The thyroid uses iodine to make hormones that affect metabolism. The aim is enough, not the highest possible intake. This text gives general information and does not replace an examination or test results.
How much and from where
Adults need about 140 to 150 micrograms a day, a little more during pregnancy and breastfeeding. Most people reach this with a varied diet. Good sources are fish and seafood, dairy, eggs and iodised salt. Sea salt and other specialty salts are often not iodised.
Why too much is a problem
Long term high doses of iodine can upset thyroid function. Seaweed and kelp supplements are especially strong sources, because the amount of iodine varies greatly. The upper intake limit depends on local reference values and differs between countries. It is not a target or a recommended dose for taking supplements on your own.
What to do
- Look at your diet first: do you eat fish, dairy and iodised salt?
- If you have a thyroid diagnosis or take levothyroxine, discuss every supplement with your doctor or pharmacist.
- Find the iodine amount on the label and do not exceed it. Avoid kelp and seaweed supplements without advice.
- Pregnant and breastfeeding women should decide about iodine with their doctor.
Tiredness, restlessness, a racing heart, weight change or a swelling in the neck are reasons for an examination and blood tests, not for adding iodine on your own. An underactive thyroid is treated with medicine prescribed by a doctor.
When you buy salt, check that the pack says it is iodised, because sea salt and other specialty salts often have no added iodine. Bring your results, a list of medicines and your questions to the check up with your doctor.
Sources: NHS NIH Office of Dietary Supplements NHS EFSA.
Common questions
Do I need an iodine supplement if I do not eat fish?
Not necessarily. Iodised salt and dairy are also sources. If you avoid all of these, agree with a doctor or dietitian whether a supplement is needed.
Can an iodine supplement treat a thyroid problem?
No. A supplement does not replace diagnosis or treatment, and too much iodine can make things worse. Agree any change with your doctor.
Before first use
Choose products for your dietary routine and care needs. Follow a healthcare professional’s advice for diagnosis and treatment of symptoms. Check suitability first during pregnancy and for use by children.
