Vitamin D

Vitamin D

Cholecalciferol; Vitamin D3; Ergocalciferol; Vitamin D2

Last reviewed: February 8, 2011.

Vitamin D is a fat-soluble vitamin. Fat-soluble vitamins are stored in the body's fatty tissue.


Vitamin D helps the body absorb calcium. Calcium and phosphate are two minerals that are essential for normal bone formation.

Throughout childhood, your body uses these minerals to produce bones. If you do not get enough calcium, or if your body does not absorb enough calcium from your diet, bone production and bone tissues may suffer.

Vitamin D deficiency can lead to osteoporosis in adults or rickets in children.

Food Sources

The body makes vitamin D when the skin is directly exposed to the sun. That is why it is often called the "sunshine" vitamin. Most people meet at least some of their vitamin D needs this way.

Very few foods naturally contain vitamin D. As a result, many foods are fortified with vitamin D. Fortified means that vitamins have been added to the food.

Vitamin D is found in the following foods:

  • Dairy products

    • Cheese

    • Butter

    • Cream

    • Fortified milk (all milk in the U.S. is fortified with vitamin D)

  • Fatty fish (such as tuna, salmon, and mackerel)

  • Oysters

  • Fortified breakfast cereals, margarine, and soy milk (check the Nutrition Fact Panel on the food label)

It can be very hard to get enough vitamin D from food sources alone. As a result, some people may need to take a vitamin D supplement. Vitamin D found in supplements and fortified foods comes in two different forms:

  • D2 (ergocalciferol)

  • D3 (cholecalciferol)

Side Effects

Too much vitamin D can make the intestines absorb too much calcium. This may cause high levels of calcium in the blood. High blood calcium can lead to:

  • Calcium deposits in soft tissues such as the heart and lungs

  • Confusion and disorientation

  • Damage to the kidneys

  • Kidney stones

  • Nausea, vomiting, constipation, poor appetite, weakness, and weight loss


Ten to 15 minutes of sunshine three times weekly is enough to produce the body's requirement of vitamin D. The sun needs to shine on the skin of your face, arms, back, or legs (without sunscreen). Because exposure to sunlight is a risk for skin cancer, you should use sunscreen after a few minutes in the sun.

People who do not live in sunny places may not make enough vitamin D. Skin that is exposed to sunshine indoors through a window will not produce vitamin D. Cloudy days, shade, and having dark-colored skin also cut down on the amount of vitamin D the skin makes.

The Recommended Dietary Allowance (RDA) for vitamins reflects how much of each vitamin most people should get on a daily basis.

  • The RDA for vitamins may be used as goals for each person.

  • How much of each vitamin you need depends on your age and gender. Other factors, such as pregnancy and your health, are also important.

Infants (adequate intake of vitamin D)

  • 0 - 6 months: 400 IU (10 micrograms (mcg) per day)

  • 7 - 12 months: 400 IU (5 mcg/day)


  • 1 - 3 years: 600 IU (15 mcg/day)

  • 4 - 8 years: 600 IU (15 mcg/day)

Older children and adults

  • 9 - 70 years: 600 IU (15 mcg/day)

  • Adults over 70 years: 800 IU (20 mcg/day)

  • Pregnancy and breast-feeding: 600 IU (15 mcg/day)

In general, people over age 50 need higher amounts of vitamin D than younger people. Ask your health care provider which amount is best for you.

Vitamin D toxicity almost always occurs from using too many supplements.

The safe upper limit for vitamin D is:

  • 1,000 to 1,500 IU/day for infants

  • 2,500 to 3,000 IU/day for children 1 - 8 years

  • 4,000 IU/day for children 9 years and older, adults, and pregnant and breast-feeding teens and women

One microgram of cholecalciferol (D3) is the same as 40 IU of vitamin D.

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Flu Fact

Flu Facts:

1. What is the difference between a cold and the flu?

The flu and the common cold are both respiratory illnesses, but they are caused by different viruses. Influenza or "the flu" develops when a flu virus infects your respiratory system, including your nose, throat, bronchial tubes, and possibly the lungs. A cold virus usually infects only your upper respiratory tract: your nose and throat.

The flu usually causes more severe illness than the common cold. Flu can bring on fever, body aches, and exhaustion, symptoms that are rarely caused by simple colds.

2. What are flu symptoms and when is a person contagious?

Primary symptoms of flu are fever, fatigue, aches and pains, chills, and cough. The cough is a bronchial tube irritation and is usually not productive -- you're not coughing up gunk. The flu is usually at its worst for three to four days. The cough may linger longer. Recovery can take seven to 10 days. You may have lingering fatigue for several weeks.

There's one catch with these viruses. About 24 to 72 hours after you're infected, you become contagious. Yet you may not have symptoms, so you don't know you're sick. You feel completely healthy, and go about your daily affairs -- spreading the virus wherever you go.

