Excess iron intake as a factor in growth, infections, and development of infants and young children

Abstract

The provision of iron via supplementation or the fortification of foods has been shown to be effective in preventing and treating iron deficiency and iron deficiency anemia in infants and young children. However, iron is a pro-oxidative element and can have negative effects on biological systems even at moderate amounts. An increasing number of studies have reported adverse effects of iron that was given to infants and young-children populations who initially were iron replete. These effects include decreased growth (both linear growth and weight), increased illness (usually diarrhea), interactions with other trace elements such as copper and zinc, altered gut microbiota to more pathogenic bacteria, increased inflammatory markers, and impaired cognitive and motor development. If these results can be confirmed by larger and well-controlled studies, it may have considerable programmatic implications (e.g., the necessity to screen for iron status before interventions to exclude iron-replete individuals). A lack of understanding of the mechanisms underlying these adverse outcomes limits our ability to modify present supplementation and fortification strategies. This review summarizes studies on the adverse effects of iron on various outcomes; suggests possible mechanisms that may explain these observations, which are usually made in clinical studies and intervention trials; and gives examples from animal models and in vitro studies. With a better understanding of these mechanisms, it may be possible to find novel ways of providing iron in a form that causes fewer or no adverse effects even when subjects are iron replete. However, it is apparent that our understanding is limited, and research in this area is urgently needed.Am J Clin Nutr 2017;106(Suppl):1681S-7S.

Iron status and inherited haemoglobin disorders modify the effects of micronutrient powders on linear growth and morbidity among young Lao children in a double-blind randomised trial

“…This latter study also included a cohort of children in Honduras, where this same effect of reduced length gain was found only in children who were initially nonanaemic, which is similar to the present results. The overall impact of supplementary Fe on young children's growth has been inconsistent (38) , and the underlying mechanisms of reduced growth observed with Fe supplementation in some studies are unknown (39) , but supplementary Fe may be more likely to result in adverse effects on growth among non-anaemic or Fe-replete children (37,40,41) . Among the growth outcomes, only final wasting prevalence was modified by IHbD.…”

Vulnerability of adult hippocampus to toxicity after postnatal exposure of nursing male albino rats to iron overload : Histomorphometric and ultrastructural study

“…It is broadly recommended as a prophylactic measure against iron deficiency anemia, which commonly occurs in infancy especially breast-fed infants because of insufficient iron supply in breast milk. However, growing evidences reported iron overload as a consequence of iron fortification [7] .…”

Assessment of Risk Factors for Iron Deficiency Anemia in Infants and Young Children: A Case–Control Study

“…33 Unfortunately, excess iron intake in iron-replete infants is associated with decreased growth, increased infectious diseases risk, and altered homeostasis of other microelements. 34 Exclusive breastfeeding for 6 months with introduction of nutritious complementary foods thereafter is seen as the most important measure to reduce the risk of nutritional anemias. 2 Nevertheless, majority of study participants were introduced to complementary foods earlier than recommended by WHO.…”