Effects of multiple micronutrient supplementation on cognitive function in children: a systematic review and meta-analysis of randomized controlled trials
Asgari Avini N, Shahinfar H, Yazdian Z, Ranjbar M, Shab-Bidar S · 2026
grade Cmeta-analysisindependentunreplicated
Sample
35 RCTs, 19,343 participants; searched to 11 May 2025
Population
Children and adolescents aged 18 and under, international, mixed baseline micronutrient status.
Design
Updated and much larger successor to Eilander 2010, restricted to RCTs comparing three or more micronutrients against placebo or control. Cochrane risk-of-bias tool applied by two independent reviewers - and ONLY FOUR OF THIRTY-FIVE TRIALS were rated low risk of bias. Outcomes split into nine cognitive domains, random-effects pooling, GRADE applied per domain. Graded C here because the pooled trials are overwhelmingly high or unclear risk of bias, which is what the GRADE ratings reflect.
Key findings
With 19,343 children and 35 trials, only two of nine cognitive domains move at all. Memory SMD 0.22 (95% CI 0.08 to 0.35, P = 0.002) but with I2 = 73.8% and GRADE rated VERY LOW. Language SMD 0.09 (95% CI 0.03 to 0.16, P = 0.006), I2 = 39%, GRADE high - a 0.09 SD effect on language is the single high-certainty result in the modern micronutrient literature. No significant effects in any other domain, including any intelligence measure. The authors conclude the data are insufficient to support regular MMN intake for cognitive improvement in children.
Genetic confound
None internally - randomized placebo-controlled trials. The residual risk is publication and reporting bias given that only 4 of 35 trials were low risk of bias.
Effects
| Outcome | Metric | Value | Measure | Timing | Vs | Horizon | Class |
|---|---|---|---|---|---|---|---|
| Memory (near transfer) | pooled SMD | 0.22 (95% CI 0.08 to 0.35), P = 0.002, I2 = 73.8%, GRADE very low | mixed | end of supplementation | business-as-usual | end-of-treatment | near-transfer |
| Language (domain skills) | pooled SMD | 0.09 (95% CI 0.03 to 0.16), P = 0.006, I2 = 39%, GRADE high | mixed | end of supplementation | business-as-usual | end-of-treatment | domain-skill |
| All other cognitive domains including intelligence | pooled SMD | no significant effect | mixed | end of supplementation | business-as-usual | end-of-treatment | g |
| Risk of bias of the evidence base | Cochrane RoB rating | 4 of 35 trials low risk of bias | standardized | n/a | none | not-applicable | domain-skill |
Cited by
- Breakfast, school meals, and micronutrients — what feeding children actually buysmixedconf: mediumgc: low