Taking zinc acetate lozenges may increase the rate of recovery from the common cold by three fold, new research claims. The analysis of three randomised controlled trials found that on the fifth day, 70 per cent of the patients who took zinc lozenges had recovered compared with 27 per cen of the placebo patients. “Given the strong evidence of efficacy and the low risk of adverse effects, common cold patients may already be encouraged to try zinc acetate lozenges not exceeding 100 mg of elemental zinc per day for treating their colds,” said Harri Hemila from the University of Helsinki in Finland.
The effect of zinc acetate lozenges was not modified by age, sex, race, allergy, smoking, or baseline common cold severity, researchers said. The three-fold increase in the recovery rate from common cold may be widely applicable, they said. While some zinc lozenges have an unpleasant taste, the zinc acetate lozenges used in these three randomised trials did not suffer from such a problem.
The dose of zinc in the three studies was between 80 and 92 milligrammes (mg) per day. Such doses are substantially higher than the recommended daily zinc intake in the US, which is 11 mg/day for men and 8 mg/day for women.
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However, in certain other controlled studies, unrelated to the common cold, zinc has been administered in doses of 100 to 150 mg/day to patients for months with few adverse effects. None of the three analysed zinc lozenge studies observed serious adverse effects of zinc, researchers said. Even though there is strong evidence that properly formulated zinc acetate lozenges can increase the rate of recovery from the common cold by three-fold, many zinc lozenges on the market appear to have either too low doses of zinc or they contain substances that bind zinc ions, such as citric acid.
The findings should not be directly extrapolated to the wide variety of zinc lozenges on the current market, researchers said.