How to Read a Supplement COA

Every serious buyer asks for a Certificate of Analysis. Far fewer know how to read one — and a COA that is not read is just a PDF. Here is what each section means, what the numbers should be, and the signs that a COA is not worth the paper.

What a COA is, and is not

A COA is a report of test results on a specific batch (lot) of a specific product, issued by the factory’s lab or a third-party lab. It says: this lot, tested on this date, contained these amounts of these things, against these specifications. It is not a certificate of quality in general, not a GMP certificate, and not valid for a different lot or count.

The header: what to check first

• Product name and lot number — must match the bottle in your hand.
• Manufacture and test dates — recent, and after the lot was made.
• Lab — the factory’s QC lab (routine) or a named third-party lab (ISO 17025 accreditation for US platform submissions).
• Specification column — every result should sit next to a limit. A COA with results but no specs tells you nothing.

Section 1: identity and appearance

Confirms the product is what it claims: description (colour, form, odour), identity test for key actives (FTIR, HPTLC for botanicals), average unit weight, count. For gummies, piece weight ±5%; for capsules, fill weight ±5%.

Section 2: potency (assay)

The amount of each declared active per serving, measured by HPLC, ICP-MS (minerals) or a validated method, compared with the label claim. Typical acceptance is 90–120% of label for most actives; some vitamins allow wider ranges because of overage built in to cover shelf life. Watch for: actives listed on the label but missing from the assay, or “complies” without a number.

Section 3: heavy metals

Lead, arsenic, cadmium, mercury, reported in mcg per daily serving or ppm. Reference limits: USP <2232> (per daily dose) and, for products sold in California, Proposition 65 thresholds (lead 0.5 mcg/day is the well-known one). Botanicals, minerals and shilajit are the categories where this section matters most; a shilajit COA without heavy metals is a reason not to buy.

Section 4: microbial

Total aerobic count, yeast and mold, E. coli, Salmonella, sometimes Staphylococcus aureus. Limits per USP <2021>/<2022>: for a typical supplement, total aerobic count ≤ 10⁴ CFU/g, yeast and mold ≤ 10³ CFU/g, E. coli and Salmonella absent. Pet products: Salmonella absent is a release criterion, not a periodic check.

Section 5: format-specific tests

• Gummies — water activity (aw). The predictor of mold and texture drift. Look for ≤ 0.65. Also pH for pectin gummies (3.2–3.6) and moisture.
• Softgels and oils — peroxide value and anisidine value. Together they give TOTOX; low numbers mean fresh oil. For fish oil, PV ≤ 5 meq/kg and TOTOX ≤ 26 are common quality targets.
• Capsules and tablets — disintegration. ≤ 30 minutes for capsules; hardness and friability for tablets.
• Liquids — pH, density, fill volume. pH matters for preservative efficacy.
• Powders — moisture, bulk density.

Red flags

• No lot number, or a lot number that does not match the product.
• Results without specifications, or every line reading “complies” with no figures.
• Heavy metals or microbial missing entirely.
• A COA dated before the batch could have been made.
• The same COA offered for different products or counts.
• A “COA” that is actually the raw-material supplier’s certificate, not a finished-product test.

Factory COA vs third-party COA

A factory QC lab COA is standard and sufficient for most purposes; it is issued with every batch here. A third-party COA from an accredited lab is independent verification — worth it for your hero SKU, for platform submissions that require it, and for any product where a buyer will publish the COA on the product page (shilajit, mushrooms, kids’ products). We arrange US lab testing at cost on request.

How to use a COA as a selling tool

Publish it. A product page with a downloadable COA — lot-specific, with heavy metals and potency — converts better than one without, especially in categories with trust problems. Ask your factory for a customer-facing version with the batch number and results; ours are issued that way by default. See compliance for a sample.