07/01/10

Facts About Vitamin D

Vitamin D is a group of fat-soluble secosteroids, the two major physiologically relevant forms of which are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is produced in the skin of vertebrates after exposure to ultraviolet B light from the sun or from artificial light sources. While certain foods such as milk, yogurt, margarine, oil spreads, breads, and breakfast cereals can be artificially fortified with Vitamin D, it does occur naturally in a small selection of foods (certain types of fish, fish liver oils, mushrooms). It is also available as a supplement in a pill form.

Adequate intake levels of Vitamin D have been established and depend only on age (i.e., they are the same regardless of gender, pregnancy, or lactation).

• Birth to 13 years, 5 mcg (200 IU)
• 14-18 years, 5 mcg (200 IU)
• 19-50 years, 5 mcg (200 IU)
• 51-70 years, 10 mcg (400 IU)
• 71+ years, 15 mcg (600 IU)

IU – international unit

These recommended levels are based on the assumption that the vitamin is not synthesized by exposure to sunlight.

In the United States, typical diets provide about 100 IU/day. The National Institute of Health has set the safe maximum amount at 2000 IU/day.