Zinc lozenges, tablets or syrup taken at the first signs of a cold may shorten the duration of the illness, researchers reported Tuesday. But experts on zinc say there are still many questions about whether the mineral significantly helps with cold treatment.
In the new report, published in the Cochran Library, researchers in India evaluated 15 studies; 13 treatment studies and two studies that focused on zinc to prevent colds. The data were pooled for a total of 1,360 participants ranging in age from 1 to 65. All the participants had good overall health.
Researchers found that people who took zinc within 24 hours of the start of symptoms were over their colds about one day sooner than people who took placebos. The analysis also found that the severity of cold symptoms was somewhat milder among people who took zinc.
But previous studies have not found that zinc helps. One analysis of 14 studies, published in 2007, concluded that many of the studies were too flawed to draw any conclusions. Another meta-analysis—a pooling of studies—published in 2000 in the Cochrane Review, called the body of research inconclusive.
Since the study designs varied widely, it’s impossible to say what doses are optimal, which formulations are best and how long to use the products, said the authors of the new analysis, Meenu Singh and Rashmi R. Das of the Post Graduate Institute of Medical Education and Research in Chandigarh, India.
“I think there is a need for more research so we can get a sense of how well zinc works or if it even does work,” said Dr. Kay Dickersin, a professor of epidemiology at Johns Hopkins Bloomberg School of Public Health and director of the U.S. Cochrane Center. Dickersin was not involved in the research.
In 2009, the Food and Drug Administration warned consumers to stop using three zinc-containing Zicam nasal products after receiving 130 reports about the loss of smell associated with the products. The Cochrane Library analysis did not investigate zinc nasal sprays.
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