Vitamin D

Definition

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

Overview & Functions

In addition to helping the body absorb calcium, vitamin D also helps the body keep the right amount of calcium and phosphorus in the blood.

Food Sources

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)
• Fish
• Oysters
• Fortified cereals
• Margarine

Recommendations

Vitamin D is also known as the "sunshine vitamin" because the body manufactures the vitamin after being exposed to sunshine. Ten to 15 minutes of sunshine 3 times weekly is enough to produce the body's requirement of vitamin D. However, many people living in sunny climates still do not make enough vitamin D and need more from their diet or supplementation.


The Food and Nutrition Board at the Institute of Medicine recommends the following dietary intake for vitamin D as cholecalciferol. (One microgram of cholecalciferol is the same as 40 IU of vitamin D.)
Infants

• 0 - 6 months: 5 micrograms per day (mcg/day)
• 7 - 12 months: 5 mcg/day

Children

• 1 - 13 years: 5 mcg/day

Adolescents and Adults

• Males and Females age 14 to 50: 5 mcg/day
• Males and Females age 51 to 70: 10 mcg/day
• Males and Females age over 70: 15 mcg/day

Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). In general, those over age 50 need higher amounts of vitamin D than younger persons. Ask your health care provider which amount is best for you.

Side Effects

Vitamin D deficiency can lead to osteoporosis in adults or rickets in children.
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. This can reduce their ability to function.

 Kidney stones, vomiting, and muscle weakness may also occur if you have too much vitamin D.

References

Hamrick I, Counts SH. Vitamin and mineral supplements. Wellness and Prevention. December 2008:35(4);729-747.
Rakel D, ed. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007.
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 237.

Vitamin D benefit 

  Vitamin D promotes retention and absorption of calcium and phosphorus, primarily in the bones. Too much vitamin D may have the opposite effect of taking calcium from the bones and depositing it in the heart or lungs, reducing their function

Vitamin D deficit 

  Because vitamin D is essential for the body's utilization of calcium, a deficiency may result in severe loss of calcium and consequently a softening and weakening of bones.