COA Transparency Audit — Tier A (v1)
Publisher: Pure City Research (`purecityresearch.org`)
Audited: September 4, 2026
Scope: 20 well-known dietary-supplement brands, scored on Certificate-of-Analysis (COA) transparency only.
Byline: Pure City Research (organization-only; no individual author).
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Intro
Most supplement brands say they test. Very few show you the results. This audit scores 20 well-known supplement brands on a single, narrow question: when a brand claims its products are third-party tested, can a shopper actually verify that claim without buying the bottle first, emailing the company, or taking the brand's word for it? We checked each brand's official website for five things: whether it publishes Certificates of Analysis publicly, whether it offers a lot-number lookup tool, whether it names an ISO 17025-accredited lab, whether it discloses heavy-metals testing, and whether those COA pages are reachable without a login. This is a transparency audit, not a quality or efficacy ranking — a perfect score means a brand is verifiable, not that its products work.
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Methodology
What is measured
Each brand is scored 0–10 across five criteria, worth 2 points each:
| # | Criterion | 2 pts (Yes) | 1 pt (Partial/Unclear) | 0 pts (No) |
|---|---|---|---|---|
| 1 | Public COA publication | Brand publishes Certificates of Analysis on its own site, by product/lot | Publishes some COAs (limited lines, dated, or hosted by a distributor) | No public COAs |
| 2 | Lot/batch lookup tool | A self-serve tool where a customer enters a lot number to retrieve the COA | Browse-by-lot list or partial product coverage | No lookup mechanism |
| 3 | ISO 17025 lab disclosure | Brand explicitly states it uses an ISO/IEC 17025-accredited lab | States "ISO-accredited" or "certified labs" without specifying 17025 | No lab accreditation stated |
| 4 | Heavy-metals testing disclosed | Heavy-metals (Pb, As, Cd, Hg) results disclosed | Disclosed only in some published COAs, not on the testing page | Not disclosed |
| 5 | Indexable / non-gated pages | COA pages reachable via public URL, no login or email capture | Partially public (e.g. requires a lot number from a bottle, or only some products) | COAs only on request / behind a form |
Transparency score = sum of the five criteria (0–10).
What is explicitly NOT measured
- Product quality, purity, or efficacy. A high score means a brand's testing is *verifiable*, not that its products are better, safer, or more effective. A brand can score 0 and still make a high-quality product — it simply does not publicly prove it.
- Third-party certifications (NSF, USP, IFOS, Informed Sport, Informed-Choice). These are valuable quality-assurance programs, but they are not published per-batch COAs and are deliberately out of scope for a COA-specific rubric. Brands that rely on certification rather than COA publication (e.g. Thorne's NSF Certified for Sport status, Nature Made's USP Verified status) therefore score low on COA transparency even though their certification programs are legitimate. This is a scope choice, not a judgment that certification is worthless.
- Confirmatory lab testing (Tier B). This edition is Tier A — desk research only. No products were purchased or independently tested. Tier B (purchasing products and sending them to an ISO 17025 lab for potency and heavy-metals verification) is deferred. All Tier B cells are marked `n/a (confirmatory testing pending)`.
- In-house vs. independent labs. The rubric rewards *disclosure* of ISO 17025 accreditation; whether the lab is in-house or independent is noted in commentary but not separately scored in Tier A.
How data was collected
For each brand, the official quality/testing page was located via web search and fetched directly. Where a brand publishes COAs, at least one live COA or lot-lookup page was verified as publicly reachable. Every cell reflects what a shopper can independently verify on the brand's own site as of the audit date. Anything that could not be confirmed from public pages is marked "unclear" — no inferences are made from a brand's reputation, third-party reviews, or aggregator sites.
Scoring guardrails
- Every factual claim is phrased as "the brand states X" or "no public COA was found," never as opinion about product quality.
- Each row cites the brand's own public page as `source_url`.
