Suck on this: zinc lozenges don't lessen cold symptoms
Last Updated: Friday, August 3, 2007 | 12:27 PM ET
CBC News
Zinc lozenges have long been a mainstay in fighting the common cold.
But a review of 20 years of research into the effectiveness of zinc as a therapy for cold symptoms has turned up some bad news.
Canadians spend more than $300 million a year on over-the-counter cold remedies.
(CBC) "The best scientific evidence available indicates that zinc lozenges are not effective in treating colds," said Jack Gwaltney, one of the study's authors and professor emeritus of internal medicine at the University of Virginia School of Medicine, in a release.
A new study to be published in the Sept. 1 issue of Clinical Infectious Disease finds that most studies of zinc lozenges are flawed.
Researchers sorted through 105 studies of zinc and the common cold. From these, they extracted 14 randomized, placebo-controlled studies, the kind of study that might provide the strongest evidence for or against zinc's usefulness in relieving cold symptoms. They then checked each study for 11 features of experimental design that were required to produce valid results.
Ten of the studies lacked a quantifiable hypothesis or had sample sizes too small to produce statistically valid findings, the researchers said. Of the four that were conducted according to sound scientific principles, three studies found that zinc lozenges and nasal spray were ineffective.
One study on zinc nasal gel did report positive effects.
For that reason, Gwaltney suggests further studies of nasal gels be conducted.
It has been estimated that adults suffer two to five colds per year, says the Canadian Centre for Occupational Health and Safety.
And treating colds is big business. Canadians spend more than $300 million a year on over-the-counter cold remedies, according to the College of Family Physicians of Canada. |
