High Doses of Zinc Found to Reduce Common Cold Duration

Daily use of lozenges with more than 75 mg zinc acetate reduces cold duration by 42 percent

WEDNESDAY, Aug. 3 (HealthDay News) -- In individuals with natural common cold infections, use of lozenges containing a daily zinc dose of over 75 mg significantly reduces cold symptoms, but use of a daily total of less than 75 mg shows no effect, according to a meta-analysis published online June 23 in the Open Respiratory Medicine Journal.

Harri Hemila, M.D., Ph.D, from the University of Helsinki in Finland, reviewed available literature to examine the relationship between total daily dose of zinc from lozenges and its effect on common cold duration in patients who had natural common cold infections. A total of 13 placebo-controlled comparisons were analyzed separately for low and high zinc dose by two methods: combining P-values of the studies by the Fisher method, and pooling the results of all the studies using the inverse-variance method.

The investigator found there was no effect on cold symptoms in five studies using total daily zinc dose of less than 75 mg. Pooled analysis of three studies using over 75 mg daily doses of acetate zinc showed a 42 percent reduction in the duration of colds. The pooled analysis of five studies using zinc salts other than acetate in daily doses of over 75 mg showed a 20 percent reduction in duration of colds.

"The zinc lozenge effect on common cold duration is heterogeneous so that benefit is observed with high doses of zinc but not with low doses," the authors write.

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