Catch a summer cold and you know you're in for about a week of feeling congested and crummy. But what if you could get rid of that cold a little sooner? A new study published online May 7 in the Canadian Medical Association Journal suggests adults who take zinc supplements within a few days of the onset of symptoms may shorten a cold by nearly two days. However, the study also showed that zinc might cause unpleasant symptoms, including nausea and bad taste.
The issue of whether zinc could reduce the duration of the common cold has been studied for a few decades. This analysis reviewed the evidence published since the mid-80s and in the end, after evaluating 17 randomized controlled trials of oral zinc preparations for the common cold, the Canadian researchers ended up with more questions than answers. The trials included 2,121 children and adults with naturally acquired and induced colds, who were given placebos, or compounds of zinc-containing lozenges, tablets, or syrup. Zinc appeared to reduce the length of colds in adults, but it did not make a difference in children. The researchers suggested that lower doses of zinc sulfate, delivered less frequently, in syrup may explain the lack of effect in children.
"Certain zinc compounds, such as zinc acetate, and treatment regimens with higher doses, seem to have the greatest benefit," says Michelle Science, M.D., lead author of the study and staff physician, Division of Infectious Diseases at The Hospital for Sick Children in Toronto. But Science and her colleagues were unable to pinpoint appropriate zinc formulations, doses, and adverse effects among various age groups. "Personally I don't use zinc for colds, because I believe the side effects outweigh the benefits," said Dr. Science. She and the other researchers reported no conflict of interests with industry.
Ananda Prasad, M.D., Ph.D., an expert on zinc and Distinguished Professor of Hematology and Oncology at Wayne State University School of Medicine, has a different perspective. Prasad explains that zinc, a mineral absorbed when we eat protein in animals, fish and nuts, is critical to our immune system and cell growth. Taken as an oral supplement, zinc may behave as an antiviral agent, preventing rhinoviruses--responsible for most colds--from attaching to the lining of the nose and throat.
What should you do if you're about to travel, have a big event approaching, or simply want to get rid of your cold sooner? "I don't see a downside to people who are healthy, and especially those who travel, taking zinc for 3-5 days as long as they don't take too much," says Joseph Mosquera, MD, medical adviser to Consumer Reports and a board certified physician trained in integrative-medicine. Mosquera warns patients away from intranasal zinc-gluconate, which according to a 2006 Consumer Reports investigation and 2009 FDA findings may cause a loss of smell. He recommends choosing zinc products with proper USP verification and dosing.
See our guide to zinc