Effect of zinc supplementation started during diarrhoea on morbidity and mortality in Bangladeshi children: community randomised trial

EDITOR - We have read the letter by Misbahuddin and Kamaluddin with a
great deal of attention. Since arsenic contamination of the ground water
in Bangladesh is the largest naturally occurring mass poisoning in the
world, we revisited our recommendation to scale up the therapeutic use of
zinc for diarrhoea in view of the findings of Misbahuddin and Kamaluddin
to carefully weigh the benefits and possible risks.

With an average of 7 days of zinc therapy during each episode of
diarrhoea, we demonstrated 24% lower probability of continuing diarrhoea,
15% lower incidence of diarrhoea and a trend suggesting fewer diarrhoea-
related hospitalizations. The reduction in duration of both non-
dysenteric diarrhoea and dysentery was similar. There was a downward
trend of ALRI incidence in the zinc treatment area. The non-injury deaths
in the intervention clusters were only about half those in the comparison
clusters, which was statistically significant.

We were somewhat confused about the findings of Misbahuddin and
Kamaluddin. They reported that oral administration of zinc in adult male
rats at a dose of 1 mg/kg body weight/day for 1 month is effective in the
prevention of arsenic accumulation in different tissues including spleen,
lungs, kidneys, intestine and skin. They further reported that
simultaneous administration of zinc and arsenic increased the accumulation
of arsenic in different tissues, particularly kidneys and spleen. The
authors, however, did not mention the dose and duration of zinc and
arsenic administration in their trial of simultaneous administration. It
is possible that they administered a higher dose of arsenic than the
naturally occurring level in the ground water of Bangladesh and
administered for a longer period than the average 7 days of intake in our
study children. They were not able to explain the reason for the increased
accumulation during simultaneous administration. The additional unresolved
question is how relevant is this finding in an animal model to Bangladeshi
children.

In view of our findings of the significant health benefits including
large reduction of child mortality from the therapeutic use of zinc during
diarrhoea, we reiterate our recommendation to scale up the therapeutic use
of zinc for diarrhoea in Bangladesh and elsewhere. We also recommend that
while scaling up, the relevance of the finding of Misbahuddin and
Kamaluddin is carefully examined.

Competing interests:  
None declared