Sources of Vitamin D
Vitamins D3 and D2 occur naturally in some foods, and both versions of the vitamin are added to certain “fortified” products. Foods provide relatively small doses of D compared with amounts made by the skin in response to UVB light. (IU = international units.)

•  Cod-liver oil (1 tbsp): 1,360 IU D3
•  Cooked tuna, sardines, mackerel or salmon (3–3.5 oz): 200–360 IU D3
•  Shiitake mushrooms (fresh, 3.5 oz): 100 IU D2 (dried, 3.5 oz): 1,600 IU D2
•  Egg yolk: 20 IU D3 or D2
•  Fortified dairy products, orange juice or cereals (one serving): 60–100 IU D3 or D2
•  Full-body exposure to UVB (15 to 20 minutes at midday in summer, fair skin): 10,000 IU D3

Tissues Affected by Vitamin D
The VDR receptor protein (above) is found in many body tissues as well as circulating immune cells, indicating a role for active vitamin D in regulating gene activity in those locations. The list below includes some of the tissues and cells where 1,25D action has been established.

•  Bone
•  Brain
•  Breast
•  Fat
•  Intestine
•  Immune cells
•  Kidneys
•  Liver
•  Nerves
•  Pancreas
•  Parathyroid gland
•  Prostate
•  Skin keratinocytes

D Makes a Difference
Growing evidence suggests that chronically low levels of vitamin D raise a person’s risk for certain major illnesses. Examples of findings based on a population’s blood serum D levels or UV exposure include:

•  30% to 50% higher risk for breast, prostate and colon cancers at serum 25D levels below 20 ng/ml
•  Five times higher risk of ovarian cancer among women living at high latitudes (for example, Norway and Iceland) than women living at equatorial regions
•  77% lower risk for all cancers among Nebraska women age 55 and older taking 1,100 IU of D3 daily over a three-year period compared with a placebo group
•  62% lower risk for multiple sclerosis at serum 25D levels above 40 ng/ml than at 25 ng/ml or less
•  80% lower lifetime risk for autoimmune (type 1) diabetes in Finnish children given 2,000 IU of D3 daily during first year of life

1 Comments

1. 1. linda 10:45 AM 12/25/09

   Most people, including most physicians, don't know their blood vitamin d level. Everyone over the age of 40 should find out their level. Know the number, don't just accept the statement that it's alright. My vitamin d blood level is 65. I take 1500 iu vitamin d every day. I am a registered dietitian with over 20 years cliniocal experience.

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