Which iron supplements are third-party tested?

By Erin Rose · Published October 5, 2026 · Checked October 3, 2026 · Methodology

Not medical advice. This page checks products against public certification registries and the brands’ own published lab reports; it does not test products itself.

One category of our third-party tested supplement database: every product we track, checked against NSF, USP Verified and Informed Sport, searchable by brand.

Every iron product we track, on the verification ladder

Original research12 iron supplements sold on Amazon, checked one by one on October 3, 2026: the full NSF/ANSI 173 list, the full NSF Certified for Sport list, all 14 pages of the USP Verified list, and the Informed Sport and Informed Choice searches. Then each brand’s own site and Amazon page for a lab report tied to a lot. NSF lists read again October 5, 2026. A match means the exact product, never the brand alone.

Method: the roster is 12 widely sold iron supplements on Amazon, across the main forms (bisglycinate, ferrous sulfate and carbonyl iron); the table shows the ones with an Amazon offer on the date shown. Registry matches are exact-product matches (name, form and, where the registry lists it, flavour) against each registry, never a brand-level match; the certificate check read each brand’s own site for a published, lot-specific certificate of analysis. A product whose brand site blocked the check is recorded as unverified, not as failing. Cost is computed from the Amazon price of the exact container on October 5, 2026 and the dose on its Supplement Facts panel.

The rung is decided by what a buyer can look up, not by what the label says. Rung 1 means the exact product appears in a certifier’s public registry; the listing text is quoted so you can find it. Rung 2 means the brand publishes a certificate of analysis for a specific lot. Rung 3 is a lab report with no lot to match. Rung 4 is a claim, silence, or a brand site that blocked our check. Within a rung, products are ordered by cost per serving.

Registry results are from our search of each registry on the date shown; a listing can be added or withdrawn after that date, so confirm the lot on your bottle against the live registry before relying on it. Prices are Amazon prices on October 5, 2026, divided by servings.

How much iron one serving holds

Cost is per labelled serving, and the iron in a serving differs a lot between products, from 15 mg to 65 mg. Compare the iron row on the label, not the bottle size.

Iron per serving and form from each product’s label or Amazon listing, read October 3, 2026. Cost is the Amazon price on October 5, 2026 divided by servings per bottle.

What each mark actually checks

NSF/ANSI 173 (the “NSF Contents Certified” mark, listed at info.nsf.org) verifies that the label is accurate, that contaminants such as heavy metals and microbes are within limits, and audits the manufacturing facility. NSF Certified for Sport is the same program plus a screen of every lot for more than 280 substances banned by major athletic organizations; it is the mark most professional leagues and anti-doping bodies name. USP Verified checks identity, potency and contaminants, that a tablet or capsule dissolves, and audits manufacturing to USP’s standard; its list is short (14 pages when we read it on October 3, 2026) and dominated by a few large brands. Informed Sport tests every batch for banned substances at an ISO 17025 laboratory and publishes the batch; Informed Choice tests retail samples on a schedule instead of every batch. None of these programs measures whether iron works; they measure whether the container holds what the label says.

Iron is sold in several forms (bisglycinate, ferrous sulfate, carbonyl iron) and at 15 to 65 mg of iron per serving across the 12 products here. A testing program checks that the iron on the label is the iron in the tablet, and that metals and microbes are within limits. Three of the 12 are on a public registry: Thorne Iron Bisglycinate and Klean Athlete Klean Iron are on NSF/ANSI 173 and on NSF Certified for Sport, and Nature Made Iron 65 mg is on the USP Verified list. Three more say they are tested but name no outside lab for the product and post no report we could find: NOW cites a factory audit and its own labs, and MegaFood and Pure Encapsulations say outside labs test their products. MegaFood is on NSF’s list, but only for a creatine powder, not Blood Builder. The other six, including Solgar Gentle Iron, make no testing claim we found. Vitron-C’s Amazon page links a file named “Certificate of Analysis”; we opened it, and it is a photo of the carton, with no lab name and no test results.

None of these programs tells you whether you need iron or how much. They check the bottle, not the person. A review of supplement contamination in the US advises athletes who are drug-tested to use third-party certified products (Mathews 2018, PMID 28850291). That is the extra step NSF Certified for Sport adds, and two of the three iron products on a registry carry it.

Which iron to buy

Product links go to Amazon and we may earn a commission if you buy. It never changes which product we pick or what we say about it. How we choose.

How to check your own bottle

1. Find the lot number, usually stamped on the bottom or near the seal.
2. NSF: search the product at info.nsf.org (NSF/ANSI 173) or nsfsport.com (Certified for Sport). The listing names the exact product and form.
3. Informed Sport / Informed Choice: search the brand at sport.wetestyoutrust.com; each product page lists tested batches.
4. USP Verified: the list is at quality-supplements.org.
5. Brand lab reports: none of the 12 brands posts a lot report for these iron products that we could find. If yours does, match the lot number on your bottle. A report without a lot number is rung 3, not rung 2.

The iron warning on every bottle

Federal rules require iron tablets and capsules sold as supplements to carry this warning, word for word:

WARNING: Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6. Keep this product out of reach of children. In case of accidental overdose, call a doctor or poison control center immediately.

Source: 21 CFR 101.17(e)(1), eCFR, current as of October 1, 2026, read October 5, 2026. A testing mark checks what is in the bottle, not how much iron you need. Ask your doctor or pharmacist before you start iron.

Frequently asked questions

Related guides

• Best iron bisglycinate, ranked by dose and cost
• Solgar vs Thorne iron bisglycinate
• Ferrous sulfate vs bisglycinate
• Third-party tested supplement database
• How few supplements are certified at all: the registry audit

Sources