Best Iodine Supplements 2026: Cost per Effective Dose
Our pick for Iodine: Nutricost Kelp Tablets, 325mcg Iodine — 325mcg per 1 tablet, $0.05/day. Our pick.
Registry check · Iodine
Does anyone independently verify Iodine supplements?
We did not find any of these products in a public registry, and none of the listings names a certification mark. Where a listing names a mark, we say so in the table; where we could not find it in a registry, we say that instead.
The 4 products on this page checked against all 5,317 US NSF, USP and Informed Sport listings, 2026-08-25. Full method and limitations.
What Iodine labels show
Priced per day, these iodine products run $0.03 to $0.11 — a 3.7× gap between the cheapest and priciest iodine here, across 3 brands.
Which row that favors is not obvious: NOW Foods NOW Supplements Kelp, 150mcg Natural Iodine is cheapest per serving at $0.03, but its serving sits below the median here, so part of that price gap is simply a smaller capsule.
All Iodine Supplements Compared
| Product | Brand | Dose / Serving | Cost / Day | Certification (as labeled) | Pick | Buy |
|---|---|---|---|---|---|---|
| NOW Supplements Kelp, 150mcg Natural Iodine | NOW Foods | 150mcg / 1 tablet | $0.03 | None | Buy | |
| NOW Supplements Kelp, 325mcg Natural Iodine | NOW Foods | 325mcg / 1 veg capsule | $0.05 | None | Buy | |
| Nutricost Kelp Tablets, 325mcg Iodine | Nutricost | 325mcg / 1 tablet | $0.05 | None | Our pick | Buy |
| Life Extension Sea-Iodine, 1000mcg | Life Extension | 1,000mcg / 1 veg capsule | $0.11 | None | Buy |
Our picks
Our pick: Nutricost Kelp Tablets, 325mcg Iodine
325mcg per 1 tablet. $0.05/day. 240 servings per container at $11.95.
How these 4 Iodine products were ranked
Not one of these 4 iodine products could be confirmed in the NSF, USP or Informed Sport registries, so verification separates none of them and the ranking falls to cost per day at the labeled serving. Commission does not enter it: the rate is the same whichever iodine you buy. Full methodology.