Exploring the Impact of Iron Supplements on Children Without Iron Deficiency

Review of Iron Supplements in Infants and Young Children

Introduction

A recent review explored the potential link between iron supplements and adverse effects in infants and young children who do not have iron deficiency. Iron is a critical micronutrient, particularly for young children who experience rapid growth and have heightened metabolic demands. Iron deficiency is a widespread issue and can lead to various cognitive and motor developmental challenges in infants. Untreated iron deficiency can result in altered metabolism, as well as severe cognitive and neurophysiological impairments. Although many of these conditions may improve with proper iron supplementation, emerging studies are raising concerns about the adverse effects of iron supplements in certain populations.

Study Overview

A review published in the American Journal of Clinical Nutrition assessed the adverse effects of iron supplementation on developmental defenses and infections in infants and young children by analyzing multiple studies.

Effects of Iron Excess on Growth

Research conducted in Honduras, a region characterized by low socioeconomic status and consequently low iron levels, compared with Sweden, where socioeconomic status and iron levels are high. The findings indicated that iron supplementation effectively improved iron status in Honduran children but had no significant impact on Swedish children, who already had adequate iron levels. Surprisingly, Swedish infants receiving iron supplementation exhibited reduced linear growth despite having hemoglobin concentrations above 110 g/L. These results suggest that while iron supplementation benefits growth in iron-deficient children, it may hinder growth in those who are already iron-replete.

Effects of Iron Excess on Trace Element Status

Trace elements compete for absorption in the small intestine, and an excess of one can negatively affect the absorption of others. Studies indicate that iron supplements may impair the absorption of essential micronutrients such as copper and zinc when taken separately from meals.

Effects of Iron Excess on Morbidity

In iron-replete infants, iron supplements may lead to adverse health outcomes. A study involving Swedish infants with hemoglobin levels exceeding 105 g/L found a higher incidence of diarrhea associated with iron supplementation. Additional research has linked iron supplementation to an increased risk of malaria infection in iron-replete infants. These findings suggest that while iron supplements can help iron-deficient infants avoid infections and gastrointestinal issues, they may pose risks to those who are not iron deficient. This phenomenon may be attributed to iron’s stimulatory effect on pathogens that require iron for growth, as well as changes in gastrointestinal microflora.

Effect of Iron Excess on Cognitive Development

Research has revealed negative effects of iron supplementation on the cognitive development of iron-replete infants who consumed iron-fortified formulas. Impairments were observed in areas such as visual-motor integration, visual perception, and motor coordination. These findings imply that while iron can support cognitive development in iron-deficient infants, it may have the opposite effect in those who are adequately supplied with iron.

Effects of Iron Excess on the Gut Microbiome

Iron plays a significant role in influencing bacterial growth. Studies suggest that iron supplementation in iron-replete infants may alter gut microflora, promoting the growth of pathogenic bacteria.

Conclusion

The cumulative evidence from these studies indicates that iron supplementation in iron-replete infants may lead to negative outcomes, including reduced growth, increased illness, impaired absorption of other micronutrients, shifts in gut microbiota toward more pathogenic strains, and cognitive and developmental deficiencies. These concerning effects underscore the need for larger studies to better understand the underlying mechanisms involved. Additionally, they highlight the importance of assessing baseline iron status prior to administering iron supplements to children.

Written by

Nima Makhdami, M.D.

Reference

Lönnerdal, B. (2017). Excess iron intake as a factor in growth, infections, and development of infants and young children. The American Journal of Clinical Nutrition, ajcn156042.