"Dr. Mossad doesn't believe the question of zinc's usefulness has been settled. "The bottom line is that it's inconclusive," he says."
WSJ->ACHES & CLAIMS Zinc May Not Zonk Your Cold
With winter coming on, legions of common-cold sufferers may be tempted by pitches for zinc-based nasal sprays and other preparations whose labels claim they have been "clinically proven" to reduce the severity or duration of colds. Many researchers beg to differ.
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Of the 15 clinical studies of zinc-based remedies during the past two decades, only seven have shown beneficial effects. The rest failed to detect any such effects, and scientists are still arguing over the contradictory results.
Since many zinc-based lozenges, nasal sprays and nasal gels sell for roughly $10, consumers may be tempted to play the odds. The preparations, however, can cause side effects such as nasal stinging, bad taste and nausea. Some researchers also believe that in rare cases, nasal gels containing zinc might permanently damage the sense of smell, although that finding is the subject of continuing research.
As a result, it remains unclear whether zinc-based remedies really do much for cold sufferers.
The lack of certainty hasn't stopped the makers of such products from embracing positive studies in their marketing while omitting those that tell a different story. Earlier this year, for instance, Sherif Mossad, a researcher at the Cleveland Clinic Foundation published a study of a zinc-based nasal gel sold by Matrixx Initiatives Inc. of Phoenix. That product, brand-named Zicam, appeared to lessen the severity of colds while reducing their duration by almost 30%, to an average of 4.3 days from six days. Dr. Mossad's study randomly assigned patients to receive either zinc or a placebo and "blinded" the process so that neither patients nor doctors knew which subjects were treated with zinc .
Matrixx, which funded Dr. Mossad's study, now touts that finding, together with the results of an older 2000 study from the Center for Integrative Medicine in Tarzana, Calif., as evidence that Zicam is "clinically proven" to reduce cold severity and duration.
The company doesn't advertise studies that failed to find its product effective. A 2001 study at the Medical University of South Carolina -- also funded by Matrixx -- tested Zicam in patients who were deliberately infected with rhinovirus, the most common cold-causing virus, but saw no impact on the rate of infection or cold severity. Matrixx says that negative study, which was undertaken by the company's previous management, was "flawed from the beginning."
Dr. Mossad doesn't believe the question of zinc's usefulness has been settled. "The bottom line is that it's inconclusive," he says.
Bear that in mind before buying into the zinc-marketing hype.
Updated December 1, 2003 10:23 p.m. |
