Claims, Benefits: Prevents or cures the common cold.
Bottom Line: Neither supplement has much in the way of solid science to back it up. And both may have a downside.
Cold Comfort
Two new cold remedies have come on the market, and others will be launched this fall, no doubt. The two newcomers are Zicam, a nasal pump containing zinc, and Airborne, an effervescent tablet with a whole catalog of ingredients. Both are big sellers. And both may have a downside.
Zinc in the nose
Zicam, sold as a homeopathic product, contains zinc gluconate in gel form. A homeopathic remedy should, in theory, have only an undetectable trace of zinc, but Zicam really does contain some. There's a theoretical basis for why zinc might reduce cold symptoms and duration, but the research has been inconclusive.
You can get Zicam in a nasal pump or swab. The idea is to begin using it at the first cold symptom, and continue every four hours until symptoms subside. It claims to reduce the duration of a cold.
Indeed, a study from the Cleveland Clinic Foundation of healthy young people found that the product reduced cold duration from six days to four. Other studies have had less decisive results. One, in the American Journal of Medicine in 2001, found no benefit.
Here's the problem: The FDA is examining reports that the product causes anosmia -- loss of smell. There are lawsuits pending. There is some evidence that applying zinc in the nose can, in rare cases, damage the sense of smell, possibly permanently. Is it worth the risk, just to reduce the duration of a cold by a couple of days? We say no.
Airborne chemistry
Airborne, concocted and marketed by a teacher and touted on the Oprah show, is a tablet you dissolve in water (like Alka-Seltzer). The adult formulation contains high doses of vitamin A (5,000 IU) and vitamin C (1,000 milligrams), as well as vitamin E, magnesium, zinc, selenium and a bouquet of Chinese herbs, including Chinese vitex, isatis root, and others, plus the more familiar-sounding echinacea, ginger, forsythia and honeysuckle.
You're supposed to take the product every three hours at the first sign of a cold, so you could get very large doses of vitamins and minerals. High doses of vitamin A are dangerous for pregnant women, and over the long term could increase the risk of osteoporosis. The safe upper limit is only 10,000 IU -- that's just two Airborne tablets.
There is no truth to the idea that high doses of vitamin C or other vitamins, and in particular vitamin A, will prevent a cold or alleviate symptoms -- and no credible evidence that any of these other ingredients (except possibly zinc) would be useful in any way.
No one knows what the side effects of the herbs might be -- Chinese vitex, for instance, has been linked to increases in blood pressure. Surely, with Airborne's huge sales, the company could afford to sponsor some solid research. It claims that one study has been done, but has not released the results -- and no journal has published it. Should you be a guinea pig for Airborne? Again, we say no. There's no reason to think it's safe or effective.