A recent review of past studies indicate that zinc shortened the duration of the common cold for adults, but the results came at a cost. The duration of the average adult cold is seven days. The U.S. National Institutes of Health estimate that there are over 62 million cases of the common cold annually in the United States, resulting in over 22 million missed days of work. In randomized control trials, adults taking zinc experienced two and a half days less of symptoms of the common cold when compared to participants in a placebo group. Interestingly, zinc had little to no effect on children’s colds in the studies. The benefits of zinc, however, came at a cost. Sixty five percent of the test subjects reported an unpleasant “metallic” taste and 64 percent experienced nausea. There was also no effect on the severity of colds experienced by subjects at day three. The review, published in the Canadian Medical Association Journal also pointed out that researchers are unclear why zinc stops the rhinovirus. They recommended that patients considering taking zinc consult with their doctor first.