Last updated: Jan 15, 2009
If a cold hasnt given you a headache already, trying to choose the best supplement just might. The array of products available boggles the mind. Unfortunately, many supplements are long on promises but short on proof. Case in point: echinacea. Its hands-down the most popular herbal cold remedy around, but a recent study in The New England Journal of Medicine found users fared no better than those given a placebo. To identify the supplements that are really worth trying, we turned to some of the nations leading experts, including Jim Duke, former USDA medicinal-plant expert and author of The Green Pharmacy; Mark Blumenthal, founder of the American Botanical Council; and several leading medical specialists around the country. Heres what they suggest.
This herb is just beginning to show up on supplement shelves in the United States, but its widely used in many parts of the world. Last year, researchers in Thailand reviewed four studies that included 433 patients and found that andrographis reduced cold symptoms more effectively than placebos did.
This herb has long been used in traditional Chinese medicine as an immunity-booster. It contains complex sugar molecules called polysaccharides, which some studies show stimulate virus-fighting cells in the immune system. Researchers at the University of Texas and M.D. Anderson Cancer Center have turned up convincing evidence that astragalus boosts immune responses in lab animals, and in human cells in lab dishes. “The findings on immune enhancement are very strong,” Blumenthal says. “And though we dont have good evidence for its effects on colds and flu, theres good reason to think it could help.”
Hippocrates called this herb a “medicine chest,” and new evidence suggests he was right. A study conducted by Israeli scientists showed that a commercially available elderberry extract, called Sambucol, can suppress the growth of influenza viruses in lab dishes. The same research team reported that patients given the extract recovered faster. Though no one knows exactly how elderberry works, its potent antioxidants may enhance immune function.
Honeysuckle and forsythia
Botanist Jim Duke swears by these two common plants, which have a long history in traditional Chinese medicine, as a way to ward off respiratory infections. A variety of lab studies show both contain substances that act against viruses.
This herb has long been used in South African traditional medicine to treat coughs and respiratory ailments, and its beginning to show up in the United States in a product called Umcka. Tests in Europe show it may be especially useful against sore throats and bronchitis. (In a 2003 study, three out of four kids with sore throats who were given the supplement experienced rapid recovery, compared with only one in three offered a sugar pill.) Recent findings suggest pelargonium may speed up the motion of cilia, the tiny hairlike structures in your nasal passages and lungs that capture and eject invading bugs.
These friendly bacteria that turn milk into yogurt can help keep your defenses in top form, says Pat Baird, RD, author of Be Good to Your Gut. Upwards of 70 percent of the immune cells that produce antibodies live in the lining of your digestive tract. Keeping them in peak shape may help you battle colds and flu. In a recent study, German researchers gave 479 volunteers vitamin supplements either with or without probiotics. Those who took the probiotics for at least 3 months reduced the duration of their colds by almost 2 days and the severity of symptoms by about 20 percent.
It became popular thanks to Nobel Prize–winning scientist Linus Pauling, who was sure the vitamin could ward off colds. Eventually, enthusiasm cooled (maybe its no coincidence that Pauling won his Nobels in chemistry and peace, not biology). Most evidence shows vitamin C doesnt prevent colds, says Jane Higdon, a research associate at Linus Pauling Institute at Oregon State University in Corvallis. But, she adds, some studies show that if you take vitamin C at the first sign of a cold, it may shorten the duration by about a day.
By all rights, this mineral should help fight off the sniffles. “Cold viruses gain a foothold in the nose by latching onto uniquely shaped molecules called ICAM-1,” explains Murray Grossan, MD, an ear, nose, and throat specialist at Cedars-Sinai Hospital in Los Angeles. “Zinc binds to the same molecules, which should help prevent cold viruses from attaching.” In fact, a 2003 study at the Cleveland Clinic found that zinc nasal spray shortened the duration of cold symptoms from 6 days to 4.3. Still, other evidence is decidedly mixed. In a review of 14 well-designed studies, 6 showed that zinc helped; the others said it didnt. “So the jury is still out,” says infectious-diseases specialist Sherif Mossad, MD, of the Cleveland Clinic. Theres another thing you should know: Zinc lozenges can deaden your sense of taste. Also, some people using zinc nasal sprays have reported permanently losing their sense of smell, though a connection has not been proven.