Researchers from Finland have found that people who take high doses of zinc supplements may experience a 40% reduction in the duration of common colds.
As part of the latest study, published in the Open Respiratory Medicine Journal, a team led by Dr Harri Hemila, from the University of Helskinki, carried out an analysis of 13 trials that examined the effect of zinc lozenges on natural common cold infections.
Three trials used zinc acetate in daily doses of over 75mg, with the average indicating a 42% reduction in the length of colds.
Five studies showed that people who took zinc salts other than acetate in daily doses of over 75mg saw a 20% drop in duration.
However, five studies where zinc doses of less than 75mg were used did not exhibit any effects of zinc.
The studies did not show evidence of any long term negative impact associated with the lozenges.
Researchers said: "Since a large proportion of trial participants have remained without adverse effects, zinc lozenges might be useful for them as a treatment option for the common cold."
For treating the common cold, zinc lozenges are dissolved slowly in the mouth.