Zinc supplementation and stunted infants in Ethiopia: a randomised controlled trial

Background Stunting is highly prevalent in Ethiopia and many other developi ng countries but the reason for it is poorly understood. Zinc is essential for growth but diets in such countries often do not contain zinc in suffici ent quantity or of sufficient bioavailability. Thus zinc deficiency may pla y a major role in stunting. The aim of the study was to investigate whether the low rate of linear growth of apparently healthy breastfed infants in a rural village in Ethiopia could be improved by zinc supplementation. Methods A randomised, double-blind, placebo-controlled trial was done on ap parently healthy breastfed infants aged 6-12 months. 100 non-stunted (lengt h-for-age, Z score <-2) were matched for age and sex with 100 randomly sele cted stunted (>-2) infants. Infants, both stunted and non stunted, were mat ched by sex, age (within 2 months) and recumbent length (within 3 cm) for r andom assignment, to receive a zinc supplement (10 mg zinc per day, as zinc sulphate) or placebo, 6 days a week for 6 months. Anthropometric measureme nts were taken monthly, data on illness and appetite were collected daily, and samples of serum and hair were taken at the end of the intervention for the analysis of zinc. Findings The length of stunted infants increased significantly more (p<0.00 1) when supplemented with zinc (7.0 cm [SE 1.1]) than with placebo (2.8 cm [0.9]); and the effect was greater (p<0.01) than in non-stunted infants (6. 6 [0.9] vs 5.0 [0.8] cm for the zinc and placebo groups respectively, p<0.0 1). Zinc supplementation also increased the weight of stunted children (1.7 3 [0.39] vs 0.95 [0.39] kg for the corresponding placebo group, p<0.001) an d of non-stunted children (1.19 [0.39] vs 1.02 [0.32] kg for the correspond ing placebo group, p<0.05). Zinc supplementation resulted in a markedly low er incidence of anorexia and morbidity from cough, diarrhoea, fever, and vo miting in the stunted children. The total number of these conditions per ch ild was 1.56 and 1.11 in the stunted and non-stunted zinc supplemented chil dren Versus 3.38 and 1.64 in the stunted and non-stunted placebo-treated ch ildren, respectively. At the end of the intervention period, the concentrat ions of zinc in serum and hair of stunted infants, who had not been supplem ented with zinc, were lower than the respective concentrations of zinc in s erum and hair of their non-stunted counterparts. Interpretation Combating zinc deficiency can increase the growth rate of st unted children to that of non-stunted infants in rural Ethiopia. This would appear to be due, at least in part, to reduction in morbidity from infecti on and increased appetite.