Zinc pill for diarrhoea queried

Diarrhoea is a major killer in the developing world

The widespread practice of using zinc and copper supplements to treat diarrhoea may not be effective, research by an Indian team suggests.

A team from Lata Medical Research Foundation assessed the effects of the supplements on 808 children in Nagpur.

The BMC Medicine study found they were no more effective at reducing symptoms than a dummy pill.

However, a World Health Organization expert said many clinical trials over 20 years had supported zinc use.

Diarrhoea is a major killer worldwide, responsible for around 4% of all deaths.

DIARRHOEA Diarrhoea is the passage of three or more loose or liquid stools per day, or more frequently than is normal for the individual Usually a symptom of gastrointestinal infection, caused by a variety of bacterial, viral and parasitic organisms Infection spread through contaminated food or drinking-water, or from person to person due to poor hygiene Severe diarrhoea leads to fluid loss, and may be life-threatening

Zinc is thought to help keep both the intestine and immune system in healthy shape and to aid the absorption of key nutrients and water into the bloodstream.

But zinc deficiency is highly prevalent in children in developing countries and previous research has found that zinc supplements given during diarrhoea reduce its duration and severity.

There is also some evidence that combining zinc and copper supplementation has an even more pronounced effect, although the role of copper is unclear.

The latest study failed to replicate these findings.

Little effect

Lead researcher Dr Archana Patel said: "The expected beneficial effects of zinc supplementation for acute diarrhoea were not observed.

"Therapeutic zinc or zinc and copper supplementation may not have a universal beneficial impact on the duration of acute diarrhoea in children."

The researchers found supplements had little effect on how long diarrhoea lasted, how much diarrhoea the children produced, or how much need they had of oral rehydration salts or intravenous fluids.

The researchers said it was possible that there was something unusual about the children in the study.

The baseline levels of zinc in their bodies may have been unusual, or there may have been something odd about the type of diarrhoea with which they were struggling.

However, the researchers called for a re-examination of all available trial data to try to pin down definitively how much use supplementation may be.

Caution urged

Dr Olivier Fontaine, a diarrhoea expert at the World Health Organization, said: "Evidence on the efficacy of zinc in the management of diarrhoea comes from the results of many clinical trials conducted in hospitals and communities throughout the world over the last 15-20 years.

"Therefore one single negative study cannot dismiss these accumulated evidences that were well reviewed in a couple of meta-analyses."

Dr Fontaine said a recent study from India, based on thousands of children in the state of Haryana, found that zinc supplements cut the number of hospital admissions for diarrhoea by close to 50%.

A similar effect was found in studies conducted in Mali and Pakistan.

Dr Fontaine said a number of factors had been shown to influence the effectiveness of zinc supplementation, such as age of the patient, formulation of the supplement and methods of administration.

He also said it was possible that differences in the zinc status of children in the current trial might account for the negative result.