Harvard Health Publications

Zinc for the common cold? Not for me

Posted By Patrick J. Skerrett On February 17, 2011

Media channels are atwitter with the news that zinc can beat the common cold. CBS News, the L.A. Times, the Huffington Post, and hundreds of others are treating a quiet research report as big news that will have a life-changing effect. After reading the report and doing a little digging into the dark side of zinc, I’m not rushing out to stock up on zinc lozenges or syrup.

The latest hubbub about zinc was sparked by a report from the Cochrane Collaboration. This global network of scientists, patients, and others evaluates the evidence on hundreds of different treatments. In the latest review, on zinc for the common cold, researchers Meenu Singh and Rashmi R. Das pooled the results of 13 studies that tested zinc for treating colds. By their analysis, taking zinc within 24 hours of first noticing the signs of a cold could shorten the cold by one day. They also found that taking zinc made colds a bit less severe.

Sounds good so far. But instead of saying, “Hey, take zinc if you have a cold,” the researchers concluded like this: “People taking zinc lozenges (not syrup or tablet form) are more likely to experience adverse events, including bad taste and nausea. As there are no studies in participants in whom common cold symptoms might be troublesome (for example, those with underlying chronic illness, immunodeficiency, asthma, etc.), the use of zinc currently cannot be recommended for them. Given the variability in the populations studied (no studies from low- or middle-income countries), dose, formulation and duration of zinc used in the included studies, more research is needed to address these variabilities and determine the optimal duration of treatment as well as the dosage and formulations of zinc that will produce clinical benefits without increasing adverse effects [italics mine], before making a general recommendation for zinc in treatment of the common cold.”

Not exactly a ringing endorsement.

Zinc isn’t something to mess around with. Two years ago, the FDA warned everyone to stop using zinc-containing nasal sprays to fight colds because these sprays had been linked to more than 100 cases of loss of smell. The Institute of Medicine set the tolerable upper limit for zinc at 40 milligrams a day for adults, less for teens and children. The tolerable upper limit is the highest daily intake “likely to pose no risk of adverse health effects for almost all individuals.” If you follow the directions on zinc-based cold remedies, you’ll get more than the tolerable upper limit.

The glowing media reports are sure to spark the next cold rush as supplement makers crank up their zinc output. I’m going to ignore it. I don’t like the taste of zinc lozenges, and don’t think it’s worth sucking on them for several day to knock a day off a cold.

At the first sign of a cold, I’m headed to the kitchen to make chicken noodle soup.

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