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Zinc: a Cure for the Common Cold?

The Cochrane Library today published a systematic review of trials examining a link between zinc supplementation and the reduction of symptoms of the common cold. Focusing on a carefully selected group of high-quality clinical trials, the Review analysed the results in order to assess the effect of zinc on common cold symptoms. Read on for a summary, or click here for access to the full 61-page report: http://www.thecochranelibrary.com/view/0/index.html.

Adults suffer from 2-4 colds each year and 40% of time off work is due to colds. As yet, there is no proven method of treating the common cold, but there has been interest in the therapeutic use of zinc since 1984.

The review examined fifteen randomised double-blind placebo controlled trials in high income countries and the participants were healthy individuals of both genders and aged from 1-65. Thirteen of the trials were therapeutic and zinc or the placebo was administered within 3 days of cold symptoms manifesting themselves. It was given in the form of lozenges, capsules or syrup at 1.5-2 hourly intervals over a 6-hour period over 5days. Two of the trials explored the prevention of colds through zinc supplementation over a period of five months. The doses ranged from 30-160mg per day.

The Review concluded that there is evidence to suggest that zinc can have a therapeutic effect on the common cold by reducing the duration and severity of symptoms in healthy people when administered within 24 hours of the onset of symptoms. When supplemented for a minimum of five months, as a preventative approach, it can reduce the incidence of colds and subsequent absenteeism from school or work.

However, further studies are required to establish an effective and safe dosage, as the doses varied across the different trials, and caution is required with regard to potential zinc toxicity. Further research is also advised into individuals with a history of cold and respiratory conditions, and into lower income populations, as these were excluded from the trials examined in the Cochrane Review.