Iodine supplements compared
We compare what each label says: iodine per serving, form, how big a serving is and how many you get. We have not tested any product, and we do not say how much you should take.
General information only, not medical advice. Ask a doctor or pharmacist before starting iodine, especially if you are pregnant, take medicines or have a health condition. Medical disclaimer.
Last checked November 10, 2026. How we evaluate · Corrections and updates
What the official figures say
The US Food and Drug Administration publishes one reference figure for each nutrient, the Daily Value (FDA, content current as of March 5, 2024):
- FDA Daily Value for iodine: 150 mcg a day, the figure the %DV on labels is based on.
The FDA describes Daily Values as the recommended amounts of nutrients to consume or not to exceed each day, and the %DV on a Supplement Facts label is based on them. It is one figure for the label, so it does not show differences by age, sex or pregnancy, or an upper limit. The FDA Daily Value table does not give an upper limit, and we state none. The NIH Office of Dietary Supplements publishes a fact sheet on iodine; we have not read it for this page, and we link it as a place to look for amounts by age, sex and pregnancy and for upper limits. Ask a doctor or pharmacist about medicines and about any serving above the Daily Value. Source: FDA, Daily Value on the Nutrition and Supplement Facts Labels, content current as of March 5, 2024.
How to read an iodine label
- Units. Check the unit on each label (mg or mcg). Compare figures in the same unit.
- Compare the amount, not the product type. Two products in the table are named as kelp tablets and one product name includes tyrosine. Compare the iodine figure in the Per serving column.
- Serving size. Check how many capsules, tablets, softgels or scoops make one serving before you compare doses or count servings.
- Form. The label may name a form, such as potassium iodide, or the kelp it comes from.
- Percent Daily Value. The %DV on a label compares one serving with the Daily Value above. The records here give it for adults and children 4 or more years of age.
- Other ingredients. Read the "Other ingredients" list for allergens and added ingredients.
- Independent testing. A testing or certification mark on a label is a statement on the label record, and we have not checked any mark with the certifier. The table quotes the marks a record states (Kosher, Halal and GMP statements are not listed). Check each one on the certifier's own site.
- Your total. The amounts on different labels add up across every supplement and multivitamin.
Comparison
Only products whose label data we have read appear here: on the maker's own page, or in the National Institutes of Health's Dietary Supplement Label Database (DSLD), which records labels as submitted. A label can change after it was recorded. Selection is not a sales ranking. We will add Amazon best-seller positions only with a dated source.
| Product | Per serving | % DV on label | Servings | Form | Marks on the label | Label record |
|---|---|---|---|---|---|---|
| Pure Encapsulations Iodine (Potassium Iodide), 120 Capsule(s) | 225 mcg per serving (1 Capsule(s)) | 150% | 120 | Potassium Iodide | Gluten-Free Certification Organization (GFCO) | Source |
| Thorne Iodine & Tyrosine, 60 Capsule(s) | 225 mcg per serving (1 Capsule(s); the product also contains tyrosine, per its name) | 150% | 60 | Potassium Iodide | No testing mark stated in the record | Source |
| NOW Kelp, 200 Tablet(s) | 150 mcg per serving (1 Tablet(s)) | 100% | 200 | Kelp (product name; the DSLD record lists no ingredient form) | No testing mark stated in the record | Source |
| Solgar North Atlantic Kelp, 250 Tablet(s) | 200 mcg per serving (1 Tablet(s)) | 133% | to be verified | North Atlantic kelp (product name; the DSLD record lists no ingredient form) | Certified Gluten-Free (certifier not named in the record) | Source |
All 4 products print a %DV, from 100% to 150% of the Daily Value. The NOW and Solgar products are kelp tablets, and the Thorne product also contains tyrosine. The Solgar record dates from 2020. A clinician can say whether a serving above the Daily Value is appropriate for you.
Marks are quoted from each product's label record and have not been checked with the certifier. Kosher, Halal and GMP statements are not listed.
Products are added as their labels are read. Where a maker's site blocks automated reading, we wait until the label is available on the maker's page or in the DSLD instead of copying it from a retailer.
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Questions
Does a higher dose mean a better product?
A higher dose is a larger number on the label, not a measure of quality. We do not rank products by dose.
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