Matcha Brands with Published COA

Why these brands qualify

Each brand publishes at least one COA with numeric results from a named laboratory. COA status is verified from brand websites at the time of last verification.

Useful for

Safety-conscious buyers who want to verify heavy metal levels before purchasing, researchers comparing brand transparency, and anyone who wants to see actual lab numbers rather than marketing claims.

Strongest in collection

Teafy — Publishes numeric COA (ppb resolution, named lab, dated)

What Is a Certificate of Analysis (COA)?

A Certificate of Analysis (COA) is a document issued by an accredited laboratory that reports the measured levels of specific substances in a tested sample. For matcha, a meaningful COA reports heavy metal levels (lead, cadmium, arsenic, mercury) in parts per billion (ppb), names the testing laboratory, and includes the test date. A COA is the primary tool for verifying a brand's safety claims.

Why COAs Matter for Matcha Safety

Matcha is a concentrated whole-leaf powder, meaning any contaminants in the leaf are concentrated in the final product. Heavy metals — particularly lead and cadmium — can accumulate in tea plants from soil. Without a published COA, there is no way to verify a brand's safety claims. A COA lets you compare actual measured values against regulatory limits (e.g., California Prop 65 limits for lead).

How to Read a Matcha COA

A meaningful COA should include: (1) the name of the accredited testing laboratory, (2) the test date, (3) the specific product or batch tested, (4) numeric values for lead, cadmium, arsenic, and mercury in ppb or mg/kg, and (5) the detection limits. Be cautious of COAs that only show 'non-detect' without specifying the detection limit — a non-detect at 1 ppm is very different from a non-detect at 1 ppb.

COA vs. Testing Claim: The Difference

Many brands claim to test their matcha without publishing the results. This is not equivalent to a published COA. A testing claim without published numbers cannot be independently verified. We classify brands that claim testing without publishing results as Tier 3 — meaningfully different from brands that publish actual COA data publicly.

What is the difference between a brand COA and an independent test?

A brand COA is commissioned and published by the brand itself. An independent test is conducted by a third party (e.g., a consumer advocacy organization or independent lab) without brand involvement. Both are valuable, but independent tests provide an additional verification layer since the brand doesn't control the results.

What heavy metal limits should I look for in a matcha COA?

California Prop 65 sets a maximum allowable dose level (MADL) for lead of 0.5 micrograms per day. For a typical 2g serving of matcha, this translates to approximately 250 ppb lead in the powder. Most high-quality matcha brands publish lead levels well below this threshold. The FDA's action level for lead in food is 100 ppb for certain categories.

How often should a brand update their COA?

Ideally, brands should publish a new COA for each production batch, since heavy metal levels can vary between batches from different farms or harvest seasons. At minimum, annual COA updates are a reasonable expectation. Check the test date on any COA — results from several years ago may not reflect current product.

Can I trust a COA that only shows 'non-detect'?

It depends on the detection limit. A non-detect result is only meaningful if the detection limit is specified and is at ppb resolution. A non-detect at 1 ppm (1,000 ppb) cannot rule out contamination at the ppb level. Always check the detection limit alongside the non-detect result.