A randomized controlled trial of chelated zinc for prevention of the common cold in Thai school children

Abstract

Background: The common cold is responsible for the largest proportion of school and work absenteeism and is a huge economic burden. None of the currently available interventions is clearly effective for prevention or treatment.

Objective: To assess the efficacy of 15-mg chelated zinc (zinc bis-glycinate) given once a day for 3 months during the winter season to healthy school children aged 8–13 years to prevent symptoms of the common cold.

Methods: In a double-blind randomized controlled trial, zinc bis-glycinate 15 mg or matching placebo once a day for 3 months was administered to healthy school children aged 8–13 years. Primary outcomes were any symptom of cold (fever, cough, rhinorrhoea) during the study period, and secondary outcomes were vomiting, diarrhoea, use of antibiotics, school absence for any reason, school absence because of a cold and duration of all symptoms.

Results: Of 50 children in each group, 42 (84%) in the zinc group and 41 (82%) in the placebo group (P = 1·00) developed at least one symptom of a cold. There was no difference in the incidence of fever, cough, rhinorrhoea, school absence and school absence related to the common cold compared with children in the placebo group. However, duration of cough [median (IQR) 1·0 (0·0–6·0) vs 6·0 (0·0–13·3) days], rhinorrhoea [median (IQR) 2·0 (0·0–7·0) vs 5·5 (1·0–15·3) days] and the frequency of having two or more symptoms of the common cold [median (IQR) 0·0 (0·0–1·0) vs 1·0 (0·0–5·3) days] were reduced significantly in the intervention group (P<0·01).

Conclusions: Zinc bis-glycinate given in a dose of 15 mg once a day for 3 months failed to reduce the incidence of the common cold in 8 to 13-year-old school children, but decreased the number of days on which children suffered from cough, rhinorrhoea and the likelihood of having two or more symptoms of the common cold.

Keywords:

• Chelated zinc
• Common cold
• Cough
• Fever
• School children
• Zinc bis-glycinate

The study was supported by grants from the Faculty of Medicine, Srinakharinwirot University, Thailand. The authors thank Qualimed (Bangkok, Thailand) for supplying the zinc bis-glycinate and placebo. The manufacturer had no role in the planning, execution or analysis of the study.