| Zinc's Cold-Curing Power
Sniffling again?
Perhaps you should try zinc supplements,
which have been shown in certain trials to cut the duration of a
cold in half. Some researchers have even heralded the element as
the long-sought "silver bullet" for treating the common
cold.
However, does it actually work?
"It depends on who you ask,"
says Dr. Sherif Mossad of the Cleveland Clinic in Ohio. "The
weight of the data is equal in both directions."
Over the past decade, about 14 studies
have been done on the mineral's cold-curing power. According to
Mossad, half have shown that it works and half that it doesn't.
"I don't think the pendulum
is going one way or the other at this time," he says. "Every
year, one or two studies come out because the cold is such a common
problem."
An estimated 62 million people develop
colds in the United States annually, according to the U.S. Centers
for Disease Control and Prevention.
Children have about six to eight
colds a year. In families with children in school, the number of
colds per child can be as high as 12 a year.
Adults average two to four colds
a year. And women, especially those 20 to 30 years of age, have
more colds than men, possibly because of their closer contact with
children, the National Institute of Allergy and Infectious Diseases
says.
While health authorities know a lot
about who gets colds and how frequently, it's much more difficult
to nail down the strain of cold and its symptoms.
Colds are caused by viruses, and
researchers estimate that about 200 of them circulate during the
cold season, which runs from November to April. So determining the
type of cold a person has and what it will do is nearly impossible,
Mossad says.
Another limiting factor to studying
the common cold is the wide variety of symptoms associated with
it, and the subjective evaluation of them. When scientists analyze
the effectiveness of a cold treatment, they depend on patients'
reports about how they feel, which can alter results from study
to study.
"With this illness, you have
mainly subjective responses to the medicine. It's not like you give
a person a blood test and you can see a change," Mossad says.
All that said, however, zinc appears
to be one of the most effective cold treatments available. The element
is usually taken as a lozenge or nasal spray. Scientists believe
it works by either preventing virus cells from reproducing or coating
them so they can't take effect in the body.
Six years ago, Mossad conducted a
randomized, double-blind, placebo-controlled study of zinc's ability
to cure the cold in 100 adults. The patients who received zinc lozenges
six or eight times a day felt relief nearly twice as fast as those
using a placebo lozenge. They saw their symptoms disappear after
an average of 4.4 days, compared to 7.6 days for the placebo group.
The difference was most apparent with coughing and sore throat.
Mossad's best evidence, though, may
be the element's work on his own stuffy head.
"Personally, I use it when I
have a cold and I seem to get better quicker," he says.
Other studies, however, cast doubts.
Four years ago, a prominent trial
of school children showed that zinc did little to assuage their
symptoms. Researchers reported in the Journal of the American
Medical Association that they tested 250 children outside Cleveland,
and found that both those taking zinc lozenges and those taking
a placebo suffered symptoms for an average of nine days.
Moreover a "meta-study"
in the Journal of Nutrition two years ago, which evaluated
11 studies, found that zinc's effectiveness in curing the cold still
hasn't been proven. Many of the positive studies suffered methodological
failings, such as using an ineffective placebo lozenge, researchers
say.
However, the studies concluding zinc
doesn't work also suffer from problems, says Dr. Ananda Prasad,
a professor of medicine at Wayne State University in Detroit. They
failed, he argues, because scientists used lozenges that included
elements besides zinc, because they used doses that were too small,
or because they started treatment more than 24 hours after the cold
began.
"It is really very disturbing.
This is not fair for the public," he says. "Most of the
confusion is that people have been using the wrong preparations
of zinc. Many don't work."
Prasad recommends that people use
simple zinc lozenges without added ingredients or flavorings. Even
though such lozenges have a poor taste and can cause nausea on an
empty stomach, they work much better, he says. His study in 2000
also showed that zinc cut the duration of a cold in half.
"I have no question in my mind
that zinc works. We have used it a lot here at the medical center.
But we always use the right kind, so it works," he says.
For the lozenges to work, they should
be taken every two or three hours, in 12 milligram to 13 milligram
doses, he says.
Since too much zinc can reduce the
copper level in the body, hurting immune response, people shouldn't
take high doses of the element for longer than four days, Prasad
says.
What To Do
For more information about the cold
virus, visit the Common
Cold Centre, run by Cardiff University in South East Wales,
Britain. Or read more about the cold at the National
Library of Medicine.
Reference Source 101
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