Can Vitamin D be harmful?

Yes, getting too much Vitamin D can be harmful. Very high levels of Vitamin D in your blood (greater than 375 nmol/L or 150 ng/mL) can cause nausea, vomiting, muscle weakness, confusion, pain, loss of appetite, dehydration, excessive urination and thirst, and kidney stones. Extremely high levels of Vitamin D can cause kidney failure, irregular heartbeat, and even death. High levels of Vitamin D are almost always caused by consuming excessive amounts of Vitamin D from dietary supplements. You cannot get too much Vitamin D from sunshine because your skin limits the amount of Vitamin D it makes.

The daily upper limits for Vitamin D include intakes from all sources—food, beverages, and supplements—and are listed below in micrograms (mcg) and IU. However, your health care provider might recommend doses above these upper limits for a period of time to treat a Vitamin D deficiency.

Ages	Upper Limit (per day)
Birth to 6 months	25 mcg (1,000 IU)
Infants 7–12 months	38 mcg (1,500 IU)
Children 1–3 years	63 mcg (2,500 IU)
Children 4–8 years	75 mcg (3,000 IU)
Children 9–18 years	100 mcg (4,000 IU)
Adults	100 mcg (4,000 IU)
Pregnant teens and women	100 mcg (4,000 IU)
Breastfeeding teens and women	100 mcg (4,000 IU)

Safety and side effects

Taken in typical doses, Vitamin D is thought to be mainly safe.

But taking too much Vitamin D in the form of supplements can be harmful and even deadly. Taking more than 4,000 IU a day of Vitamin D might cause:

Upset stomach and vomiting.

Weight loss and not wanting to eat.

Muscle weakness.

Not being able to think clearly or quickly.

Heart rhythm issues.

Kidney stones and kidney damage.

Interactions with Medications or Supplements?

Yes, Vitamin D supplements may interact with some medicines. Here are several examples:

Aluminum. Taking Vitamin D and phosphate binders that have aluminum might cause harmful levels of aluminum in people with kidney failure. Phosphate binders treat high blood levels of phosphate in people with longtime kidney disease.

Anticonvulsants. The anticonvulsant medicines phenobarbital (Sezaby) and phenytoin (Dilantin, Phenytek) break down more Vitamin D. This lessens how well the body can take in calcium.

Atorvastatin (Lipitor). Statin medications reduce cholesterol synthesis. Because endogenous Vitamin D is derived from cholesterol, statins may also reduce Vitamin D synthesis [170]. In addition, high intakes of Vitamin D, especially from supplements, might reduce the potency of atorvastatin (Lipitor), lovastatin (Altoprev and Mevacor), and simvastatin (FloLipid and Zocor), because these statins and Vitamin D appear to compete for the same metabolizing enzyme

Calcipotriene (Dovonex, Sorilux). Don't take Vitamin D with this psoriasis medicine. Mixing the two might raise the risk of having too much calcium in the blood, called hypercalcemia.

Cholestyramine (Prevalite, Locholest). Taking Vitamin D with this cholesterol-lowering medicine can lower how much Vitamin D the body takes in.

Cytochrome P450 3A4 substrates, also called CYP3A4 substrates. Use Vitamin D with care if you take a medicine affected by these enzymes. One such medicine is the cholesterol-lowering medicine lovastatin (Altoprev).

Digoxin (Lanoxin). Don't take high doses of Vitamin D with this heart medicine. High doses of Vitamin D can cause too much calcium in the blood, called hypercalcemia. Hypercalcemia raises the risk of fatal heart conditions with digoxin.

Diltiazem (Cardizem, Tiazac, others). Don't take high doses of Vitamin D with this blood pressure medicine. High doses of Vitamin D can cause too much calcium in the blood, called hypercalcemia. Hypercalcemia may keep the medicine from working as it should.

Orlistat (Xenical, Alli). The weight-loss drug, together with a reduced-fat diet, can reduce the absorption of Vitamin D from food and supplements, leading to lower 25(OH)D levels

Thiazide diuretics. Thiazide diuretics (e.g., Hygroton, Lozol, and Microzide) decrease urinary calcium excretion. The combination of these diuretics with Vitamin D supplements (which increase intestinal calcium absorption) might lead to hypercalcemia, especially among older adults and individuals with compromised renal function or hyperparathyroidism.

Steroids. Corticosteroid medications, such as prednisone (Deltasone, Rayos, and Sterapred), are often prescribed to reduce inflammation. These medications can reduce calcium absorption and impair Vitamin D metabolism [174-176]. In the NHANES 2001–2006 survey, 25(OH)D deficiency (less than 25 nmol/L [10 ng/mL]) was more than twice as common among children and adults who reported oral steroid use (11%) than in nonusers

Stimulant laxatives. Long-term use of high doses of stimulant laxatives can lessen how much Vitamin D and calcium the body takes in.

Verapamil (Verelan). Taking high doses of Vitamin D with this blood pressure medicine can cause too much calcium in the blood, called hypercalcemia. High doses of Vitamin D also might keep verapamil from working as well.

Tell your doctor, pharmacist, and other health care providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if the dietary supplements might interact with your medicines. They can also explain whether the medicines you take might interfere with how your body absorbs or uses other nutrients.

Vitamin D and healthful eating

People should get most of their nutrients from food and beverages, according to the federal government’s Dietary Guidelines for Americans. Foods contain Vitamins, minerals, dietary fiber, and other components that benefit health. In some cases, fortified foods and dietary supplements are useful when it is not possible otherwise to meet needs for one or more nutrients (for example, during specific life stages such as pregnancy). For more information about building a healthy dietary pattern.

One Final Note..

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.

The body produces vitamin D via sun exposure. Supplements and a small number of foods also contain vitamin D. The vitamin plays an important role in maintaining the bones and teeth, and may support other bodily functions, too.

Research into the benefits of adequate vitamin D is still ongoing. A vitamin D deficiency can lead to weakened bones and osteoporosis. In excessive doses, vitamin D toxicity can cause hypercalcemia, which can be serious.

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Most recent revision July 12, 2025 08:38:17 AM

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