It turns out that zinc, an essential mineral often touted for its potential ability to cure the common cold, doesn't quite live up to its expectations after all, according to a systematic review of more than 600 studies.
The review, published in the Canadian Medical Association Journal, found that adults who were given a high dosage of zinc experienced a shorter duration of cold symptoms, but also experienced adverse effects, such as a metal taste or nausea. Researchers also found that zinc had no effect on children.
Zinc can inhibit the production of rhinovirus, a common cause of the common cold, so it's often been considered a potential treatment for colds, which affect adults two to four times a year and children eight to ten times per year. However, researchers found that while oral consumption of zinc did in fact reduce adults' symptoms by about one-and-a-half days, the adverse side effects experienced may not make zinc intake worth it. Adults in studies who took zinc reported symptoms of nausea, bad taste, constipation, and even diarrhea.
Also, adults who took zinc experienced no better results after three days compared to placebo groups. "Our findings question the importance of zinc and suggest that any benefit may be outweighed by adverse effects, which were more common among participants given zinc than among controls," researchers said in the study.
As for children, researchers found no benefits to taking zinc to cure a cold in their analysis. Some possible causes for this difference could simply be age-related, or the lower dosage of zinc used in pediatric studies.
The bottom line, researchers say: "Until further evidence becomes available, there is only a weak rationale for physicians to recommend zinc for the treatment of the common cold."
To read the full study, click here.