Third-Party Tested Iron Supplements (2026): The 8 of 33 on a Public List
8 of the 33 iron supplements we score are on a public testing list: Nature Made, Piping Rock, OLLY, Klean Athlete, Thorne and Momentous. 5 of those are also screened for drugs banned in sport. Our pick for low iron, Nature Made Iron 65 mg, is on Informed Choice + USP Verified.
By Erin Rose Updated October 6, 2026 How we score
What each testing list checks
Two kinds. A contents program checks that the product holds what the label says. A banned-substance program screens for drugs banned in sport, which matters only if you are drug-tested.
| List | What it checks | How it samples |
|---|---|---|
| NSF/ANSI 173contents | That the product holds the ingredients on the label and nothing else, and has no harmful levels of contaminants. | Annual audits, and NSF retests each product from time to time. Not a banned-substance program. |
| USP Verifiedcontents | That the product holds the ingredients on the label in the stated amounts, has no harmful levels of listed contaminants, breaks down in a set time, and is made under FDA good manufacturing practice. | Audits, lab tests before listing, and tests of listed products bought off the shelf. |
| NSF Certified for Sportbanned substances | The label matches the contents, plus screening for substances banned in sport. | Factory audits; listings can be searched by lot. |
| Informed Choicebanned substances | Banned substances. | Samples bought from stores at least monthly and blind tested. |
| Informed Sportbanned substances | Banned substances. | Every batch, before it is released to market. |
Which iron we score is on which list
| Product | Lists |
|---|---|
| Nature Made Iron 65 mg | Informed Choice, USP Verified |
| Piping Rock Iron 65 mg | NSF/ANSI 173 |
| Piping Rock Slow Release Iron 45 mg | NSF/ANSI 173 |
| OLLY Delightful Iron 18 mg chewable | NSF/ANSI 173 |
| Klean Athlete Klean Iron 27 mg | NSF Certified for Sport, NSF/ANSI 173 |
| Thorne Iron Bisglycinate 25 mg | NSF Certified for Sport, NSF/ANSI 173 |
| Thorne Advanced Iron Complex 36 mg | NSF Certified for Sport, NSF/ANSI 173 |
| Momentous Iron+ 25 mg | NSF Certified for Sport, NSF/ANSI 173 |
NSF lists Piping Rock’s iron under its maker name, Piping Rock Health Products DBA Nature’s Truth. The other 25 we score are on none of the five lists.
What the brand says, and what we could confirm
| What the brand says | How many of the 33 we score |
|---|---|
| On a public list | 8 products, every one in the table above |
| Says “third-party tested” | 4products |
| Says it is tested, names no outside lab | 5products |
| Other seals (gluten-free, non-GMO, purity) | 6products |
| No testing claim | 10products |
A claim with no listing is the brand’s word: no outside group has checked it.
Which tested iron to buy
For low iron found on a blood test, our pick above. If it upsets your stomach, Thorne Iron Bisglycinate 25 mg, a gentler bisglycinate on NSF Certified for Sport + NSF/ANSI 173. The other listed products:
- Buy Piping Rock Iron 65 mg (250 tablets) on Amazon
- Buy Piping Rock Slow Release Iron 45 mg (200 tablets) on Amazon
- Buy OLLY Delightful Iron 18 mg chewable (60 tablets) on Amazon
- Buy Klean Athlete Klean Iron 27 mg (90 tablets) on Amazon
- Buy Thorne Iron Bisglycinate 25 mg (60 capsules) on Amazon
- Buy Thorne Advanced Iron Complex 36 mg (60 capsules) on Amazon
- Buy Momentous Iron+ 25 mg (60 capsules) on Amazon
How to check your bottle
- Find the mark. Look for an NSF or USP mark. “Third-party tested” with no mark is a claim.
- Open the program’s own list. NSF/ANSI 173, USP Verified, NSF Certified for Sport, Informed Choice, Informed Sport. Or search all five on our testing-list index.
- Search the product, not just the brand. A brand with one listed product can sell others that are not.
- Try the maker’s name. NSF/ANSI 173 files products under the company that makes them.
Questions
Which iron supplements are third-party tested?
Of the 33 we score, 8 are on a public testing list: Nature Made Iron 65 mg, Piping Rock Iron 65 mg, Piping Rock Slow Release Iron 45 mg, OLLY Delightful Iron 18 mg chewable, Klean Athlete Klean Iron 27 mg, Thorne Iron Bisglycinate 25 mg, Thorne Advanced Iron Complex 36 mg and Momentous Iron+ 25 mg.
Is Thorne iron NSF certified?
Yes. Thorne Iron Bisglycinate is on NSF/ANSI 173 (1 capsule a serving) and NSF Certified for Sport (listing 1205059). Thorne Advanced Iron Complex is on both lists too.
Is Nature Made iron USP Verified?
Yes. USP’s list includes “Nature Made Iron 65 Mg Tablets” (our copy of September 22, 2026), and Informed Choice lists “Nature Made Iron” (read October 5, 2026). The Nature Made iron gummy is not on either list.
Is Solgar Gentle Iron third-party tested?
Not on any public list we search: NSF/ANSI 173, NSF Certified for Sport, USP Verified, Informed Choice or Informed Sport. Its label carries gluten-free, kosher, halal and non-GMO seals, which are not tests of what is in the capsule.
Is MegaFood Blood Builder NSF certified?
Not that we could find. MegaFood says it tests for pesticides and herbicides, but Blood Builder is not on NSF/ANSI 173 or any other public list we search.
Does “third-party tested” on the label mean anything?
On its own, no. The phrase has no set meaning. A listing on a public program is something you can check yourself; a label claim is the brand’s word.
Sources
- NSF/ANSI 173 (info.nsf.org), NSF Certified for Sport (nsfsport.com) and Informed Choice (choice.wetestyoutrust.com), read October 5, 2026. USP Verified and Informed Sport from our copies of September 22, 2026 (USP’s site blocks automated reads).
- Brand claims: each brand’s label (NIH Dietary Supplement Label Database) or store page, read October 6, 2026. Prices: each brand’s list price, checked October 6, 2026.