Zinc Treatment to Under-Five Children: Applications to Improve Child Survival and Reduce Burden of Disease
Larson, Charles P., Roy, S. K., Khan, Azharul Islam, Rahman, Ahmed Shafiqur, Qadri, Firdausi, Journal of Health Population and Nutrition
It is now over a decade since the publication of the landmark articles by Sazawal et al. and Roy et al. which demonstrated the efficacy of orally-administered zinc in the treatment of acute childhood diarrhoea (1,2). Since then, several randomized hospital- and community-based trials have consistently demonstrated the efficacy of zinc treatment for acute or persistent diarrhoea in children aged less than five years (under-five children) (3-6). Pooled analyses of published data demonstrate that zinc reduces the duration and severity of acute diarrhoea and the likelihood of a prolonged episode (7,8). Results from these efficacy trials were then replicated by a community-based, effectiveness trial of zinc treatment for acute childhood diarrhoea carried out in the ICDDR,B rural field site in Matlab. In this trial in which children received daily zinc treatment for each episode of diarrhoea, children in the zinc intervention group had a shorter duration of illness, a reduced likelihood of a repeat episode of diarrhoea, and non-injury mortality. The reduction in mortality was very substantial (50%) (9). This study and several more-cited investigations were carried out by scientists at ICDDR,B who continue to study the effects of zinc on diarrhoeal and other illnesses, most notably childhood pneumonia.
The World Health Organization (WHO) has estimated the global annual burden of mortality attributable to zinc deficiency to be 750,000 deaths (10). It is anticipated that over one-half of these deaths could be averted through the successful application of zinc as a treatment for childhood diarrhoea (11). Given this potential reduction in mortality and the strength of the evidence at hand in support of zinc treatment, the WHO/United Nations Children's Fund (UNICEF) issued, in May 2004, a joint statement on updated guidelines for the management of childhood diarrhoea (12). This includes the recommendation that all under-five children be treated with zinc (20 mg/day if age is 6-59 months and 10 mg/day if age is less than six months) for 10-14 days. This recommendation is now a policy of the Ministry of Health and Family Welfare, Government of Bangladesh, with a slight modification to include children starting at two months of age.
This paper summarizes our understanding of zinc deficiency in children, its relationship with childhood morbidity and mortality, the strategies that have been tested to supplement zinc, and the bene-fits of these interventions. This is followed by a discussion of future research priorities and their applicability to health policy and planning.
ZINC DEFICIENCY IN EARLY CHILDHOOD
Population-based estimates of the occurrence of zinc deficiency in young children are hindered by the lack of an accurate measure of zinc status. Current estimates are based upon one or a combination of zinc-deficiency indicator(s). These include rates of stunting, the amount of zinc in national food supplies, serum zinc levels, and histories of dietary intake.
Despite the limitations in accurately estimating zinc levels, it is now recognized that mild-to-moderate zinc deficiency due to inadequate dietary intake is prevalent in all parts of the world. The higher prevalence of zinc deficiency in developing countries is due primarily to low intake of zinc from animal sources, high dietary phytate content (that limits the bioavailability of zinc), and inadequate food intake (13). A population-level analysis from national food-balance sheets has estimated that 21% of the world population is at risk of inadequate zinc intake; however, the percentages are much higher in least-developed countries (14,15). These children are especially prone to zinc deficiency because of poor dietary quality and increased faecal loss of zinc due to repeated gastrointestinal infections (8). Children with modest levels of chronic zinc deficiency do not manifest any observable clinical signs that would alert clinicians to its presence, thus making it a hidden disorder. …