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.
- 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;279:1962-67.
- Prasad A. Discovery of human zinc deficiency and studies
in an experimental human model. Am J Clin Nutr 1991;53:403-12
- Prasad AS. Zinc in human health: an update. J Trace
Elements Exper Med 1998;11:63-87.
- Sandstead HH. Requirements and toxicity of essential
trace elements, illustrated by zinc and copper. Am J Clin Nutr