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.
Because vitamin D can come from sun, food, and supplements, the best measure of one’s vitamin D status is blood levels of a form known as 25-hydroxyvitamin D. Blood levels are described either as nanograms per milliliter (ng/mL) or nanomoles per liter (nmol/L), where 0.4 ng/mL = 1 nmol/L.
Levels below 30 nmol/L (12 ng/mL) are too low for bone or overall health, and levels above 125 nmol/L (50 ng/mL) are probably too high. Levels of 50 nmol/L or above (20 ng/mL or above) are sufficient for most individuals.
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 (10 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.