As for real scientific evidence on Airborne, the Web page used to provide a link to "clinical results" (no longer there). When Cowan wrote to the company for the information, he received this reply: "The 2003 trial was a small study conducted for what was then a small company. While it yielded very strong results, we feel that the methodology (protocol) employed is not consistent with our current product usage recommendations. Therefore, we no longer make it available to the public." Why? The company CEO, Elise Donahue, told ABC News: "We found that it confused consumers. Consumers are really not scientifically minded enough to be able to understand a clinical study."

ABC News looked into the clinical trial and discovered that it was conducted by GNG Pharmaceutical Services, "a two-man operation started up just to do the Airborne study. There was no clinic, no scientists and no doctors. The man who ran things said he had lots of clinical trial experience. He added that he had a degree from Indiana University, but the school says he never graduated."

In one final lunge at product verisimilitude (dang it, that zesty taste feels like it works), I consulted Harriet Hall, a retired U.S. Air Force flight surgeon and family physician who studies alternative medicine. Hall looked up Airborne's ingredients in the Natural Medicines Comprehensive Database and found no evidence that any of the ingredients prevents colds. Worse, vitamin A is unsafe in doses greater than 10,000 units a day, and Airborne contains 5,000 units per tablet and recommends five pills a day or more. The only positive finding was for vitamin C, for which some evidence indicates that taking high doses may shorten the duration of cold symptoms by one to one and a half days in some patients. But the large amounts needed may cause side effects. "There's more evidence for chicken soup than for Airborne," Hall told me. "In the absence of any credible double-blind studies to support the claims for Airborne, I'll stick to hand washing."