Zinc
A review in the Open Respiratory Medicine Journal (2011, Vol. 5, pp. 51-58) concluded that zinc lozenges may shorten the duration of common cold episodes by up to 40%.
Data from five trials using total daily zinc doses of less than 75 mg found no effect, but data from three trials using zinc acetate in daily doses of over 75 mg indicated that the mineral may reduce the duration of the cold by 42%.
Date from five trials using zinc salts – other than acetate – in daily doses of over 75 mg found a reduction in cold duration by 20%.
Similar results were obtained from a 2011 Cochrane review, but only if taken within a day of the onset of cold symptoms.
The total economic impact of cold-related work loss is estimated to exceed $20 billion USD per year (Cochrane review). As a result, Americans spend around $2.9 billion on over-the-counter drugs (and another $400 million on prescription medicines) for symptomatic relief of cold.
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