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The essential facts you need to know about Vitamin D

Updated: Jan 20

One of the many nutrients we need to stay healthy is Vitamin D. It is essential for helping the body absorb calcium, which is needed to build strong and healthy bones. More than 40 million adults in the United States have or are at risk of developing osteoporosis (low bone mass which increases bone fragility and the risk of bone fractures). Osteoporosis is most often associated with inadequate calcium intake, but low vitamin D level also contributes to osteoporosis by reducing calcium absorption and causing bone loss. Low levels of vitamin D can result in bone pain, muscle pain and muscle weakness. Vitamin D may play a role in helping our immune system to fight off infections and other illnesses as well.

There is much controversy about other ways vitamin D is thought to help us. Taking vitamin D every day has been shown to reduce the risk of falling in older individuals. Studies suggest that Vitamin D might help prevent cancers such as colon, breast and prostate cancer. Ongoing research suggests that Vitamin D might help prevent and treat diabetes, heart disease, high blood pressure, and multiple sclerosis. However, without additional long-term research, we need to be cautious about taking vitamin D for the prevention of these diseases.

What are the sources of vitamin D?

You can get vitamin D through sun exposure, your diet, and supplements.

Sun exposure

Vitamin D is produced when your skin is exposed to sunshine. The amount of vitamin D that your skin makes depends on factors such as where you live, the season (less sunshine in winter months), the time of day (the sun's rays are most powerful between 10 am and 3 pm), the length of time exposed to the sun, usage of sunscreens, the amount of air pollution and cloudiness. The UV (ultraviolet) light in sunlight causes your skin to make vitamin D.

Food sources (diet)

Consuming foods rich in vitamin D can be very important. Vitamin D content is expressed in International Units. Here are examples of some foods that are high in Vitamin D:

  • Cod liver oil, 1 tablespoon: 1360

  • Swordfish, cooked, 3 ounces: 566

  • Salmon (sockeye) cooked, 3 ounces: 477

  • Tuna, canned in water, drained, 3 ounces: 154

  • Orange juice fortified with vitamin D, 1 cup: 137

  • Milk, vitamin fortified, 1 cup: 115-124

  • Yogurt, fortified with 20% of the daily value of vitamin D, 6 ounces: 80

  • Margarine, fortified, 1 tablespoon: 60

  • Sardines, canned in oil, drained, 2 sardines: 46

  • Liver, beef, cooked, 3 ounces: 42

  • Egg yolk, 1 large: 41

  • Cereal, fortified with 10% of the daily value of vitamin D, 1 cup: 40

  • Cheese, Swiss, 1 ounce: 6

Source: Vitamin D. Health Professionals. Dietary Supplement Fact Sheet. National Institutes of Health. Office of Dietary Supplements. June 24, 2011

Check product labels carefully, as the amount of vitamin D varies when it is added to products such as orange juice, yogurt, and margarine.


Since sun exposure can increase the risk of skin cancer and because there is a limited number of foods that contain vitamin D, getting enough vitamin D can be difficult. Therefore, taking vitamin D supplementation may be needed to prevent vitamin D deficiency.

How much vitamin D is needed?

The amount of vitamin D needed per day in healthy people is shown in the chart below (According to the Institute of Medicine). However, in 2011, The Endocrine Society reported that at least 1,500-2,000 IU/day of supplemental vitamin D might be required in adults, and at least 1,000 IU/day in children and adolescents.

It is important to know that these are general recommendations. Your doctor or pharmacist might recommend higher or lower doses based on your individual needs and your blood levels.

Daily Recommended Vitamin D Intake

Infants 0 - 6 months

Recommended Dietary Allowance (IU/day): 400 Upper Level Intake (IU/day): 1,000

Infants 6 - 12 months

Recommended Dietary Allowance (IU/day): 400 Upper Level Intake (IU/day): 1,500

1 - 3 years old

Recommended Dietary Allowance (IU/day): 600 Upper Level Intake (IU/day): 2,500

4 - 8 years old

Recommended Dietary Allowance (IU/day): 600 Upper Level Intake (IU/day): 3,000

9 - 70 years old

Recommended Dietary Allowance (IU/day): 600 Upper Level Intake (IU/day): 4,000

Over 70 years old

Recommended Dietary Allowance (IU/day): 800 Upper Level Intake (IU/day): 4,000

14 - 50 years old, pregnant/lactating

Recommended Dietary Allowance (IU/day): 600 Upper Level Intake (IU/day): 4,000

Source: Institute of Medicine, released 11/30/2010

It is important to keep in mind that certain medical conditions such as Kidney and liver diseases, cystic fibrosis, crohn’s disease, celiac disease, obesity and gastric bypass surgery may cause low Vitamin D levels.

Other factors that can lead to vitamin D deficiency:

  • Age. The skin's ability to make vitamin D reduces as we get older.

  • Mobility. Homebound individuals or people who are rarely outside (e.g., in nursing homes and other facilities) may not get enough sun exposure as a source of vitamin D.

  • Skin color. Dark-color skin makes less vitamin D than fair-color skin.

  • Human breast milk. A woman's breast milk only contains a small amount of vitamin D. Therefore infants, particularly those who are breastfed exclusively, are at risk for not receiving enough vitamin D.

  • Certain medical conditions. Kidney and liver diseases, cystic fibrosis, crohn’s disease, celiac disease, obesity and gastric bypass surgery may cause low Vitamin D level.

  • Certain medications. Some cholesterol medications, laxatives, steroids, seizure medicines, and weight loss medications may cause low Vit D Always tell your doctor and your pharmacist about the drugs you take.

How often do I need to get my vitamin D level checked?

You need to have your levels checked depending on your medical conditions, risk factors for vitamin D deficiency and certain medications you are taking. Talk to your healthcare provider for guidance.

Can a person ever have too much vitamin D?

Yes. That is why your level needs to be checked in order to adjust your dose accordingly. Symptoms of too much vitamin D include:

  • nausea

  • vomiting

  • itching

  • increased thirst and urination

  • poor appetite

  • constipation

  • weakness

  • weight loss

  • confusion

  • heart rhythm problems

  • kidney damage

Work with your doctor or pharmacist to determine if you need to take a vitamin supplement and, if so, how much to take. Though higher doses are often safely used, too much vitamin D can build up in the body and cause problems. For more information and to see if you need Vitamin D or any other supplements, call Sharzad Green, Pharm.D. at 602-345-1473 or email her at

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