Do coldbuster remedies work?

According to a 1998 study reported in the Journal of the American Medical Association, between 15 and 18 percent of Americans swallow, steep, or suck on roots, tinctures, and other alternative "immunostimulants" when they're ailing. Ostensibly, these nonpharmaceutical remedies boost the production of infection-fighting cells. Are they worth a damn? A growing body of clinical research indicates that some natural medicines do work—but, cautions James Dillard, a sports medicine physician at the Columbia University College of Physicians and Surgeons and coauthor of Alternative Medicine for Dummies, "Not every herbal remedy is equal to every other herbal remedy." Herewith, Dillard's scorecard on four commonly used elixirs.

ECHINACEA
The most popular herbal remedy, and for good reason. Says Dillard, "A wealth of research supports the notion that echinacea is an effective immunostimulant." Take it as a capsule or dissolve a tincture in water at the first hint of a cold. Dillard notes that echinacea is a mild mitogen that tends to up the production of immunity-boosting T cells.

ASTRAGALUS
The sweet-tasting black root of the feather-leafed plant Astragalus membranaceus, boiled to make medicinal tea or soup, isn't about to best echinacea anytime soon. "Astragalus is a proven immunostimulant," says Dillard, "but there is not a wealth of research on its effect on upper-respiratory infections." While University of Texas researchers successfully used astragalus to boost the function of cancer patients' immune cells in the lab, there are no published clinical trials supporting its cold-fighting reputation.

ZINC
According to a study by the Cleveland Clinic Foundation, zinc reduced the duration of cold symptoms. Moreover, subjects taking zinc felt better three days earlier than those on a placebo. But in Dillard's view, seven other oft-cited studies of zinc's cold-fighting properties don't add up to much, largely because he questions their methodology. "For me, it's a wash," he says.

VITAMIN C
The results are mixed. Several research studies have indicated that the classic flu-buster is merely a placebo, but others have shown that vitamin C may help shorten a cold's cycle by one day. Perhaps, like all remedies, it's a question of timing. "If you feel like you are starting to fight off something, hit early," advises Dillard. And hit hard. —JAMES GLAVE