much thyroid hormone, a serious condition called
hyperthyroidism. Other conditions can also cause the
thyroid gland to produce too much or too little hor-
mone. A urine test is used to determine if an individual
is iodine deficient, and blood tests can check for other
thyroid function problems.Precautions
Pregnant and breastfeeding women must be espe-
cially careful to get enough iodine, since iodine defi-
ciency has its greatest effect on the fetus and newborn.
Vegans, who do not eat animal products and depend
onsoyfor much of theirprotein, are at higher risk of
iodine deficiency than the general population.Interactions
Amiodarone (Cordarone) a drug used to prevent
irregular heart rhythms, contains enough iodine that it
may affect thyroid function.
Some foods contain substances called goitrogens
that interfere with the body’s ability to absorb or use
iodine. These include broccoli, cabbage, cauliflower,
and brussel sprouts. Other foods that contain goitro-
gens are canola oil, soybeans, turnips, peanuts, and
cassava. These foods should not cause iodine defi-
ciency unless they are tine mainstay of a very limited
diet.
Seleniumdeficiency amplifies the effects of iodine
deficiency.Vitamin Adeficiency may amplify iodine
deficiency.Complications
Complications of iodine deficiency are discussed
above. Iodine excess rarely is caused by diet, although
an excess of thyroid hormones may result from other
causes.Parental concerns
In developed countries, parents should have few
concerns about their healthy children getting enough
iodine, so long as they use iodized table salt.Resources
BOOKS
Food and Nutrition Board, Institute of Medicine.Dietary
Reference Intakes for Vitamin A, Vitamin K, Arsenic,
Boron, Chromium, Cooper, Iodine, Iron, Manganese,
Molybdenum, Nickel, Silicon, Vanadium, and Zinc.
Washington, DC: National Academy Press, 2001, pp.
162-177. http://books.nap.edu/books/0309072794/
html/Lieberman, Shari and Nancy Bruning.The Real Vitamin and
Mineral Book: The Definitive Guide to Designing Your
Personal Supplement Program,4th ed. New York:
Avery, 2007.
Pressman, Alan H. and Sheila Buff.The Complete Idiot’s
Guide to Vitamins and Minerals,3rd ed. Indianapolis,
IN: Alpha Books, 2007.
ORGANIZATIONS
International Council for the Control of Iodine Deficiency
Disorders.<http://indorgs.virginia.edu/iccidd>
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>
OTHER
Higdon, Jane. ‘‘Iodine.’’ Linus Pauling Institute-Oregon State
University, April 11, 2003.<http://lpi.oregonstate.edu/
infocenter/minerals/iodine>
International Council for the Control of Iodine Deficiency
Disorders. ‘‘Iodine Deficiency Disorder (IDD).’’
August 18, 2005.<http://indorgs.virginia.edu/iccidd/
aboutidd.htm>
Lee, Stephanie L. ‘‘Iodine Deficiency.’’ eMedicine.com, July
27, 2006.<http://www.emedicine.com/med/
topic.1187htm>
Medline Plus. ‘‘Iodine.’’ U. S. National Library of Medicine,
November 1, 2006.<http://www.nlm.nih/gov/medline
plus/druginfo/natural/patient-iodine.html>
Mercer, L. Preston. ‘‘Iodine.’’ American Society for Nutrition,
2006.<http://jn.nutrition.org/nutinfo>
Northwesternutrition ‘‘Nutrition Fact Sheet: Iodine.’’
Northwestern University, September 21, 2006.<http://
http://www.feinberg.northwestern.edu/nutrition/factsheets/
iodine.html>Helen DavidsonIrish dietseeNorthern European diet
Iron
Definition
Iron (Fe) is a metal essential to almost all bacteria,
plants, and animals. In humans, iron is a compnent of
the red pigment hemoglobin that gives red blood cells
their color and affects the transport of oxygen
throughout the body, conversion of nutrients into
energy, production of new deoxyribonucleic acid
(DNA, genetic material), and regulation of cell growth
and cell differentiation. Without iron, life on Earth
would not exist. Humans must acquire all the iron
they need from diet.Iron