Childhood cognitive function

Overview

Iron is the primary supplement studied for childhood cognitive function, with nine indexed trials. Oral iron appears to improve learning, memory, and attention mainly in children and teens with low iron levels or anemia, with higher doses over several weeks showing clearer cognitive gains.

Benefits are less consistent in non-anemic children, and once-weekly iron dosing may not help and could harm some cognitive measures in those without deficiency. Most positive outcomes were seen after months of supplementation in iron-deficient groups. See the evidence reviews below for dose and population details.

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Iron	★★★★★	Medium

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Consider purchase★★★★★

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Effect SizeMediumEvidenceHighTrustVery High

Evidence Review

Taking iron supplements by mouth can help improve thinking and memory skills in children and teens who have low iron levels.
Studies show that higher doses for several weeks help with learning and memory, while lower doses may improve attention.
Most benefits are seen in children who have anemia, with improvements in thinking and memory after several months of iron.
Taking iron once a week might not work as well and could even harm some cognitive function in children who don’t have low iron levels.
There is no clear proof that iron supplements improve school grades.

Browse 9 studies3 meta-analyses

RCTEffectiveness of intermittent iron and high-dose vitamin A supplementation on cognitive development of school children in southern Ethiopia: a randomized placebo-controlled trial2024n=504

In 504 Ethiopian schoolchildren, intermittent iron plus high-dose vitamin A for 5 months improved some cognitive test scores versus placebo in this 2×2 factorial RCT.

Effect: Benefit
Duration: 5 months
Population: Children/adolescents
Participants: 504

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MetaEffects of iron supplementation on cognitive development in school-age children: Systematic review and meta-analysis2023

A meta-analysis in school-age children aged 6–12 years found iron supplementation improved some cognitive test scores, especially in iron-deficient or anemic children.

Effect: Benefit
Population: Children/adolescents
Ages: 6–12

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MetaEffect of Oral Iron Supplementation on Cognitive Function among Children and Adolescents in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis2022n=1,196

A meta-analysis of 1,196 children and adolescents in low- and middle-income countries found oral iron modestly improved intelligence and attention, with stronger effects in anemic participants.

Effect: Benefit
Population: Children/adolescents
Participants: 1,196
Ages: 5–19

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Systematic reviewIron Status, Anemia, and Iron Interventions and Their Associations with Cognitive and Academic Performance in Adolescents: A Systematic Review2022n=26

A systematic review of 26 studies found mixed evidence linking iron status and iron interventions to cognitive and academic performance in adolescents.

Population: Children/adolescents
Participants: 26

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RCTIron supplementation given to nonanemic infants: neurocognitive functioning at 16 years2021

Follow-up at age 16 of Chilean adolescents who received iron as nonanemic infants found no long-term neurocognitive differences between supplemented and unsupplemented groups.

Duration: 6–12 months
Dose: 15 mg/day
Population: Children/adolescents

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RCTEffects of iron supplementation twice a week on attention score and haematologic measures in female high school students2014

In 200 Iranian high school girls, twice-weekly 50 mg iron for 16 weeks improved attention scores and hematologic measures versus placebo.

Effect: Benefit
Duration: 16 weeks
Dose: 50 mg twice weekly
Population: Children/adolescents

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MetaThe effects of oral iron supplementation on cognition in older children and adults: a systematic review and meta-analysis2010

A meta-analysis in older children and adults found oral iron improved cognitive concentration and intelligence in anemic participants but not clearly in nonanemic iron-deficient subjects.

Effect: Benefit
Population: Adults
Ages: 6+

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RCTRandomised study of cognitive effects of iron supplementation in non-anaemic iron-deficient adolescent girls1996

In 81 non-anaemic iron-deficient adolescent girls, ferrous sulfate 650 mg twice daily for 8 weeks improved verbal learning and memory versus placebo.

Effect: Benefit
Duration: 8 weeks
Dose: 650 mg 2×/day
Population: Children/adolescents
Ages: Adolescents

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RCTThe effect of iron deficiency and mental stimulation on Indonesian children's cognitive performance and development1995n=26

In 176 Indonesian children aged 3–6 years, 8 weeks of iron improved ferritin and cognitive scores in iron-deficient anemic children but not in nonanemic iron-deficient children.

Effect: Benefit
Duration: 8 weeks
Population: Children/adolescents
Participants: 26
Ages: 3–6

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Evidence visualised

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Effect-size distribution

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Study distribution across 1 supplements for childhood cognitive function (9 studies total).
Supplement	DEX	Studies	Meta-analyses	Share
Iron	★★★★★72%	9	3	100%

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Childhood cognitive function

Overview

Effect graph

Relevant supplements

Studies

Evidence visualised

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