Zinc deficiency, marked by severe growth retarda-
tion and arrested sexual development, was first
reported in children and adolescent boys in Egypt,
Iran, and Turkey. Diets in Middle Eastern countries
are typically high infiberand phytates, which inhibit
zinc absorption. Mild zinc deficiency has been found
in vulnerable groups in the United States. Copper
deficiency is rare, but can be caused by excess zinc
from supplementation.
Deficiencies of fluoride, iodine, and selenium
mainly occur due to a low mineral content in either
the water or soil in some areas of the world. Fluoride
deficiency is marked by a high prevalence of dental
caries and is common in geographic regions with
low water-fluoride concentration, which has led to
the fluoridation of water in the United States and
many other parts of the world. Goiter and cretinism
(a condition in which body growth and mental devel-
opment are stunted) have been eliminated by iodiza-
tion of salt in the United States, but still occur in parts
of the world where salt manufacture and distribution
are not regulated. Selenium deficiency due to low lev-
els of the mineral in soil is found in northeast China,
and it has been associated with Keshan disease, a heart
disorder prevalent among people of that area.
Toxicity. Trace minerals can be toxic at higher
intakes, especially for those minerals whose absorp-
tion is not regulated in the body (e.g., selenium and
iodine). Thus, it is important not to habitually exceed
the recommended intake levels. Although toxicity
from dietary sources is unlikely, certain genetic disor-
ders can make people vulnerable to overloads from
food or supplements. One such disorder, hereditary
hemochromatosis, is characterized by iron deposition
in the liver and other tissues due to increased intestinal
iron absorption over many years.
Chronic exposure to trace minerals through cook-
ing or storage containers can result in overloads of
iron, zinc, and copper. Fluorosis, a discoloration of
the teeth, has been reported in regions where the nat-
ural content of fluoride in drinking water is high.
Inhalation of manganese dust over long periods of
time has been found to cause brain damage among
miners and steelworkers in many parts of the world.Resources
BOOKS
Wardlaw, Gordon M. (1999).Perspectives in Nutrition, 4th
edition. Boston: WCB McGraw-Hill.
Whitney, Eleanor N., and Rolfes, Sharon R. (1996).Under-
standing Nutrition, 7th edition. New York: West
Publishing.OTHER
The American Dietetic Association (2002). ‘‘Position of The
American Dietetic Association: Food Fortification and
Dietary Supplements.’’ Available from<http://
http://www.eatright.com>
The Linus Pauling Institute. ‘‘Minerals.’’ Available from
<http://osu.orst.edu/dept/lpi>
United States Department of Agriculture (2002). ‘‘Dietary
Reference Intakes (DRI) and Recommended Dietary
Allowances (RDA).’’ Available from<http://www.nal.
usda.gov/fnic>Sunitha JastiMolybdenum
Definition
Molybdenum is a trace element considered a
micronutrient, meaning a nutrient needed in very
small amounts. It is required by almost all living
organisms and works as a cofactor for enzymes that
carry out important chemical transformations in the
global carbon, nitrogen, and sulfur cycles. Thus,
molybdenum–dependent enzymes are not only
required for the health of people, but also for the
health of ecosystems.Purpose
Molybdenum is an essential trace mineral consid-
ered essential in human nutrition. This is because, as
tiny as the required amounts are, the consequences of
their absence (deficiency) are severe. The active bio-
logical form of molybdenum is known as the molyb-
denum cofactor. It is found in several tissues of the
human body and is required for the activity of
enzymes that are involved in eliminating toxic sub-
stances, including the catabolism of purines, which
produces uric acid, formed primarily in the liver and
excreted by the kidney into the urine. In addition to
being a cofactor of enzymes involved in purine and
pyrimidine detoxification, molybdenum also has ther-
apeutic uses, being used in the treatment of:
Molybdenum deficiency
Molybdenum cofactor deficiency, a disease in which
deficiency of the molybdenum cofactor causes severe
neurological abnormalities, and mental retardation.
Copper poisoning.
Improper carbohydrate metabolism.
Recent research findings suggest that molybde-
num may also have a role in stabilizing the unoccupiedMolybdenum