Function
Zinc functions in many enzymatic reactions and is a component of over 200
enzymes. Besides its role in catalyzing reactions, zinc has a major role in the
structure and function of membranes and in regulating gene expression. in other
processes, zinc assists in the metabolism of carbohydrates and protein and is
involved in the action of hormones such as thymic, insulin, growth and sex
hormones. Zinc is found in many body tissues, including the pancreas, liver,
kidney, lung, muscle, bone, eye, and endocrine glands.
Absorption and Excretion
Zinc is absorbed primarily in the upper jejunum of the small intestine. It
is transported into mucosal cells by a pancreatic zinc-binding ligand and
picked up by albumin for transport to the liver for subsequent storage or
processing.
Other dietary factors may interfere with the absorption of zinc. These include
calcium intake, dietary fiber,
casein, and copper. Gastrointestinal diseases, such as Crohn's
disease, also often affect the absorption of zinc. Zinc is primarily excreted
through the intestinal tract.
Clinical Conditions
Zinc deficient diets can lead to a variety of function difficulties, ranging
from growth retardation to anorexia to lethargy.
- Hypogonadism, a syndrome depicted by dwarfism and decreased function of
the sexual organs, may be seen when there is zinc deficiency during growth
periods of children or adolescents.
- Lack of Zinc may cause a reduction in cell
division,
affecting bone growth.
- Acrodermatitis enteropathica, a heredity disorder characterized by skin
lesions and diarrhea, has been proven to be caused by zinc deficiency.
- Zinc deficiency has been associated with impaired taste and smell, impaired
glucose tolerance, and altered lipid metabolism.
- Zinc deficiency can result in an impairment of the immune system. Specific
immune processes negatively affected by deficiency include thymic hormone
production, function of plasma lymphocytes and neutrophils, and natural
killer cell activity.
Recommended intake
The RDA for zinc is 15 mg for adult males, 12 mg for adult females and children,
and 5 mg for infants.
Food Sources
The best source of zinc is oysters. Beef and other red meats are good sources
of zinc. Whole grains are sources of zinc, though commercial processing
techniques usually slough off the the bran and germ portions of the grain, where
zinc is mostly located. Legumes and nuts are also good sources.
