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Pour Your Zinc Down the Sink?
Jury's Still Out on Whether Zinc Works For Colds
By Jeanie Davis
Nov 16, 2001 -- Getting your medicine cabinet ready for the onset of cold season? A recent study raises more questions about zinc products -- whether they will halt those nasty colds or not.
"It's still a cloudy subject," says study author Edward A. Belongia, MD, an epidemiologist at Marshfield Medical Research Foundation in Marshfield, Wis. His paper appeared in a recent issue of The American Journal of Medicine.
In his study of 160 people -- all in the first 24-hour throes of cold symptoms -- Belongia tested the effects of a zinc sulfate nasal spray. Half got the zinc spray; half got a placebo spray. All were asked to use their spray four times a day. "It's about as much as you can ask of someone," he says.
After 14 days, the zinc spray "pretty much had no effect at all," he tells WebMD. "We did find a very, very minimal benefit on day one, but not on any other day. And there was no significant effect on duration of cold symptoms. Both groups got over their colds at the same time."
Don't think this means Zicam -- a zinc gel spray on store shelves -- will or won't work, says Belongia. "This is not the same formulation as Zicam; that is a zinc gluconate gel. And Zicam has a higher concentration of zinc than the product we tested," he says. "You can't draw any conclusions from our study whether Zicam works or not."
Only one study of Zicam has been published, and it left out important details that have kept other researchers guessing, says Belongia. Combined with studies of zinc lozenges -- which have been conflicting -- it all says that zinc might work -- under the right circumstances, he says. And the theory behind sprays or gels makes sense, because they deliver the zinc to the lining of the nose, where the common cold virus replicates, he tells WebMD.
"Maybe a higher dose that stays on for longer time would work," he says.
Albert Monto, MD, professor of epidemiology in the school of public health at the University of Michigan at Ann Arbor, has studied numerous cold treatments.
"This study is not going to put the issue of zinc to bed," he tells WebMD. "It's just like with echinacea; there are believers.
"Research into zinc has been going on for many, many years," Monto says. "There have been all sorts of reports using various zinc salts, different preparations, various concentrations." The problem is, the compound and the delivery method have to be just right in order to work.
With all the inconsistencies in all the studies, "if there is an effect [from zinc], then it is a small effect," he says.
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