We already know zinc supplements can help reduce morbidity associated with diarrhoea and pneumonia in young children from the developing world. As both illnesses are often lethal, zinc supplements should also save lives. This had been difficult to prove, however. In the latest attempt, researchers randomised more than 42 000 young children living in Zanzibar, off the coast of East Africa, to receive placebo or a zinc supplement for a mean of 485 days. The supplements had no overall impact on mortality (relative risk of death from all causes 0.93; 95% CI 0.81 to 1.06), except perhaps in children aged over 12 months. Even in this subgroup, the results weren't quite statistically significant (0.82; 0.68 to 1.00). Older boys seemed to benefit most (0.71; 0.54 to 0.93), largely because of reduced deaths from malaria and other infections. Malaria is endemic in Zanzibar.
A linked comment (pp 885-6) says these results are less conclusive than expected. But a beneficial effect on mortality is still likely. It's certainly biologically plausible. Zinc is the second most abundant trace element in the body after iron, and it has a key role in cell division and the maintenance of a healthy immune system.