Can Zinc Kill the Common Cold? Doctors Skeptical

Feb. 15, 2011— -- The ongoing debate over the role of zinc in combating the common cold was reinvigorated today by a report that suggests the supplement might modestly reduce cold duration and severity -- or maybe even prevent it. But the report, published as a Cochrane Review, raised questions among doctors about the quality of the findings and whether people should start taking zinc for colds.

Drs. Meenu Singh and Rashmi Ranjan Das from the Postgraduate Institute of Medical Education and Research in Chandigarh, India, examined the results from 13 previously therapeutic trials and two preventive trials of zinc in more than 1,300 subjects. Overall, subjects with colds who took zinc were less likely to have symptoms seven days later, and healthy subjects were less likely to get a cold if they took zinc prophylactically.

"This is an important review because many people use zinc products to either treat or prevent common colds," said Dr. William Schaffner, chair of preventive medicine at Vanderbilt University Medical Center in Nashville.

In theory, zinc might prevent the cold virus from attaching to cells in the nose and throat and stop it from replicating in cells that are already infected -- an effect that has been difficult to prove.

All 15 trials reviewed were blinded, meaning the researchers were unaware which subjects were taking zinc. But only six were placebo-controlled, meaning the patients were also unaware of what they were taking -- the gold standard in clinical trials.

Furthermore, zinc lozenges are known to have a bad taste that could be discernable from that of a placebo, Singh and Ranjan Das reported.