Effect of iron supplementation on incidence of infectious illness in children: systematic review

ObjectiveTo evaluate the effect of iron supplementation on the incidence of infections in children.DesignSystematic review of randomised controlled trials.InterventionsOral or parenteral iron supplementation or fortified formula milk or cereals.OutcomesIncidence of all recorded infectious illnesses, and individual illnesses, including respiratory tract infection, diarrhoea, malaria, other infections, and prevalence of positive smear results for malaria.ResultsThe pooled estimate (random effects model) of the incidence rate ratio (iron v placebo) was 1.02 (95% confidence interval 0.96 to 1.08, P=0.54; P<0.0001 for heterogeneity). The incidence rate difference (iron minus placebo) for all recorded illnesses was 0.06 episodes/child year (−0.06 to 0.18, P=0.34; P<0.0001 for heterogeneity). However, there was an increase in the risk of developing diarrhoea (incidence rate ratio 1.11, 1.01 to 1.23, P=0.04), but this would not have an overall important on public health (incidence rate difference 0.05 episodes/child year, –0.03 to 0.13; P=0.21). The occurrence of other illnesses and positive results on malaria smears (adjusted for positive smears at baseline) were not significantly affected by iron administration. On meta-regression, the statistical heterogeneity could not be explained by the variables studied.ConclusionIron supplementation has no apparent harmful effect on the overall incidence of infectious illnesses in children, though it slightly increases the risk of developing diarrhoea.

What is already known on this topic

Iron supplementation is recommended to prevent iron deficiency, which is a major health problem, especially in the developing countriesConflicting data exist regarding the possibility of an increase in the incidence of infections with iron supplementation, resulting in concern about the safety of this intervention

What this study adds

Iron supplementation has no apparent harmful effect on the overall incidence of infectious illnesses in childrenIron administration increases the risk of developing diarrhoeaFortification of foods may be the safest and most beneficial mode of supplementation in relation to infectious illnesses