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

Nutrients. 2020;12(7)
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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.

Lifestyle medicine

Fundamental Clinical Imbalances : Neurological
Patient Centred Factors : Antecedents/Iron
Environmental Inputs : Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Not applicable
Bioactive Substances : Iron

Methodological quality

Jadad score : Not applicable
Allocation concealment : Not applicable
Publication Type : Journal Article ; Systematic Review

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