(Excerpted from LANCET 2004; 363 :1683-1688 . Accessed on www.thelancet.com)
Dr Santosh Singh

Pneumonia is a leading cause of morbidity and mortality in children less than 5 years old responsible for about 20% deaths. Two-thirds of these deaths happen during infancy, and more than 90% are in developing countries.

Zinc is reported to prevent pneumonia, and to prevent and treat diarrhoea. It might act in the acute phase response to infection, helping to boost the body’s immune response through a defense cascade

A double blind randomized placebo controlled clinical trial was carried out in hospitalised children suffering from pneumonia, between 2 and 23 months of age, to see whether zinc, along with antibiotics, would improve the outcome of severe pneumonia. Children were then randomised to receive either 20 mg elemental zinc per day as acetate or placebo until they were discharged from hospital

Therapy for pneumonia was initially with parenteral antibiotics including ampicillin and gentamicin or ceftriaxone, if needed. This was followed by oral antibiotics once the patients improved.

Baseline serum zinc concentrations were 10.1 micromol/L (SD1 .1) and 10.0 micromol/L (1.0) for zinc and placebo groups, respectively. At the end of the study, both groups had higher serum zinc concentration than at baseline 14.5 micromol/L (p<0.0001) for zinc and 11.2 micromol/L for placebo group (p<0.0001). The difference between the zinc and placebo groups discharge zinc concentrations was also significant (p<0.0001).

Children aged 12 months or older resolved their respiratory illness earlier than younger infants for all measured outcomes. Each severe pneumonia indicator improved in zinc supplemented children compared with those receiving placebo. There were shorter durations of chest indrawing, respiratory rate more than 50 per min, and hypoxia, leading to shorter overall duration of severe pneumonia, as well as total hospital stay. These resulted in a mean difference of 4 (95% CI 4.2-4.9) versus 5 (4.5-5.5) days of severe pneumonia, and 5 (4.8-5.5) versus 6 (5.1-6.1) days of hospitalisation for the zinc and placebo groups, respectively

This study has demonstrated clinically and statistically significant reductions in recovery time from severe pneumonia and overall hospital stay in children less than 2 years old given zinc with standard antimicrobial therapy. The zinc supplement was safe and well tolerated in children as young as 2 months old.

The reductions in the duration of severe pneumonia and its components and overall hospitalization might be mediated by the role of zinc in the acute phase response, mediated by cytokines during acute infection. Thus, by maximizing tissue bioavailability of zinc in these children, they may have had a more robust immune response and recovered more quickly.

Another possible effect of zinc is on the extent of inflammation and its resolution rate surrounding infection. Zinc supplementation might protect the lung from inflammatory states, whereas zinc deficiency might enhance airway inflammation and cellular damage. In the presence of zinc, animals had decreased inflammation of other organ systems and increased bacterial inhibition and cellular regeneration. Thus, zinc may reduce inflammation, and lower airway obstruction, in supplemented children and contribute to faster inflammation resolution time, manifested by shorter duration of chest indrawing, high respiratory rate, and hypoxia. The benefit from zinc seems to increase after 100 h of illness. This lag period in effect onset has been reported elsewhere, and might be inherent in the mechanism of the zinc effect.

Zinc might boost the acute phase and protective immune responses irrespective of a child’s zinc status, in which case even zinc-replete children would derive a benefit.


Last updated on 19-12-2006