Every reputable spirulina producer publishes a Certificate of Analysis (CoA) for their current batches. Most people who buy spirulina have never read one. This is a quick walk through what one looks like and which fields actually carry information.
What a CoA is
A CoA is a one- or two-page document from an accredited testing laboratory listing the measured properties of a specific batch of product. It is a statement of fact, not marketing, and it is the only document on a producer’s website that makes a verifiable claim.
The version published on a producer’s website should:
- Be dated within the last 12 months;
- Identify a specific batch number that matches the product you can buy;
- Be issued by a third-party lab (the producer’s own internal lab carries near-zero regulatory weight);
- Print results as numbers, not as “pass / fail”.
The five fields that matter
1. Heavy metals (mg/kg)
Lead, arsenic, cadmium, mercury — listed as numbers, often with regulatory limits in an adjacent column. The bar to clear is not “within limits.” It is well below limits, ideally an order of magnitude under. A premium spirulina is typically <0.1 mg/kg lead, <0.05 mg/kg cadmium and arsenic.
If a CoA says “within USP/EP limits” without a number, that’s a half-disclosure. Better than nothing, but you don’t know what the actual margin is.
2. Microcystins (μg/g)
The most important number on the page if you’re pregnant. Microcystins are liver-toxic peptides produced by some cyanobacteria; well-grown spirulina is uncontaminated by them. The result you want is “not detected” with a stated detection limit (typically 0.05 or 0.1 μg/g). “Below tolerable daily intake” is a weaker claim — there’s no good reason a clean batch should have any.
3. Phycocyanin content (%)
The single best signal of freshness, gentle drying, and overall quality. Read by tier:
- > 18% — premium / very fresh, vivid colour, often air- or vacuum-dried.
- 14–18% — good quality, well-processed.
- 10–14% — acceptable, often the bulk-market norm.
- < 10% — older, over-heated, or stored badly.
Most producers don’t print this number. Brands that do are signalling confidence in their drying process.
4. Microbial panel
Total plate count (TPC), yeasts & moulds, coliforms, E. coli, salmonella. Standard food-safety panel. Should all be either “not detected” (the pathogens) or within strict limits (counts).
5. Protein and ash content (%)
Less critical for safety but useful for quality calibration. Healthy spirulina is 60–70% protein and 6–10% ash (mineral content) by dry weight. Numbers wildly outside these ranges suggest issues with the cultivation — under-protein typically means a stressed culture or excessive carbon-fixing additive use.
What you can ignore
- “Tested for purity.” Means almost nothing legally; says even less.
- The producer’s own self-certified seal.
- “Non-GMO” — spirulina is never genetically modified at any commercial scale; this is a default condition, not a quality marker.
- Fancy logos with “laboratory verified” copy that doesn’t name an actual lab.
The 30-second test
Open the producer’s website on your phone right now. Can you find a CoA in two clicks? Does it have a recent date and a specific batch number? Does it list heavy metals with numbers, not “pass”? Does it report microcystin as “not detected”? Three or more “yes”s and you’re looking at a serious product. One or zero and you’re looking at marketing.
For a deeper read on what makes good spirulina good, see quality & purity.