Iodine (potassium iodide, kelp) and brain & focus
What 3 graded rows on iodine (potassium iodide, kelp) agree on for brain & focus, and where they differ. Counted side by side, never averaged.
Consensus finder Rows from the Iodine (potassium iodide, kelp) page, reviewed Oct 21, 2026 How it decides
What the rows agree on
Each block and row is one graded row from the Iodine (potassium iodide, kelp) page, with its PubMed record.
Your question
Iodine (potassium iodide, kelp) and brain & focus
3 rows · 789 peopleMostly an improvement: 2 of 3 rows, and most of the people. 1 found no difference.
- BGrade B× 2
- ∅No effect× 1
- Rows
- 3
- Trials
- 3
- At least: a review without a trial count
- People
- 789
- Pooled reviews may count some twice
Where they differ
From the rowsThe best-graded row, grade B, is a randomized trial of 310 people (2006) and found an improvement. 1 row is graded No effect, our grade for adequately powered trials that found no effect.
Only the 2 rows that found an improvement include pooled reviews of several trials (1 of 2); the row that found no difference is a single study.
Only the row that found no difference names women in its population.
The rows
2 improved · 1 no difference- BGrade BInformation processing and problem solving in moderately deficient schoolchildren · Improved
RCT · n 310 · 2006 · Iodine-deficient children aged 10-12 in rural Albania (median urinary iodine 43 microg/L; 87% with goiter)
400 mg iodine as oral iodized oil · 24 weeks
Iodine improved iodine and thyroid status and performance on 4 of 7 cognitive and motor tests (information processing, fine motor skills and visual problem solving) vs placebo.
Row on the Iodine (potassium iodide, kelp) page · PubMed 16400058 (opens PubMed)
- BGrade BCognitive scores in iodine-deficient children · Improved
Systematic review · n 166 · 2026 · Children and adolescents in randomized trials of iodine vs placebo (cognition analysis: 1 study)
Varied across trials · Varied across trials
Iodine slightly increased cognitive function vs placebo (SMD 0.19; 95% CI 0.04 to 0.34), high-certainty evidence. Weight showed little to no difference (low certainty).
Row on the Iodine (potassium iodide, kelp) page · PubMed 42720098 (opens PubMed)
- ∅No effectChild IQ and executive function after supplementing mildly deficient pregnant women · No difference
RCT · n 313 · 2017 · Mildly iodine-deficient pregnant women in Bangalore, India and Bangkok, Thailand; children assessed at 5-6 years
200 μg iodine/day · From early pregnancy (mean 10.7 weeks) until delivery
No difference in verbal IQ (difference -0.7; 95% CI -2.9 to 1.5), performance IQ (-1.6) or executive function. Adverse events did not differ between groups.
Row on the Iodine (potassium iodide, kelp) page · PubMed 29030199 (opens PubMed)