The Role of Iron in Brain Development: A Systematic Review.

Samantha McCann, Marta Perapoch Amadó, Sophie E Moore

Journal: Nutrients 2021;12(7):2001

PMID: 32635675

Plain Language Summary

Iron deficiency is the most common vitamin or mineral deficiency worldwide and is particularly common among pregnant women, infants and young children due to high iron demands during periods of rapid growth. Iron plays an important role in the development of the brain, and animal studies suggest that getting enough iron in pregnancy and early childhood is particularly important. The aims of this systematic review were to (i) investigate the relationship between iron status and brain development and (ii) assess whether this relationship differs according to age or type of development (‘domain’). The researchers looked for studies on iron deficiency or iron supplementation in pregnancy and up to 4 years of age. 26 observational studies and 28 intervention studies were included in the review. There was no clear relationship between iron status and developmental outcomes across any of the ages or domains included. Many of the studies were of low quality and there was a wide variation in study design, along with a lack of research on pregnancy and early infancy. The researchers concluded that evidence for the impact of iron deficiency or iron supplementation on early development is inconsistent. Further high-quality research is needed, particularly within pregnancy and early infancy, which has previously been neglected.

Abstract

One-third of children falter in cognitive development by pre-school age. Iron plays an important role in many neurodevelopmental processes, and animal studies suggest that iron sufficiency in pregnancy and infancy is particularly important for neurodevelopment. However, it is not clear whether iron deficiency directly impacts developmental outcomes, and, if so, whether impact differs by timing of exposure or developmental domain. We searched four databases for studies on iron deficiency or iron supplementation in pregnancy, or at 0-6 months, 6-24 months, or 2-4 years of age. All studies included neurodevelopmental assessments in infants or children up to 4 years old. We then qualitatively synthesized the literature. There was no clear relationship between iron status and developmental outcomes across any of the time windows or domains included. We identified a large quantity of low-quality studies, significant heterogeneity in study design and a lack of research focused on pregnancy and early infancy. In summary, despite good mechanistic evidence for the role of iron in brain development, evidence for the impact of iron deficiency or iron supplementation on early development is inconsistent. Further high-quality research is needed, particularly within pregnancy and early infancy, which has previously been neglected.

Address: Department of Women and Children's Health, King's College London, London SE1 7EH, UK.; Medical Research Council Unit, The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, P.O. Box 273, Banjul, The Gambia.; Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK.

DOI: 10.3390/nu12072001

Patient Centred Factor

Antecedents: Iron

Clinical Imbalances

Neurological

Modifiable Lifestyle Factors

Diet

Nutrition Evidence Keywords

Children Iron Pregnancy Cognitive function Neurological Childhood Iron deficiency Brain development Child development

Bioactive Substances

Iron

Link outs

Free resources

Full Text Sources:

Medical:

https://medlineplus.gov/infantandnewbornnutrition....

MeSH Terms: Adult, Anemia, Iron-Deficiency, Brain, Child, Preschool, Dietary Supplements, Female, Humans, Infant, Infant Nutritional Physiological Phenomena, Infant, Newborn, Iron, Iron Deficiencies, Iron, Dietary, Male, Maternal Nutritional Physiological Phenomena, Neurodevelopmental Disorders, Nutritional Status, Pregnancy, Prenatal Care