Stay at home while you've got the flu, and for at least 24 hours after you get over your symptoms. Once you start feeling symptoms, you've already exposed co-workers to the virus -- and you're still contagious. Also, you will recover quicker if you get some rest.

3. What's the best treatment for flu?

There's no single "best" treatment for flu, but there are many ways you can ease symptoms.

Prescription flu drugs can shorten the time you feel sick if taken when your first symptoms appear. They work best when taken within 48 hours of symptoms, but they can also prevent severe disease if taken more than 48 hours after the first symptoms. Over-the-counter cold and flu medicines can offer some relief from fever, aches, stuffy nose, and cough. They don't "cure" the flu, but may help keep you more comfortable.

What can help? Decongestants can help you breathe by shrinking swollen mucous membranes in your nose. Saline nasal sprays can also help open breathing passages. Cough preparations, along with water and fruit juices, can help soothe a cough.

Don’t use over-the-counter cough and cold medicines in children under 4. If your child is between 4 and 6, ask your doctor before giving medicine. It’s safe to use these medicines to help relieve symptoms in kids 6 and older. Never give medicines with aspirin to young adults and children due to the risk of Reye’s syndrome.

It's very important to drink a lot of fluids to keep your body hydrated. This helps loosen mucus. Limit drinks like coffee, tea, and colas with caffeine. They rob your system of fluids. As for eating, follow your appetite. If you're not really hungry, try eating simple foods like white rice or broth.

4. How do prescription flu medications work?

The prescription drugs Tamiflu and Relenza were developed to cut short a bout with flu. They help shorten recovery time by one or two days.

Tamiflu and Relenza work best when taken within 48 hours of the first symptoms. However, clinical studies show the drugs still offer benefits when treatment starts more than 48 hours after symptoms begin.

5. Should I get an antibiotic?

Antibiotics will not help treat the flu. Antibiotics kill bacteria, but they do not kill any viruses, including viruses that cause the flu or colds.

However, the flu can weaken the immune system and open the door for bacterial infections. If your flu starts to get better and then gets worse, you may have a bacterial infection. See a doctor right away. Antibiotic treatment may be necessary.

6. When should I see a doctor?

These symptoms are signs that flu may have developed into something serious like pneumonia. See a doctor if you have any of these symptoms:

· Difficulty breathing

· Persistent fever

· Vomiting or inability to keep fluids down

· Painful swallowing

· Persistent coughing

· Persistent congestion and headaches

7. Why are people so concerned about the flu?

Because the flu virus can infect the lungs, it can cause a serious infection like pneumonia. And that's what worries people. If the flu develops into pneumonia, it may require hospitalization and can even lead to death. People with weak immune systems -- the elderly, pregnant women, infants, and people with chronic health problems -- are at highest risk of flu complications such as pneumonia.

8. Can flu shots cause the flu?

The flu shot is made from killed viruses and cannot "give" you the flu. However, the vaccine can trigger an immune response from your body, so you may have a few mild symptoms, like achy muscles or a low fever.

The nasal flu vaccine, FluMist, is made with weakened live virus. It's recommended as an option only for nonpregnant, healthy people between the ages of 2 and 49.

9. What can I do to prevent the flu?

Flu and cold viruses are transmitted the same way -- through microscopic droplets from an infected person's respiratory system. That person sneezes or coughs, and droplets are sprayed onto any nearby surface -- or person. If they cough or sneeze into their hands (without a tissue), their hands then carry droplets to surfaces they touch. You touch that surface and pick up the virus. If you rub your eyes or nose, you've just infected yourself.

To help protect yourself and prevent spread of cold and flu viruses:

· Wash your hands frequently. Use an alcohol-based gel if you don't have access to water.

· Cough and sneeze into a tissue or into your hands. Wash your hands afterward.

· When you cough, turn your head away from others.

· If you have a sudden sneeze and no tissue, bend your arm and sneeze into it.

· Don't touch your eyes, nose, or mouth. This prevents germs from entering your body.

· Wash any shared surfaces (like phones and keyboards) frequently. Viruses can live on surfaces for several hours.

· Stay away from crowds during cold and flu season.

· Get a flu vaccine every year. Vaccines don't give you 100% protection from the flu, but they're the best way to prevent flu.

· Eat healthy foods to nourish your immune system, such as dark green, red, and yellow vegetables and fruits.

· Get regular exercise. People who exercise may still catch a virus, but they often have less severe symptoms and may recover more quickly.

Also, regular exercise -- aerobics and walking -- may boost the immune system. People who exercise regularly tend to get fewer colds. They may also recover more quickly than people who do not exercise regularly. Check with your doctor before beginning a new exercise program.

10. If I have allergies, am I more likely to get the flu?

No, allergies don't affect susceptibility to the flu. But people with asthma are more likely to have complications, such as pneumonia, when they get the flu. Also at risk of complications are infants under age 6 months, pregnant women, people with suppressed immune systems, people with diabetes, people with lung disease, people with neurologic disease, people with heart disease, and elderly people.

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