Tell me about...
Zinc
What is
Zinc?
Zinc is an important trace mineral. A bluish-white, metallic
element, it is second only to iron in terms of its concentration
in the body.
Why do
we need it?
Zinc plays an important role in the proper functioning of
the body's immune system. Several studies have shown that
zinc lozenges shorten the duration of cold symptoms in adults.
Zinc is required for a number of activities related to cell
reproduction and wound healing. It has also been linked to
improvements in one's senses of smell and taste, and is involved
in the body's ability to metabolize carbohydrates for energy
consumption.
How much
should I take?
According to the National Academy of Sciences, the recommended
daily allowance (RDA) for zinc is as follows:
- Adult men: 15 milligrams/day
- Adult women: 12 milligrams/day
- Children (7-10 years): 10 milligrams/day
- Infants: 5 milligrams/day
- Pregnant and lactating women: 19 milligrams/day
Higher levels of zinc are usually reserved for treating certain
health conditions. Such supplementation should take place
only under the supervision of a health care professional.
What are
some good sources of zinc?
High-protein foods such as chicken, beef, eggs and tofu contain
high amounts of zinc. The dark meat of a chicken has a higher
zinc content than the light meat. Other good sources include
peanuts, peanut butter and legumes (such as beans, peas and
lentils).
What can happen if I don't get enough
zinc?
Symptoms associated with zinc deficiency include slow or
impaired growth, decreased resistance to infections, slower
wound healing and loss of hair. The senses of smell and taste
can also be impaired by low zinc levels.
What can
happen if I take too much?
Taking large amounts of zinc supplements (70 or more times
the recommended daily allowance) may cause diarrhea, nausea,
abdominal cramps and vomiting within 3-10 hours after taking
the supplements. These symptoms can be reversed or diminished
by discontinuing supplement use.
It should also be known that zinc inhibits copper absorption,
which can lead in some cases to anemia and lower levels of
HDL ("good") cholesterol. Fortunately, most zinc
supplements also contain extra amounts of copper to prevent
inhibition from occurring.
Other Resources :
The
More You Know About Minerals
The
More You Know About Nutrition
References
• National Academy
of Sciences. Recommended Daily Allowances, 10th ed.,
1989.
• Macknin ML, Piedmonte M, Calendine C, et al. Zinc gluconate
lozenges for treating the common cold in children. A randomized
controlled trial. JAMA 1998;279:196267.
• Prasad A. Discovery of human zinc deficiency and studies
in an experimental human model. Am J Clin Nutr 1991;53:40312
[review].
• Prasad AS. Zinc in human health: an update. J Trace
Elements Exper Med 1998;11:6387.
• Sandstead HH. Requirements and toxicity of essential
trace elements, illustrated by zinc and copper. Am J Clin
Nutr 1995;61(suppl):621S24S [review].
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