• Vitamin D is classified as a fat-soluble vitamin, but it really is a prohormone. It is essential for normal growth and development; important for formation of normal bones and teeth; influences absorption and metabolism of phosphorus and calcium. Vitamin D is toxic in large quantities, especially if taken for long periods of time.

DRI (RDA or AI for Adults)

• Under age 51: 200 IU.

• Ages 51-70: 400 IU. Over 70: 600 IU.

• Pregnancy/Lactation: 200 IU.

• 1 mcg of cholecalciferol = 40 IU. For example: 5 mcg = 200 IU.

MAJOR SOURCES

• Vitamin D3: cod liver oil, herring oil, pacific oysters, salmon oil, mackerel, most fish.

• Vitamin D2 is plant derived (a special yeast is irradiated with UV light).

• Regular sunlight on un-sunblocked skin can provide the RDA.

MAINTENANCE/THERAPEUTIC RANGE

• 400 IU to 5,000 IU. (High range for limited time to increase bone density.)

POSSIBLE THERAPEUTIC APPLICATIONS

• Cancer

• Multiple sclerosis

• Osteoporosis

COMMENTS

• For light-skinned people, exposing the face and arms to bright sunlight for ten minutes or so, several days per week, is enough to maintain moderately healthy levels of vitamin D. (Exposure time for light-skinned people living in mid- to lower latitudes, late spring to early fall, late morning to early afternoon.) However, because of vitamin D’s anticancer properties, some health professionals are now recommending daily intakes of 1,000 IU or more. Also, new research shows that, for osteoporosis, more emphasis should be placed on vitamin D, and less on calcium.

CAUTIONS

• Consult with your health practitioner before taking doses much greater than 1,000 IU.