No cold comfort


In the U.S., adults have an average of two to four colds a year and children have an average of six to eight colds. Wouldn't it be nice if zinc could make them vanish?

So far, five published studies have found that zinc gluconate lozenges shorten the duration of colds, while five studies have found no effect, say researchers at the Cleveland Clinic foundation. Now there's number 11--the first to test zinc on children.

Michael Macknin and colleagues enrolled 249 students in their study within 24 hours after they experienced at least two out of nine cold symptoms. Each child was randomly assigned to take either Cold-Eeze lozenges that contained 10 mg of zinc gluconate or a (lookalike but zinc-free) placebo lozenge five times a day (for first- to sixth-graders) or six times a day (for seventh- to twelfth-graders).

The results: Kids who took zinc recovered no sooner than kids who took the placebo. In each group, colds typically lasted nine days.

What explains the failure? Among Macknin's ideas: The dose was lower in children than in adults. It might have been too low. It's also possible that zinc works better in adults because they're more likely to be zinc-deficient than children.

Until more research is done, says Macknin, "it's reasonable for adults to try zinc, given what little else we've got for treating the common cold. They have to figure out whether the benefits outweigh the taste."

J. Amer. Med. Assoc. 279:1962, 1999, 1998

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