Buyer's Guide

How to Read a Supplement Certificate of Analysis (COA)

The COA is the most important document in functional supplement quality verification. Here's what every section means and what red flags to watch for.

Published 2025-02-01 · Updated 2026-06-01 · 8 min read

The short answer

A Certificate of Analysis (COA) is a third-party lab report that verifies what's actually in a supplement. For mushroom supplements, a quality COA confirms beta-glucan content (not just total polysaccharides), starch levels (a proxy for grain filler), and heavy metal safety. Cogniscore requires COA verification for any brand to score above 6/10 on Transparency. Without a COA, a brand's label claims are unverified.

What Is a Certificate of Analysis?

A Certificate of Analysis (COA) is an analytical document produced by a testing laboratory that certifies the contents of a specific batch (lot) of a product. For dietary supplements, COAs are the primary evidence that a product contains what it claims—at the concentration claimed—and is free from unsafe levels of contaminants.

Unlike FDA drug manufacturing (where testing is mandated), dietary supplement COA testing is voluntary—brands choose whether to test and whether to share results. This is why COA availability is such a strong signal of brand trustworthiness.

Step-by-Step: How to Read a Mushroom Supplement COA

1

Confirm the lab is a third party

The COA should be issued by an independent laboratory, not the manufacturer's own lab. Look for a lab name different from the brand, and verify ISO 17025 accreditation. Common accredited labs: Eurofins, Covance, NSF International, ChromaDex.

✓Lab: Eurofins Scientific (ISO 17025 Accredited)
✗Lab: BrandName Quality Department
2

Match the batch/lot number to your product

Every valid COA has a batch or lot number that matches the product you're buying. If a brand shows you a single COA for all products with no batch number, the testing may not reflect current production.

✓Lot: LM-2026-0413-FB
✗No lot number listed
3

Find the beta-glucan test result

This is the most important number for mushroom supplements. Look for 'beta-glucan' or 'β-glucan'—not just 'polysaccharides.' The result should be expressed as a percentage (% w/w). For lion's mane, look for 25%+.

✓Beta-glucan content: 28.4% (Method: Megazyme K-BGLU)
✗Total polysaccharides: 40% (no beta-glucan breakdown)
4

Check starch content

Starch content reveals grain filler in mycelium-on-grain products. Quality fruiting body extracts should have less than 5% starch. Results above 15% strongly suggest mycelium-on-grain.

✓Starch content: 3.1%
✗Starch content: 48.7% (or: starch not tested)
5

Review heavy metal results

Mushrooms bioaccumulate heavy metals. A full heavy metal panel should include Lead (Pb), Arsenic (As), Cadmium (Cd), and Mercury (Hg). Compare to Prop 65 or USP limits per serving size.

✓Pb: <0.10 ppm | As: <0.25 ppm | Cd: <0.15 ppm | Hg: <0.01 ppm
✗Heavy metals: not tested / not listed
6

Check microbial testing

A complete COA includes microbial safety testing: Total Aerobic Count, Yeast & Mold, E. coli, and Salmonella. These should all show results below established safety limits.

✓Salmonella: Absent/25g | E. coli: <10 CFU/g
✗Microbial: not tested

⚠ Red Flags: When to Be Concerned

  • •COA tests 'polysaccharides' but not 'beta-glucans' specifically
  • •COA is from the manufacturer's own testing department
  • •No batch/lot number on the COA
  • •Starch content above 15% in a supposed fruiting body product
  • •Heavy metal or microbial testing absent from a wildcrafted mushroom product
  • •Brand refuses to provide COA or points to an expired one (>12 months old)
  • •COA lab is not ISO 17025-accredited

How Cogniscore Uses COAs in Scoring

COA verification is the backbone of Cogniscore's Transparency dimension (30% of total score). Our process:

  1. Request or locate the COA for each product batch reviewed.
  2. Verify the testing laboratory's accreditation status via national accreditation body databases.
  3. Cross-reference the label claim against the COA result for beta-glucan content, active compound content, and starch levels.
  4. Note discrepancies—if a label claims "30% polysaccharides" but the COA shows only 4% beta-glucan, we flag this as a label mismatch.
  5. Check heavy metal compliance against California Prop 65 limits as a conservative reference standard.

