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Zinc May Prevent and Shorten Colds


2 Star


Zinc May Prevent and Shorten Colds

Our Review Summary

A review of studies about zinc’s benefits for preventing and treating the common cold was handled in slightly different — but important — ways by three outlets: WebMD, the New York Times and Reuters Health. WebMD hit fewer of our marks because it did not make cost information clear, muddied the waters in its analysis of the evidence and failed to quantify the benefits of zinc in a transparent way. We think it did a nice job explaining the science behind zinc’s effect on colds, and it provided some good details about the possible harms associated with taking zinc.

But Reuters took a much more cautious approach – and appropriately so – with a headline that “Zinc will help your cold, at least a little”.  And the opening sentences:  “may take the edge off the common cold. But not a whole lot.”


Why This Matters

The search for a cure for the common cold is a quest almost as old as medicine, and the researchers involved in this review and in the underlying studies being reviewed were understandably excited about the possibility that zinc might actually prevent colds and cut down on their duration. But, as this story notes at the end, there is still work to be done to determine the right dose and the proper application of zinc to get the most benefit. Stories like this can have the unintended effect of sending droves of people to the drug store to start taking zinc as a daily supplement, even when the jury is still out.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

There was no mention of costs in this story. What the Reuters Health story did was mention the actual costs for the lozenges and also the cost in lost productivity of people calling in sick from colds. Both would have been nice to see in this story.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

This story did quantify the potential benefits, but it did so in a way that was all over the map. At first it says, “When taken within the first 24 hours of symptoms, results from six trials showed that using zinc lozenges or syrup appeared to shorten the duration of a cold by about a day.” But later it says, “‘Usually it takes about eight days for a cold to disappear,’ Prasad says, ‘but with zinc, it cuts down by about 50%.’” And then there is the absolute difference versus relative difference problem. The story never presents the data in absolute terms. “An analysis of two combined studies, representing more than 1,500 people, found about 40% fewer colds in those who were taking zinc supplements to prevent colds compared to those taking a placebo.” Does that mean 10 people had colds in the placebo group, and 6 had them in the zinc group? It would be good information for readers to have because with a number like 1,500, people might leap to the assumption that hundreds of people avoided colds by taking zinc.

Does the story adequately explain/quantify the harms of the intervention?


The story didn’t quantify the potential harms, but did an adequate job mentioning the harms from zinc. This story did an especially good job providing a range of side effects. “Experts stress that more research is needed before the most effective kind of zinc can be determined, and they caution that in high doses — more than 40 milligrams per day — zinc can cause dizziness, headache, drowsiness, increased sweating, loss of muscle coordination, alcohol intolerance, hallucinations, and anemia.”

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The story attempted to give readers a piece-by-piece breakdown of what Cochrane did, but, in the end, it sowed more confusion. First it says, “The review of 15 studies with 1,360 participants was published by the Cochrane group, an international collaboration of researchers that reviews evidence behind therapeutic interventions. It updates a 1999 Cochrane review that found no strong evidence to recommend zinc as a help for colds.” That’s a great start, but it goes on to say, “An analysis of two combined studies, representing more than 1,500 people, found about 40% fewer colds in those who were taking zinc supplements to prevent colds compared to those taking a placebo.” Was this outside of the Cochrane review that only covered 1,360 people? And then the story brings up another study from 2008 “in the Journal of Infectious Diseases, which tested zinc lozenges against placebo in 50 study participants.” Was this one reviewed or is it merely being included here for added context? Unlike the Reuters version, this story does a better job in parsing out the study design, noting that not all of the identified research studies were analyzed for each variable. While the information in the story is correct, the reader is not provided with enough information to appreciate that the researchers parsed the studies reviewed based on the design and data collected. So, while 15 studies were evaluated in total, not all were evaluated for each of the primary and secondary outcomes. The researchers carefully assessed the reliability of their conclusions for both the primary and secondary outcomes. We would have liked to have seen a comment in the story noting that the preventive value of zinc preparations was viewed as less reliable that its ability to shorten the duration of symptoms. This is a great example of providing the right information but in a confused and incomplete manner.

Does the story commit disease-mongering?


No disease-mongering. We thought this story did a good job job explaining how zinc works to fight colds. We recognize that the majority of readers are familiar with the common cold, but we would have liked to have seen some information on the estimated number of cases of the common cold, days out of work or other estimates to put the story into perspective.

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

The story included commentary from “Ananda Prasad, MD, PhD, a professor of internal medicine at Wayne State University School of Medicine in Detroit, who has spent his career researching zinc’s effects on the immune system.”  But, since two of his studies were included in the Cochrane report (something noted by the NY Times story), it’s not truly an independent perspective. And, as noted above, his comments added to some of the confusion in the story.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

The story makes a brief mentoin of only one alternative to zinc: antibiotics. It says, “The review also found that zinc cut the number of days that kids missed school because of being sick and reduced the use of antibiotics by cold sufferers.” What? Most doctors will tell you that antibiotics are ineffective against the common cold, and that they are mainly given as a placebo to make patients feel like they are taking action. Raising the issue of antibiotics without explaining that they don’t really work is a disservice to readers. We would have liked to have seen some comment on the best ways to protect yourself and your family from getting a cold besides zinc products. A few words about hand hygiene and keeping your hands away from your eyes, mouth and nose would have been helpful to the readers.

Does the story establish the availability of the treatment/test/product/procedure?

Not Satisfactory

The story does not make it clear where zinc treatments are available. One could assume that most readers would know, but we think the Reuters Health story did a better job here by actually pointing out that zinc lozenges are sold in most drug stores and even adding the important detail that a specific zinc nasal spray, Zicam, was removed from the market. To its credit however, the story does emphasize that additional research is needed to identify the right zinc preparation and dose.

Does the story establish the true novelty of the approach?


The story makes it clear that zinc has been studied as a possible treatment or preventative measure for the common cold and that this study seems to provide the first significant body of evidence suggesting that zinc has benefits.

Does the story appear to rely solely or largely on a news release?


The story does not rely on a news release.

Total Score: 4 of 10 Satisfactory


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