American Heart Association. 7272 Greenville Avenue, Dal-
las, TX 75231. Telephone: (800) 242-8721. Website:
http://www.americanheart.org
American Dietetic Association. 120 South Riverside
Plaza, Suite 2000, Chicago, Illinois 60606-6995.
Telephone: (800) 877-1600. Website:http://
[http://www.eatright.org](http://www.eatright.org>)
Linus Pauling Institute. Oregon State University, 571
Weniger Hall, Corvallis, OR 97331-6512. Telephone:
(541) 717-5075. Fax: (541) 737-5077. Website:http://
lpi.oregonstate.edu
Vitamin C Foundation. P. O. Box 73172, Houston, TX
- Telephone: (888) 443-3634 or (281) 443-3634.
Website:<www.vitamincfoundation.org/found.htm>
OTHER
Higdon, Jane. ‘‘Vitamin C.’’ Linus Pauling Institute-Oregon
State University, January 31 12, 2006.http://lpi.
oregonstate.edu/infocenter/vitamins/VitaminC
Harvard School of Public Health. ‘‘Vitamins.’’ Harvard
University, November 10, 2006.http://www.hsph.
harvard.edu/nutritionsource/vitamins.html
Maryland Medical Center Programs Center for Integrative
Medicine. ‘‘Vitamin C (Ascorbic Acid).’’ University of
Maryland Medical Center, April 2002.http://www
.umm.edu/altmed/ConsSupplements/VitaminCAscorbic
Acidcs
Medline Plus. ‘‘Vitamin C (Ascorbic Acid).’’ U. S. National
Library of Medicine, August 1, 2006.http://
[http://www.nlm.nih/gov/medlineplus/druginfo/natural/](http://www.nlm.nih/gov/medlineplus/druginfo/natural/)
patient-vitaminc.html
Rajakumar, Kumaravel. ‘‘Scurvy.’’ emedicine.com, August
15, 2006.http://www.emedicine.com/med/topic.htm
Tish Davidson, A.M.Vitamin D
Definition
Vitamin D is a fat-soluble steroid compound that
the body needs to remain healthy. In some ways,
vitamin D is not a true vitamin because the skin can
make vitamin D when exposed to sunlight. However,
if the body does not make enough vitamin D, addi-
tional amounts must be acquired through diet.
Purpose
The main role of vitamin D is to regulate amount
ofcalciumcirculating in the blood. Calcium is a min-
eral acquired through diet that is involved in building
bones, muscle contraction, and nerve impulse trans-
mission. Vitamin D helps regulate the absorption of
calcium from the small intestine. Too little vitamin D
can cause weak, brittle, deformed bones. There is also
evidence that vitamin D plays a role in controlling cell
differentiation and may help to protect the body from
developing some types ofcancer.Description
Vitamin D exists in several forms, two of which are
important to humans. Vitamin D2, called ergocalciferol,
is made by plants. Vitamin D2 can be manufactured
synthetically by irradiating yeast. This type of vitamin
D is most often found indietary supplementsand foods
fortified with vitamin D. Vitamin D3, called cholecalci-
ferol, is made naturally by the skin when it is exposed to
ultraviolet rays in sunlight. Neither vitamin D2 nor D3 is
active in the body. Both must be converted, first in the
liver and then in the kidney, into an active form of
vitamin D (1alpha, 25-dihydroxyvitamin D). Vitamin
D in this topic means the active form of vitamin D.Vitamin D’s role in health
Although Vitamin D has been known to play a
role in bone health for many years, only recently have
researchers begun to explore its effects on cell differ-
entiation and the immune system.
BONE HEALTH.The role of vitamin D and calcium
are closely connected. The body needs calcium to build
bones and teeth, contract muscles, transmit nerveVitamin DTolerable Upper
Age Adequate intake Intake Level
Children 0–12 mos. 200 IU 5 mcg 1,000 IU 25 mcg
Children 1–18 yrs. 200 IU 5 mcg 2,000 IU 50 mcg
Adults 19–50 yrs. 200 IU 5 mcg 2,000 IU 50 mcg
Adults 51–70 yrs. 400 IU 10 mcg 2,000 IU 50 mcg
Adults 71 yrs. 600 IU 15 mcg 2,000 IU 50 mcg
Pregnant women 200 IU 5 mcg 2,000 IU 50 mcg
Breastfeeding women 200 IU 5 mcg 2,000 IU 50 mcg
Food Vitamin D (IU)
Cod liver oil, 1 tbsp. 1,360
Salmon, cooked, 3.5 oz. 360
Mackerel, cooked, 3.5 oz. 345
Tuna, canned in oil, 3 oz. 200
Milk, fortified, 1 cup 100
Orange juice, fortified, 1 cup 100
Cereal, fortified, 1 serving 40
Egg, 1 whole 20
IU International Unit
mcg microgram(Illustration by GGS Information Services/Thomson Gale.)Vitamin D