Pneumonia is a leading cause of mortality and morbidity in children less than five years old, especially in developing countries. A team of Bangladeshi researchers found that supplements of zinc shortened the time infants needed to stay in hospital to recover from pneumonia.
The study underlines the potential action of zinc on the body's immune system and calls for more research into this mechanism.
Dr Abdullah Brooks and colleagues from the International Centre for Diarrhoeal Disease Research in Bangladesh randomly assigned 270 children between two and 23 months old with severe pneumonia to receive 20 mg zinc per day, or a placebo, in addition to standard hospital antibiotics.
The children given zinc recovered from severe pneumonia an average of one day earlier than did those given placebo, and their average stay in hospital was one day shorter. Since a course of zinc treatment costs only US$0.15, and one day in the study hospital costs US$25, the potential cost savings are substantial, noted the researchers.
"The effects on treatment failure are striking, have significant implications for reduction of antimicrobial resistance by decreasing multiple antibiotic exposures, and could help reduce complications and death in situations where second line drugs are not available," said Dr Brooks.
Zinc has previously been reported to prevent pneumonia, and to prevent and treat diarrhoea. The researchers believe it may boost the body's immune response to infection.
Earlier studies have assessed possible action in the acute phase response to infection, leading to activation of immune defence activity such as macrophages, lymphocytes and natural killer cells.
Another possible effect of zinc is that it may protect the lung from inflammatory states, whereas zinc deficiency might enhance airway inflammation and cellular damage, write the researchers (Lancet issue 22 May, 363: 1683-88).
They add that animal and human studies should be carried out to describe the precise mechanism by which zinc interacts with the acute phase response and its effects on immunity.