In 10 different clinical studies, zinc was able to prevent or reduce the symptoms of the common cold in 50% of the cases. It is not unthinkable, however, that too small amounts of zinc or some kind of reduced absorption may have played a role in some of the studies.
In order to gain more clarity of this, a group of scientists from Detroit, Michigan, perfomed a double-blind, placebo-controlled trial with zinc acetate.
They studied the immune defence in 30 women and 18 men and they tested them for various infections, including HIV. All trial subjects started taking either zinc lozenges or placebo (ineffective) lozenges within the first 24 hours after the appearance of cold symptoms. The lozenges were to be taken every other or third hour during the day for as long as the symptoms were present and the trial subjects were not to take any other type of medication for their symptoms.
The study showed that the persons who had taken placebo tablets had symptoms for an average of 8 days which is almost twice as long as in the ones who had taken zinc (4.5 days). Furthermore, the symptoms in the zinc group were lighter than in the placebo group.
Actually, the scientists do not know precisely why zinc supplements have this beneficial effect on the common cold. They believe that it promotes the production of certain immunostimulatory substances.
The zinc tablets that were used in the study contained 43 mg. of zinc acetate, which equals 12.8 mg. of pure zinc.
