Iodine (potassium iodide, kelp) and thyroid function
What 2 graded rows on iodine (potassium iodide, kelp) agree on for thyroid function, 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 thyroid function
2 rows · 2,186 peopleThey agree: both rows found an improvement.
- CGrade C× 2
- Rows
- 2
- Trials
- 11
- People
- 2,186
- Pooled reviews may count some twice
What the rows share
From the rowsThe best-graded row, grade C, is a meta-analysis of 1,922 people (2026) and found an improvement.
The rows run from 264 to 1,922 people, published in 2026: 2 pooled reviews and 0 single studies.
The rows
2 improved- CGrade CTSH and thyroglobulin in iodine-deficient pregnancy · Improved
Meta-analysis, 10 studies · n 1,922 · 2026 · Iodine-deficient pregnant women (urinary iodine below 150 µg/L) in randomized trials and prospective cohorts (TSH analysis: 10 studies)
Varied; TSH fell more with 200–300 μg/day · Varied; started in different trimesters
TSH fell (SMD −0.14, 95% CI −0.23 to −0.05) and thyroglobulin fell (SMD −0.22, 95% CI −0.32 to −0.13); free T3 and free T4 did not change significantly. Thyroid volume was larger in European studies and when supplements continued after birth.
Row on the Iodine (potassium iodide, kelp) page · PubMed 42359139 (opens PubMed)
- CGrade CHypothyroidism in children in iodine-deficient areas · Improved
Systematic review · n 264 · 2026 · Children in randomized trials of iodine vs placebo (hypothyroidism analysis: 1 study)
Varied: 150 mcg daily for 28 weeks in one trial; single doses of 100–490 mg in the others · Follow-up 3 to 22 months
Iodine likely reduced hypothyroidism a lot compared with placebo (RR 0.03, 95% CI 0.00 to 0.23), moderate-certainty evidence. The effect on goitre was very uncertain.
Row on the Iodine (potassium iodide, kelp) page · PubMed 42720098 (opens PubMed)