Why the thyroid needs iodine
Your body needs iodine to make thyroid hormones, which control metabolism and support bone and brain development in pregnancy and infancy.1 Iodine deficiency is the most common cause of goiter, an enlarged thyroid.8
Why the thyroid needs iodine
A simplified illustration based on NIH ODS and MedlinePlus.
Where to get it
Iodized salt is the main food source,3 alongside seafood, dairy and eggs.2 Processed foods and specialty salts are usually not iodized.4
Where iodine comes from
Who may fall short
Most people in the U.S. get enough.12 Pregnant women need about 50% more,5 and vegans or people who eat little dairy, seafood or eggs may fall short.6
Who may fall short, and who should be careful
| Who | Why |
|---|---|
| Pregnant women | Need about 50% more iodine.5 |
| Vegans, or little dairy, seafood or eggs | These are the best food sources.6 |
| People on antithyroid medicine | High-dose iodine can push thyroid hormone too low.10 |
| Anyone taking kelp or a multivitamin | Both can contain iodine; add it up.11 |
Severe deficiency in pregnancy can permanently harm the baby's development.7
Too much iodine
High iodine intake can cause goiter, thyroid inflammation and thyroid cancer,9 and high-dose iodine with antithyroid medicines can push thyroid hormone too low.10 Kelp and many multivitamins contain iodine.11 Thyroid problems matter: an untreated overactive thyroid can cause an irregular heartbeat, clots and stroke.16
How common thyroid problems are in the U.S.
A historical perspective: Dr. Majid Ali
“I have seen three cases of iodine toxicity created by blind, heavy, and prolonged iodine therapy.”
— Dr. Majid Ali, 16 October 2015
Dr. Ali warned against taking iodine for long without testing. That is consistent with current sources: too much iodine can harm the thyroid.918
He also credited iodine with healing many unrelated disorders. The sources used here do not support that.
What to do this week
Check your salt label
If pregnant, ask about iodine
You need about 50% more.5
Add up hidden iodine
Kelp and multivitamins both contain it.11
Ask before iodine with thyroid medicine
It can push thyroid hormone too low.10
When to get help now
Each warning sign cites the official guidance behind it. The wording still needs pharmacist sign-off.
- A racing or irregular heartbeat, chest pain or fainting — call 911.2021
- A neck swelling that makes it hard to breathe or swallow — contact your provider. If breathing suddenly becomes hard, call 911.2223
- Severe tiredness, confusion or feeling very cold with a known underactive thyroid — seek care promptly.24
- New palpitations, weight loss or shakiness after starting iodine or kelp — stop and see a provider.252627
- Pregnant and taking a thyroid medicine — contact your doctor right away about the dose.28
Every numbered marker links to the exact passage it rests on. Check the sources.