Effects of iron and n-3 fatty acid supplementation, alone and in combination, on cognition in school children: a randomized, double-blind, placebo-controlled intervention in South Africa.
What this study found
Iron supplementation improved cognition, especially learning and memory, whereas DHA/EPA did not improve cognition and showed adverse effects in some subgroups. Iron increased HVLT recall 2 by 0.90 words (95% CI: 0.18, 1.62); in anemic children, iron improved Atlantis Delayed scores by 1.51 (95% CI: 0.03, 2.99) and HVLT recall 2 by 2.02 (95% CI: 0.55, 3.49). DHA/EPA had no overall cognitive benefit and reduced Atlantis test scores in children who were anemic at baseline (22.48; 95% CI: 23.99, 20.96) and Atlantis Delayed scores in girls with iron deficiency (20.9; 95% CI: 21.45, 20.36). The…
- Study & population
- Randomized, double-blind, placebo-controlled intervention in schoolchildren aged 6-11 years from four primary schools in rural KwaZulu-Natal, South Africa.
- Intervention
- This was a 2-by-2 factorial oral supplementation trial testing iron, DHA/EPA, both together, or matching placebos for 8.5 months.
- Key limitation
- The trial had a relatively modest sample size after attrition, and several findings came from subgroup analyses, increasing the risk of chance findings.
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Open PDFOriginal abstract
BACKGROUND Little is known about the combined effects of iron and n-3 (omega-3) fatty acid (FA) supplementation on cognitive performance. The provision of either DHA/EPA or iron alone in rats with combined iron and n-3 FA deficiency has been reported to exacerbate cognitive deficits associated with deficiency. OBJECTIVE We investigated the effects of iron and DHA/EPA supplementation, alone and in combination, in children with poor iron and n-3 FA status. DESIGN In a 2-by-2 factorial trial, children with iron deficiency (ID) (n = 321; aged 6-11 y) were allocated to receive 1) iron (50 mg) plus DHA/EPA (420/80 mg), 2) iron plus placebo, 3) placebo plus a mixture of DHA and EPA (DHA/EPA), or 4) placebo plus placebo as oral supplements (4/wk) for 8.5 mo. Cognition was assessed at baseline and endpoint by using the Hopkins Verbal Learning Test (HVLT) and subscales of the Kaufman Assessment Battery for Children. RESULTS Both iron and DHA/EPA significantly increased weight-for-age z scores. Iron increased the number of words recalled at HVLT recall 2 (intervention effect: 0.90; 95% CI: 0.18, 1.62), and in anemic children, iron increased scores in the Atlantis Delayed test (1.51; 95% CI: 0.03, 2.99) and HVLT recall 2 (2.02; 95% CI: 0.55, 3.49). DHA/EPA showed no benefit in any of the cognitive tests but decreased Atlantis test scores (-2.48; 95% CI: -3.99, -0.96) in children who were anemic at baseline and decreased Atlantis delayed scores (-0.9; 95% CI: -1.45, -0.36) in girls with ID, whereas boys tended to perform better. CONCLUSIONS In children with poor iron and n-3 FA status, iron supplementation improved verbal and nonverbal learning and memory, particularly in children with anemia. In contrast, DHA/EPA supplementation had no benefits on cognition and impaired working memory in anemic children and long-term memory and retrieval in girls with ID.