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Herbal preparation to prevent respiratory tract infections

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Ten years ago annual expenditure on herbal medicines was over 2 billion dollars in the USA and over 40 million pounds in the UK. Since then sales have grown by 10–15% per year. A study in Israel (

) of a preparation containing echinacea, propolis, and vitamin C has shown a remarkable protective effect against respiratory tract symptoms in children.

The preparation (Chizukit) contains 50 mg of echinacea (E purpurea upper parts, E angustifolia roots), 50 mg of propolis, and 10 mg of vitamin C in one millilitre. Echinacea is considered to be an immune stimulant and in vitro and animal studies have shown effects on cytokines, macrophages, and natural killer cells. Propolis is found in beehives and is said to have antiinfective properties. Vitamin C has immunomodulatory properties.

In a double-blind trial 430 children aged 1–5 years were recruited from 10 primary care community clinics and randomised to take either Chizukit or placebo for 12 weeks during the winter of 1999–2000. Parents recorded respiratory symptoms on diary cards and follow up visits were conducted at 4, 8, and 12 weeks. Any upper respiratory tract infections were confirmed by study physicians at the time of occurrence. There was a large dropout rate (55 from the treatment group and 44 controls) largely because of unpleasant taste. Among children remaining in the trial the total number of episodes of respiratory illness was 138 in 160 children (Chizukit) and 308 in 168 children (placebo). The total number of illness days was 423 vs 1040. The mean duration of episodes was 1.6 vs 2.9 days. Reductions of 50–68% were seen in diagnoses of upper respiratory tract infection, acute otitis media, pneumonia, and tonsillopharyngitis.

In an analysis of the paper (ibid: 222–4) methodological faults are highlighted. These include the large dropout rate resulting in a change from the intended intention-to-treat to per-protocol analysis, the lack of demographic data comparing treatment and control groups, and the lack of clearly defined diagnostic criteria. Nevertheless, their final comment is that the magnitude of the results is compelling and warrants further research.

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