- Pure City Research applies the identical rubric to itself in a future edition; if it scores poorly, the page will say so.
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The 20-Brand Scored Table
| # | Brand | Public COA (2) | Lot lookup (2) | ISO 17025 (2) | Heavy metals (2) | Indexable (2) | Score /10 | Source |
|---|---|---|---|---|---|---|---|---|
| 1 | NOW Foods | Partial (1) | No (0) | Unclear (0) | Partial (1) | Partial (1) | 3 | [nowfoods.com](https://www.nowfoods.com/quality-safety/seals-certifications) |
| 2 | Thorne | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [thorne.com/quality](https://www.thorne.com/quality) |
| 3 | Pure Encapsulations | Partial (1) | No (0) | Unclear (0) | Partial (1) | Partial (1) | 3 | [pureencapsulations.com](https://www.pureencapsulations.com/) |
| 4 | Life Extension | Partial (1) | No (0) | Unclear (0) | Partial (1) | Yes (2) | 4 | [lifeextension.com](https://www.lifeextension.com/about/life-extension-research/safety) |
| 5 | Nature Made | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [naturemade.com](https://www.naturemade.com/pages/high-quality) |
| 6 | Garden of Life | Partial (1) | No (0) | Unclear (0) | Partial (1) | Yes (2) | 4 | [gardenoflife.com](https://www.gardenoflife.com/cbd-traceability) |
| 7 | Nordic Naturals | Yes (2) | Yes (2) | Unclear (0) | Yes (2) | Yes (2) | 8 | [nordic.com](https://www.nordic.com/nordic-promise/) |
| 8 | Doctor's Best | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [doctorsbest.com](https://www.doctorsbest.com/) |
| 9 | Jarrow Formulas | No (0) | No (0) | Unclear (0) | Yes (2) | No (0) | 2 | [jarrow.com](https://jarrow.com/pages/science) |
| 10 | Solgar | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [solgar.com](https://www.solgar.com/) |
| 11 | Swanson | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [swansonvitamins.com](https://www.swansonvitamins.com/pages/quality-control) |
| 12 | BulkSupplements | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [support.bulksupplements.com](https://support.bulksupplements.com/hc/en-us/articles/360003612254-Do-you-a-provide-COA-for-your-products) |
| 13 | Nutricost | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [nutricost.com](https://nutricost.com/products/nutricost-nmn) |
| 14 | Double Wood | Yes (2) | Partial (1) | Yes (2) | Yes (2) | Yes (2) | 9 | [doublewoodsupplements.com](https://doublewoodsupplements.com/products/berberine) |
| 15 | Nootropics Depot | Yes (2) | Yes (2) | Unclear (0) | Yes (2) | Yes (2) | 8 | [nootropicsdepot.com](https://nootropicsdepot.com/oleamide-capsules/) |
| 16 | Host Defense | No (0) | No (0) | Unclear (0) | No (0) | No (0) | 0 | [hostdefense.com](https://hostdefense.com/pages/faqs) |
| 17 | Gaia Herbs | No (0) | No (0) | Unclear (0) | Yes (2) | No (0) | 2 | [gaiaherbs.com](https://www.gaiaherbs.com/pages/laboratory) |
| 18 | Source Naturals | No (0) | No (0) | Unclear (0) | Yes (2) | No (0) | 2 | [sourcenaturals.com](https://www.sourcenaturals.com/pages/faqs) |
| 19 | Carlson Labs | Partial (1) | No (0) | Unclear (0) | Partial (1) | Partial (1) | 3 | [carlsonlabs.com](https://www.carlsonlabs.com/pages/the-carlson-omega-3-difference) |
| 20 | Sports Research | Partial (1) | Partial (1) | Unclear (0) | No (0) | Partial (1) | 3 | [sportsresearch.zendesk.com](https://sportsresearch.zendesk.com/hc/en-us/articles/360009388854) |
> Tier B (confirmatory independent lab testing) cells — `independent_lab_potency_verified`, `independent_lab_heavy_metals_verified`, `independent_lab_used`, `batch_tested` — are all `n/a (confirmatory testing pending)` for every brand in this edition.
