ardent99 writes: A new study (a meta-study?) shows that most of the past studies about the effectiveness of treating colds with zinc are severely flawed. The article finds that despite 20 years of research, the benefits of zinc lozenges as a therapy for the common cold have not been proven. A new study, published in the Sept. 1 issue of Clinical Infectious Diseases, currently available online, reviews the 14 placebo-controlled studies from the past two decades and finds significant fault with 10 of the studies. Of the four remaining studies, three reported no therapeutic effect from zinc lozenge or nasal spray, and one study reported positive results from zinc nasal gel.