Iodine

Best for

Protect thyroid function in pregnancy

Large effect, needs confirmation · 150–250 mcg/day for 4–26 weeks · 2 meta-analyses , n=6.3k

21 papers · 4 claims · 32 outcomes scored · 3 positive

Outcomes

What iodine actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Outcome Effect size Evidence Dose Weeks Rank

Protect thyroid function in pregnancy Large effect, needs confirmation

Keeps your thyroid stable when pregnancy doubles its workload.

9 meta-analyses n=6.3k 150–250 mcg 4–26 wk

31589645·31689890·33123091·33620551 +5 more

large

9 meta-analyses n=6.3k Meta-analyzed

150–250 mcg

4–26 wk

—

Raise low iodine levels Likely modest benefit

Fills the iodine gap your thyroid needs to build its hormone.

5 meta-analyses n=59k 35–220 g 16–74 wk #1/2

30746700·33978160·36912094·38549782 +1 more

small

5 meta-analyses n=59k Meta-analyzed I²=98%

35–220 g

16–74 wk

#1 /2

Reduce thyroid enlargement Not enough research

Shrinks goiter and brings the gland closer to normal size.

5 meta-analyses n=480 35–350 mcg 26–52 wk

21715542·25313993·30746700·31589645 +1 more

small

5 meta-analyses n=480 Meta-analyzed I²=100%

35–350 mcg

26–52 wk

—

Ease low thyroid symptoms May have slight negative effect

Reduces cold intolerance, fatigue, and brain fog from underactive thyroid.

1 meta-analysis n=4.2k — —

28282437

small

1 meta-analysis n=4.2k Meta-analyzed I²=83%

—

Outcome	Effect	Evidence	Dose	Weeks	Rank
Protect thyroid function in pregnancy Large effect, needs confirmation	large	9 meta-analyses n=6.3k Meta-analyzed	150–250 mcg	4–26 wk	—
Raise low iodine levels Likely modest benefit	small	5 meta-analyses n=59k Meta-analyzed	35–220 g	16–74 wk	#1/2
Reduce thyroid enlargement Not enough research	small	5 meta-analyses n=480 Meta-analyzed	35–350 mcg	26–52 wk	—
Ease low thyroid symptoms May have slight negative effect	small	1 meta-analysis n=4.2k Meta-analyzed	—	—	—

Buy well

Recommended Iodine products

Real products that dose Iodine where the research does, in a clean formulation, from brands we've audited. We only list ones we'd stand behind.

Chosen for adequate Iodine dosing vs. the studied range, a clean formulation (grade A–C), and independent brand-quality audits. Not sponsored.

Risk profile

Adverse events and known drug interactions

Safety events

thyrotoxicosis severe

pulmonary oedema severe

angioedema severe

subclinical hypothyroidism mild

burning sensation of mouth, throat and stomach mild

subclinical hyperthyroidism

overt hypothyroidism

hypothyroidism

Drug interactions

Amiodarone major increases toxicity

Aliskiren major increases toxicity

Ace Inhibitors And Arbs major increases toxicity

Amiloride major increases toxicity

Triamterene major increases toxicity

Spironolactone major increases toxicity

Eplerenone major increases toxicity

other major increases toxicity

Thyroid Therapy major increases toxicity

other moderate unknown

Co-studied with

Supplements that share evidence with iodine

Sources

Generated August 14, 2026

Ingredient evidence
Ingredient evidence
Selenium
All scored outcomes
Aug 14, 2026

Iodine

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