Iodine
The thyroid builds iodine into thyroid hormones, and these hormones regulate metabolism throughout the body.
Full ranking Dose tool Products (2,957)
Key facts
Sources: https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/ · FDA DV 150 mcg (https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels); pre-2016 DV [] (https://www.federalregister.gov/documents/2016/05/27/2016-11867/food-labeling-revision-of-the-nutrition-and-supplement-facts-labels); adult UL 1100 mcg
How it works: Why is iodine linked to the thyroid?
- After iodine is absorbed, the thyroid takes it up from the blood; TSH from the pituitary regulates this.
- The thyroid uses iodine to make the thyroid hormones T4 and T3.
- Thyroid hormones regulate protein synthesis, enzyme activity and metabolic rate, and matter for bone and brain development in fetuses and infants.
Schematic only; positions and scale are not anatomical.
Sources: NIH ODS: Iodine Fact Sheet for Health Professionals
Daily dose across products (mcg/day)
Label data from official national databases and brand websites, as declared; not lab-verified.
Common forms
| Form | Products | Median | P5–P95 | Elemental fraction |
|---|---|---|---|---|
| Iodine potassium iodide | 1929 | 150 mcg | 21 – 1,911 | 76.4% [source] |
| Iodine kelp | 403 | 150 mcg | 13 – 380 | — |
Common questions
What is the Daily Value for Iodine?
The US FDA Daily Value for adults and children aged 4 and over is 150 mcg. It is a labelling reference, not a personal recommendation. [source]
Is there an upper limit for Iodine?
The adult Tolerable Upper Intake Level (UL) is 1,100 mcg per day. Going above it long term raises the risk of adverse effects. See the linked source. [source]
How much Iodine do products usually contain per day?
As of 2026-11-01, 2,957 products list a comparable daily dose (3,154 dose records; one product can have several). The median is 150 mcg per day, and 90% of records fall between 15 and 5,000 mcg. Figures come from labels and are not lab-tested. [source]
Why is iodine linked to the thyroid?
The thyroid builds iodine into thyroid hormones, and these hormones regulate metabolism throughout the body. Adult UL: 1,100 mcg per day. Both too much and too little iodine can cause thyroid problems. [source]
What are the side effects of Iodine?
Too much iodine can cause some of the same symptoms as deficiency, including goiter, and can cause thyroid inflammation and thyroid cancer. A very large dose (several grams) can cause burning of the mouth, throat and stomach, fever, nausea, vomiting, diarrhea, weak pulse and coma. (Source: NIH ODS) [source]
What happens if you take too much Iodine?
The adult UL is 1,100 mcg a day from all sources. Kelp supplements can contain a lot of iodine, so check the label. (Source: NIH ODS) [source]
Is Iodine safe during pregnancy and breastfeeding?
The recommended amount is 220 mcg a day in pregnancy and 290 mcg while breastfeeding; pregnant women need about 50% more than others. The American Thyroid Association recommends a daily supplement with 150 mcg iodine (as potassium iodide) for women who are pregnant, planning pregnancy or breastfeeding; only about half of US prenatal vitamins contain iodine. (Source: NIH ODS) [source]
Does Iodine interact with medications or other supplements?
High-dose iodine with antithyroid drugs such as methimazole could make your body produce too little thyroid hormone. Potassium iodide with ACE inhibitors (such as benazepril, lisinopril) or potassium-sparing diuretics (such as spironolactone, amiloride) could raise blood potassium to unsafe levels. (Source: NIH ODS) [source]
Top ranked
| Rank | Brand | Product | Per day | Score |
|---|---|---|---|---|
| 1 | Bulletproof | Iodine 150 mcg | 300 mcg | 100.0 |
| 1 | Solaray | Iodine 500 mcg | 500 mcg | 100.0 |
| 1 | NutraChamps | Iodine Liquid Drops Unflavored | 250 mcg | 100.0 |
| 4 | Whole Foods Market | Iodine from Kelp | 225 mcg | 97.8 |
| 5 | Pure Encapsulations | Iodine (Potassium Iodide) | 450 mcg | 94.4 |