May 7, 2012 -- Adults who take zinc supplements at the first sign of a cold may shave almost two days off of their sniffling, sneezing, and coughing, a new review study suggests.
That said, the supplements didn't lessen the severity of these symptoms in adults, and had no effects on children, who can catch as many as eight to 10 colds per year. Zinc lozenges or liquids also have their share of side effects, including bad taste and nausea.
"Although oral zinc can impact the duration of [the] common cold in adults, there is not enough evidence to recommend its use in children, and only a weak rationale for its use in adults," says researcher Michelle Science, MD. She is an infectious disease specialist at the Hospital for Sick Children in Toronto, Ontario, Canada.
Exactly how zinc shortens the duration of the common cold is unknown, but it may stop the virus from replicating. The new review included 17 studies comprising a total of 2,121 participants between 1 and 65 years old. Overall, zinc did shorten the duration of the common cold, but only in adults. The higher doses worked better than lower doses.
The findings appear in the Canadian Medical Association Journal.
It is possible that the review did not contain enough studies of children and/or cold symptom severity to draw a firm conclusion.
This is not the final word on zinc. "We need further research and high-quality trials to optimize and maximize the daily doses," Science says.
"Choose a quality zinc product with at least a couple of seals of approvals, including the Good Manufacturing Practices (GMP) seal of approval," he says. This is a way to make sure that the product contains what is stated on its label.
There are still many questions about which form and dose of zinc is best and for whom. "These are the questions we need to answer next," he says.