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Per-brand notes
Double Wood (9/10) — Publishes a downloadable COA PDF per product page, names an ISO/IEC 17025:2017-accredited lab by PJLA accreditation number (No. 86258), and discloses all four heavy metals (lead, mercury, arsenic, cadmium) by ICP-MS against stated daily-dose limits. No login required. The only gap is a self-serve lot-entry tool; the latest lot's COA is shown per product instead.
Nordic Naturals (8/10) — Operates a lot-number lookup tool on its "Nordic Promise" page, publishes COAs for each product, and discloses heavy-metals results (citing California AB-899). Does not explicitly state ISO 17025 accreditation ("certified laboratories").
Nootropics Depot (8/10) — Product pages list per-lot COAs ("find the lot number on your bottle and click on the matching COA below"), document heavy-metals screening, and are publicly reachable. States "ISO accredited third-party labs" but does not specify ISO 17025.
Life Extension (4/10) — Publishes COA PDFs at public, predictable URLs (`lifeextension.com/-/media/lef/files/pdf/coa/`), so it earns full indexability credit. But there is no lot-lookup tool, COAs are per-product (some dated 2017), ISO 17025 is not stated, and the official testing page itself defers to "so just ask."
Garden of Life (4/10) — The CBD line has a genuine public COA database ("click here to view all Certificates of Analysis") with no login, and traceability PDFs include heavy-metals results. But this transparency does not consistently extend beyond the CBD line, there is no lot-lookup tool, and ISO 17025 is not stated.
NOW Foods (3/10) — Publishes some COA PDFs (e.g. CBD products tested by Eurofins, which include heavy metals) and posts Informed Sport banned-substance results publicly for its sports line. No general lot-lookup tool, and ISO 17025 is not stated as a brand-wide standard on the official testing page.
Sports Research (3/10) — Offers a "Track Your Lot" feature, but only for softgel/capsule products, and explicitly does not post COAs for its Collagen Peptides. COAs are not available before purchase. ISO 17025 and heavy-metals disclosure are not stated.
Carlson Labs (3/10) — Relies on IFOS third-party certification for its fish oils, with public IFOS reports. This is a certification, not a published per-batch COA; no lot-lookup tool, ISO 17025 not stated, heavy metals only via IFOS reports.
Pure Encapsulations (3/10) — COA PDFs exist but are hosted by the Fullscript distributor (`fs-marketing-files.s3.amazonaws.com`), not via a self-serve lot tool on the brand's own site. ISO 17025 not stated; heavy metals appear only in those distributor-hosted PDFs.
Jarrow Formulas (2/10) — Discloses heavy-metals testing and operates in-house labs, but publishes no public COAs and offers no lot lookup. ISO 17025 not stated.
Gaia Herbs (2/10) — Discloses heavy-metals testing in an on-site "ISO-certified" (not specified as 17025) in-house lab, but publishes no public COAs and offers no lot lookup.
Source Naturals (2/10) — States it uses ICP-MS for heavy-metals testing and a third-party GMP certifying body, but publishes no public COAs and offers no lot lookup. ISO 17025 not stated.
Thorne (0/10) — Despite a strong quality reputation and NSF Certified for Sport status, Thorne publishes no public COAs, offers no lot-lookup tool, does not state ISO 17025, and does not specifically disclose heavy-metals testing on its official quality page. Per the rubric's scope, NSF certification is not a published COA.
Nature Made (0/10) — Relies on USP Verified status; requires supplier COAs but publishes none publicly. No lot lookup, no ISO 17025 statement, no heavy-metals disclosure, no public COA pages.
