vitaminEVIDENCEAUSOTC

Iodine

Essential trace mineral; the active ingredient in thyroid hormones T3 and T4. Deficiency causes cognitive impairment and goiter; most common in regions without iodised salt.

Dose range0.15–1mg

Half-life—h

Onset—min

Safety4/5high evidence base

Mechanism of action

Incorporated into thyroid hormones T3 (triiodothyronine, with 3 iodine atoms) and T4 (thyroxine, with 4 iodine atoms). The hormones regulate metabolic rate, neural development, body temperature, and energy expenditure. Adult deficiency produces hypothyroidism, fatigue, cognitive slowing, weight gain. Childhood deficiency produces cretinism with permanent cognitive impairment.

History

Iodine deficiency disorders were historically the leading preventable cause of cognitive impairment globally. Iodised salt programs starting in the 1920s eliminated cretinism in iodised countries. Continued vigilance is required — recent data shows resurgent mild deficiency in iodine-restricted diets (vegan, low-salt, raw-food). The Japanese diet provides ~1000-3000 mcg/day from seaweed; Western diets without iodised salt or seafood typically provide much less. Unscheduled globally.

Benefits

Thyroid function
EVIDENCEA
Universally accepted.
Cognitive function in deficient populations
EVIDENCEA
Multiple meta-analyses.

Side effects

Thyroid dysfunction (excess)uncommonmoderate
Hashimoto's exacerbationuncommonmoderate

Cited research

Iodine deficiency disorders: scope and approach review2008
PMID 18646559 ↗
Iodine status and cognitive function in children: meta-analysis2013
PMID 23266932 ↗
Iodine supplementation in adults: review (Zimmermann)2013
PMID 23415945 ↗

Where to buy

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Vendor	Product	Size	Price	Per unit
ThorneFeatured 4.6	Iodine — Thorne	—	See vendor	—	Shop Ad
Life Extension 4.3	Iodine — Life Extension	—	See vendor	—	Shop Ad
NOW Foods 4.1	Iodine — NOW Foods	—	See vendor	—	Shop Ad
Amazon Marketplace 3.5	Iodine — Amazon	—	See vendor	—	Shop Ad

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