It remains to be seen whether the latest remedy for the common cold is really any better than chicken soup, a hot toddy by the fire and a few days off, but enthusiasts are seizing on the latest evidence that zinc lozenges may reduce cold misery this sneezing season.
There have been eight studies so far on whether zinc can shorten the duration of colds, and the score stands at 4-4.
But the latest study, done by Dr. Michael L. Macknin and colleagues at the Cleveland Clinic and published in the Annals of Internal Medicine, is stirring high hopes, not to mention brisk sales of the little zinc candies.
In fact, the manufacturer of COLD-EEZE, the lozenges studied in Cleveland, can’t keep its zinc gluconate product – roughly $ 5 for a few days’ supply – on the shelves of drug and health food stores.
By Christmas, two more formulations, Fast Dry and ColdFree, based on a slightly different chemical formulation called zinc acetate, are expected to hit the stores.
For all the buzz, nobody knows quite why zinc might help. In the test tube, zinc does seem to stop some viruses from growing. And if you are deficient in zinc, taking some may boost your immune system. (But watch out: too much can do the opposite.)
In the Cleveland study, 100 volunteers, who all had colds and worked at the clinic, were divided into two groups. Half took a fairly high dose (four to eight 13.3 milligram zinc gluconate lozenges a day). The others took a placebo, which was supposed to taste like the real COLD-EEZE.
Neither patients nor doctors knew who got what.
The zinc lozenges “worked remarkably well,” says Macknin, shortening the duration of cold symptoms nearly by half. The folks who sucked on the zinc gluconate candies suffered only 4.4 days of cold symptoms, while the others hung on to their misery for the usual 7.6 days.
And the cold symptoms many people hate most – coughing, headache, hoarseness, nasal congestion, nasal drainage and sore throat – went away the quickest.
The only bothersome side effects, says Macknin, were nausea and the bad taste of the candies. The flavor has since been improved – you still wouldn’t confuse it with Godiva chocolate, but it’s not too bad. Still, some people dropped out of the study because of the taste, and others said it ruined their ability to enjoy food.
Still, Macknin says he and his wife and son now swear by the stuff. His his 11-year-old daughter, though, says she’d “rather be sick.”
Overall, the Cleveland study was “very well done,” says Dr. Ananda Prasad, a professor at Wayne State School of Medicine who studied zinc for years.
“Do I recommend that people take it? Yes, based on that study, it’s worth trying,” he says. And a competing formulation based on zinc acetate “will be better.”
So far, zinc acetate has not been studied in clinical trials, but the inventor of both formulations, George Eby, an entrepreneur in Austin, Texas, is convinced that acetate will prevail because it tastes better.
Eby discovered zinc’s apparent benefits accidentally when his daughter, who had leukemia, started taking zinc and bounced back unusually quickly from a cold. He believes that zinc acetate may actually cure colds, not just reduce their duration.
Not everyone shares his zeal.
Dominick Iacuzio, who heads the influenza and related diseases program at the National Institute of Allergy and Infectious Diseases, cautions that zinc “is controversial,” in part because the data is inconsistent.
And Dr. Jack Gwaltney, a virologist and epidemiologist at the University of Virginia Health Sciences Center, is even more critical.
In studies he did of zinc and cold germs half a dozen years ago, Gwaltney measured both virus and zinc levels in volunteers’ blood – something the Cleveland team did not do – and found that high zinc levels did not make colds go away faster.
This suggests that the zinc in multi-vitamins, helpful as it may be in offsetting zinc deficiency, probably won’t do much for colds.
Furthermore, Gwaltney says, cold viruses grow mostly in the nose, not the throat, and it’s not clear that zinc from lozenges can get to where it might do any good.
In addition, he believes the Cleveland study was flawed because the placebo may not taste enough like the real thing. Macknin counters that only about half of his subjects guessed right about which substance they were taking, so the taste difference could not have been huge.
Jeff Blumberg, associate director of the Tufts University nutrition research center, warns against excessive enthusiasm for zinc, because more is distinctly not better.
The 15 milligrams of zinc found in multi-vitamins is fine, he says. But older people who take zinc as pills start to have immunosuppression at 50 milligrams a day; it probably takes higher doses of zinc from lozenges to induce immunosuppression.
Some research also suggests that large doses of zinc can lower levels of “good” cholesterol, or HDL.
Given all that, perhaps it’s not surprising that two prestigious health newsletters – the University of California at Berkeley’s Wellness Letter and Health News, put out by the Massachusetts Medical Society – view zinc lozenges differently.
The Massachusetts group cautiously endorses the lozenges. But the Berkeley folks say that while COLD-EEZE’s ads tell consumers to “break it to Grandma gently” that they’re going off chicken soup, “We say let Grandma and Grandpa stay at the stove a while longer.”
Lozenges hard to find
Although available as dietary supplements in some health food stores and other retail outlets, zinc remedies for colds can be tough to find because consumer demand is outstripping supply in many areas of the country. In fact, there’s a sign-up list for the lozenges in stores in Chicago, and elsewhere shelves become bare as soon as they are stocked.
So if you’re determined to find the stuff – and remember, these putative cold remedies and the specific claims for their effectiveness have not been reviewed or approved by the FDA – here are some hints.