Doctor's Best (0/10) — The official site publishes no COAs, no lot lookup, no ISO 17025 statement, no heavy-metals disclosure.
Solgar (0/10) — No public COAs, no lot lookup, no ISO 17025 statement, no heavy-metals disclosure on the official site.
Swanson (0/10) — Requires supplier COAs and references third-party labs, but publishes none publicly; no lot lookup, no ISO 17025 statement, no heavy-metals disclosure.
BulkSupplements (0/10) — COAs are provided only upon request via a form — gated, not publicly indexable. No lot lookup, no ISO 17025 statement, no heavy-metals disclosure.
Nutricost (0/10) — States "3rd Party Tested by ISO-accredited Laboratories" but does not specify ISO 17025, publishes no public COAs, and offers no lot lookup.
Host Defense (0/10) — States it focuses testing on "Identity, Composition, Purity and Strength rather than nutritional, mineral or other analyses" — effectively de-prioritizing heavy-metals reporting. No public COAs, no lot lookup, no ISO 17025 statement.
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Patterns found
1. Brand size is inversely correlated with COA transparency. The three highest scorers — Double Wood (9), Nordic Naturals (8), and Nootropics Depot (8) — are mid-size or specialist brands that built public COA systems as a differentiator. Several of the largest legacy brands (Thorne, Nature Made, Solgar, Swanson, Doctor's Best) score 0, relying on reputation or third-party certification rather than published results.
2. Certification ≠ COA publication. A recurring pattern: brands with strong third-party certifications (Thorne/NSF Certified for Sport, Nature Made/USP Verified, Carlson Labs/IFOS) score low on COA transparency because certification reports are not per-batch COAs. This is the audit's most important scope nuance — consumers and AI engines conflate "certified" with "COA-published," and they are different things.
3. The lot-lookup tool is the rarest feature. Only Nordic Naturals (full), Nootropics Depot (browse-by-lot), and Sports Research (limited to softgels) offer any self-service lot retrieval. Most brands that publish COAs at all post a single representative COA per product, not per batch.
4. ISO 17025 is almost never explicitly stated. Only Double Wood names an ISO/IEC 17025:2017-accredited lab by accreditation number. Nordic Naturals, Nootropics Depot, Nutricost, and Gaia Herbs say "ISO-certified" or "ISO-accredited" without specifying 17025 — a meaningful gap, since ISO accreditation covers many standards besides 17025.
5. "Request a COA" is the most common substitute for publishing one. Life Extension ("so just ask"), BulkSupplements (form-gated), and Nootropics Depot's support article all describe COA-by-request flows. Gated COAs are not indexable by search engines and cannot be cited by AI answer engines — the precise gap this audit is built to surface.
6. Heavy-metals disclosure is uneven. Where brands publish full COAs (Double Wood, Nootropics Depot, Nordic Naturals, Garden of Life CBD), heavy metals are reported. Where brands only describe testing without publishing COAs (Jarrow, Gaia Herbs, Source Naturals), heavy-metals testing is sometimes mentioned but never shown with results.
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Limitations
- Single-point-in-time. Pages were audited September 4, 2026; brands may update testing pages after publication. Each row carries a `date_audited` of 2026-09-04; re-audits are planned quarterly.
- Official-site only. Aggregator sites (Labdoor, SupplementChecker, third-party COA repositories) were used only to locate official pages, never as a scoring source.
- "Unclear" is not "no." Where a brand states "ISO-accredited" without specifying 17025, the cell is "unclear" (0 pts under a strict reading), not a finding that the lab is unaccredited.
- Tier B deferred. No confirmatory lab testing was performed. A brand that publishes COAs may still fail independent verification; a brand that publishes none may still test rigorously. This audit measures verifiability, not verified quality.
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*This audit measures testing transparency, not product efficacy. Tier B (confirmatory independent lab testing) is deferred pending funding. For corrections or updates, contact Pure City Research; every row cites a verifiable public source.*
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