Third-party tested omega-3: the real list
Purity results re-read from every IFOS certificate on 4 October 2026; the descriptions of the testing programmes were last reviewed July 2026.
To compare omega-3 supplements on purity, read the certificate: of the 12 fish oils on this site, 10 publish an IFOS certificate with measured contaminants. All 10 are marked compliant for mercury, lead, cadmium and arsenic. Measured PCBs run from 0.245 ppb (OmegaVia EPA 500) to 24.8 ppb (Wiley's Finest Peak EPA, lot expired 02/2021) against the IFOS limit of 45 ppb, and TOTOX from 3.49 to 17.74 against 19.5. Read from each certificate on 2026-10-04.
"Third-party tested" gets printed on a lot of boxes. It should mean an independent lab — not the brand — verified what's in the bottle. But the phrase is unregulated, so the useful question isn't "does it say third-party tested?" It's "can I see the certificate?" This page is about the programs whose results are actually public, and how to read them.
The programs that publish results
- IFOS (Nutrasource) — the most detailed for fish oil. Publishes per-batch certificates with measured EPA/DHA, oxidation (TOTOX), PCBs and heavy metals. This is the data our ranking is built on.
- NSF Certified for Sport — verifies contents and screens for banned substances; widely trusted, but the public listing is pass/fail, not a numbers sheet.
- USP Verified — confirms identity, potency and purity to USP standards; again a verified/not-verified listing rather than published assay values.
ConsumerLab and Labdoor also test supplements, but their detailed results sit behind a paywall or are proprietary — useful to know they exist, but you can't independently pull the numbers.
What third-party testing does — and doesn't — tell you
A certificate confirms the tested batch: that the EPA/DHA is really there, the oil is fresh, and contaminants are low. It does not promise a health outcome, and it doesn't cover batches it didn't test. Ratings are lot-specific. Treat a certificate as evidence about one production run, not a permanent grade.
Purity at a glance: what each certificate measured
From each product's public IFOS certificate, read 2026-10-04. Full heavy-metal values: fish oil heavy metals, by product.
| Product | PCBs (ppb) | Dioxins + furans (ppt) | Heavy metals | TOTOX | IFOS certificate |
|---|---|---|---|---|---|
| Carlson Elite Omega-3 Gems | 0.369 | 0.0496 | All 4 compliant | 17.74 | lot SB017377 |
| Carlson Super Omega-3 Gems | 0.364 | 0.193 | All 4 compliant | 17.21 | lot SB017012 |
| Carlson The Very Finest Fish Oil | 0.351 | 0.166 | All 4 compliant | 9.28 | lot 0011224 |
| Life Extension Super Omega-3 | 0.525 | 0.149 | All 4 compliant | 11.41 | lot C2600194 |
| OmegaVia DHA 600 | 0.247 | 0.204 | All 4 compliant | 6.73 | lot OV250191 |
| OmegaVia EPA 500 | 0.245 | 0.196 | All 4 compliant | 12.85 | lot OV250446 |
| OmegaVia Ultra Concentrated Omega-3 | 1.08 | 0.106 | All 4 compliant | 14.84 | lot OV250490 |
| Sports Research Triple Strength Omega-3 | 0.596 | 0.182 | All 4 compliant | 9.58 | lot UC260228 |
| Viva Naturals Triple Strength Omega-3 | <5 | <1.0 | All 4 compliant | 6.44 | lot SG26050703 |
| Wiley's Finest Peak EPA (figures from lot 124068, which expired 02/2021; no current lot is published) | 24.8 | 0.173 | All 4 compliant | 3.49 | lot 124068 |
IFOS limits: PCBs 45 ppb, dioxins and furans 1 ppt, TOTOX 19.5. California Gold Nutrition's iTested reports use different units and are compared on the heavy-metals page.
Not fish oil: krill oil has its own programme, IKOS. Which krill oils have a public IKOS lot report: the best third-party-tested krill oil.
FAQ
How do omega-3 supplements compare on purity and heavy-metal testing?
To compare omega-3 supplements on purity, read the certificate: of the 12 fish oils on this site, 10 publish an IFOS certificate with measured contaminants. All 10 are marked compliant for mercury, lead, cadmium and arsenic. Measured PCBs run from 0.245 ppb (OmegaVia EPA 500) to 24.8 ppb (Wiley's Finest Peak EPA, lot expired 02/2021) against the IFOS limit of 45 ppb, and TOTOX from 3.49 to 17.74 against 19.5. Read from each certificate on 2026-10-04.
Which fish oil has the lowest PCBs?
Of the IFOS-certified fish oils we track, OmegaVia EPA 500 at 0.245 ppb (lot OV250446, certificate read 2026-10-04), against an IFOS limit of 45 ppb.
How to verify any product in 30 seconds
- Find the product on our ranking table.
- Click the certificate link in its row.
- Check three things: measured EPA+DHA vs. the label claim, the TOTOX freshness number, and the heavy-metals section.
For one worked example, the Carlson The Very Finest Fish Oil certificate page shows all three for one tested lot: measured EPA+DHA against the label claim, TOTOX, and every heavy-metal result.
If a brand claims "third-party tested" but you can't find a certificate anywhere, that's a meaningful gap — and in our coverage work, a couple of well-known bestsellers fall into exactly that bucket.
This page explains published testing programs and makes no health, benefit, or treatment claims.