Brands that score 9–10/10 in Transparency provide batch-specific COAs proactively on their website, test for all relevant active compounds, disclose starch content, and pass all heavy metal and microbial thresholds.

COA Questions Answered

What is a Certificate of Analysis for supplements?+
A Certificate of Analysis (COA) is a document from a third-party laboratory that verifies the contents of a supplement batch. It lists test results for active compound content (e.g., beta-glucans, withanolides), contaminants (heavy metals, pesticides, microbes), and confirms that the product matches its label claims. A COA is the gold standard for supplement quality verification.
How do I verify a mushroom supplement COA?+
Request the COA from the brand (either publicly posted or via email). Check that: (1) It comes from a third-party lab, not the manufacturer; (2) The lab is ISO 17025-accredited; (3) The batch number on the COA matches the product you're buying; (4) Beta-glucan content is specifically listed (not just polysaccharides); (5) Heavy metal tests (lead, arsenic, cadmium, mercury) are included and pass established limits.
What should a good mushroom supplement COA include?+
A complete COA should include: batch/lot number, test date, active compound analysis (beta-glucan %, and for reishi: triterpene %; for cordyceps: cordycepin %), starch content (to confirm absence of grain filler), heavy metal panel (Pb, As, Cd, Hg), microbial testing (total plate count, yeast & mold, E. coli, Salmonella), and pesticide residue testing. The laboratory should be ISO 17025-accredited.
What does it mean if a brand won't share their COA?+
Brands that refuse to share COAs typically have something to hide—usually poor active compound content, high starch levels in mycelium-on-grain products, or contaminant issues. Cogniscore treats COA refusal as a major Transparency deduction and caps those brands' scores at 5.5/10 regardless of other factors.
What are red flags on a supplement COA?+
Red flags include: polysaccharides tested but beta-glucans not separately quantified; starch content above 5% in supposed fruiting body extracts; heavy metal results near or above FDA/USP limits; the COA is from the manufacturer's own lab rather than a third party; the COA is undated or missing a batch number; the lab is not ISO 17025-accredited.
How does Cogniscore use COAs in scoring?+
COA verification is the single largest component of Cogniscore's Transparency dimension (30% of total score). Brands with publicly accessible, batch-specific COAs from ISO 17025-accredited labs score 8–10/10 in Transparency. Brands with no COA available score 2–4/10. Brands with COAs that don't test beta-glucans specifically score 5–6/10.
What are safe heavy metal limits for mushroom supplements?+
Cogniscore uses the California Prop 65 limits as a conservative reference: Lead (Pb): <0.5 μg/day; Arsenic (As): <10 μg/day; Cadmium (Cd): <4.1 μg/day; Mercury (Hg): <0.3 μg/day. Mushrooms are bioaccumulators, so heavy metal testing is non-negotiable—especially for chaga and any wildcrafted mushrooms.

Sources & References

  • FDA (2024). Dietary Supplement Current Good Manufacturing Practice regulations. fda.gov
  • California OEHHA (2024). Prop 65 Safe Harbour Levels. oehha.ca.gov
  • USP (2024). Chapter <2232> Elemental Contaminants in Dietary Supplements.
  • Consumer Labs (2022). Mushroom Supplement Review — independent testing methodology.
  • Cogniscore (2026). Internal COA verification methodology and scoring rubric.
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Information on this platform relates to nutritional composition and public disclosure practices only. It is not medical advice. No claims are made about the therapeutic efficacy, safety, or suitability of any product. Always consult a qualified healthcare professional before taking any supplement.