Mineral
Iodine
An essential mineral required for thyroid function and cognitive development.
KÖGN Health grades Iodine as A (Strong evidence) and rates it 4.2 out of 5.
Last reviewed · June 2026
Primary effects
- Improved cognitive function
- Energy regulation
- Brain development
How it works
Supports thyroid hormone production, which regulates brain development and metabolism.
Overview
Iodine is critical for proper thyroid function, which in turn regulates metabolism and cognitive performance. Deficiency can lead to significant cognitive impairment, making it one of the most important nutrients for brain health. However, excessive intake can be harmful, so balance is essential.
The evidence
Iodine is required to make thyroid hormones, which are essential for brain development. Its strongest cognitive evidence is developmental: deficiency in pregnancy and early childhood lowers IQ — a meta-analysis estimated around 7–8 IQ points — and correcting it protects development. In iodine-replete adults, extra iodine does not enhance cognition, and too much can disturb the thyroid.
How to dose it
The adult requirement is about 150 µg/day (higher in pregnancy and breastfeeding). Most people meet this through iodised salt, dairy and seafood, so supplements are usually modest.
When to take it
Chronic — and most critical during pregnancy and early life.
Safety & side effects
Iodine has a narrow window: both too little and too much impair thyroid function. An upper limit of around 1,100 µg/day is commonly cited for adults.
Who should avoid it
Avoid high-dose iodine (including kelp supplements) if you have thyroid disease without medical advice, as it can trigger over- or under-activity. Take care alongside thyroid medication, lithium, or amiodarone.
References
Related ingredients
Graded entries that target the same cognitive goals.
Categories
Draft — the dose, safety and evidence notes on this entry were prepared from the published literature and are pending editorial and clinical review.
Educational information, not medical advice. The evidence grade is KÖGN’s editorial assessment of published research, not a health claim. Speak to a qualified clinician before changing what you take.