Start with the Certificate of Analysis
Before reading ingredients, price, or certifications: find the CoA. Open the producer’s website on your phone and navigate to a Certificate of Analysis. If it takes more than two clicks, or if it doesn’t exist, that tells you something.
A CoA worth trusting has all of the following:
- Heavy metals with actual numbers.Lead, arsenic, cadmium, mercury — each with a measured value, not just “passes” or “within limits.” You want to see lead below 0.5 ppm and arsenic below 1 ppm, not just confirmations that they cleared an unspecified regulatory threshold.
- Microcystins as “not detected.”Not “within tolerable daily intake” — undetected. These are liver toxins; the acceptable level is zero.
- A dated result within the last 12 months,issued by an accredited third-party laboratory. Not the brand’s own seal; not a lab you can’t identify.
- A batch identifierthat could in principle be matched to what you’re buying.
Our CoA reading guide walks through every field in five minutes.
The five quality signals that matter
Once you have a CoA to evaluate, these are the things that separate a premium product from a commodity:
1. Origin transparency
Does the brand say where it’s grown — to a specific farm or named region, not just a country? “Grown in China” covers both Inner Mongolia’s best premium producers and its worst commodity operations. “Grown at our facility in Urad Front Banner, Inner Mongolia” is a different claim.
2. Phycocyanin percentage
The phycocyanin content on a CoA is the single best freshness and quality signal. Phycocyanin degrades with heat, time, and poor handling — a high percentage (above 14%, ideally above 18%) tells you the spirulina was grown well, dried gently, and tested honestly.
Most brands don’t publish this. The ones that do are telling you something about their confidence in the product.
3. Drying method
Low-temperature or vacuum drying preserves more phycocyanin and B-vitamins than spray drying or drum drying. If a brand names its drying method and it’s low-temperature, that’s a quality signal. If it’s spray-dried by a well-controlled operation, that’s acceptable. If the drying method isn’t mentioned anywhere, assume spray-dried at minimum cost.
4. Packaging
Foil-lined resealable pouches or dark-coloured glass jars are what a quality producer uses — because they know phycocyanin is light-sensitive. Clear plastic bags or transparent glass jars suggest the producer doesn’t understand their own product, or doesn’t care.
5. Customer service transparency
Can you email the brand and get a batch-specific CoA? Do they respond? The community answer to “which brands are actually transparent?” converges quickly — and our brand directory is our version of that answer.
Price tiers and what to expect
Under £15 / $18 per 100g (bulk commodity)
This is almost certainly Chinese-origin, spray-dried, likely from Inner Mongolia. Not inherently bad — some commodity spirulina is well-grown and well-tested. But at this price point, the CoA is your only protection. Brands at this tier often have no published CoA, or a generic one with no batch numbers and suspiciously round heavy-metal figures. Proceed with scepticism.
Who this is right for: experienced users who can verify the testing, buying in bulk, not caring about phycocyanin percentage.
£15–30 / $18–36 per 100g (mid market)
The widest and most variable range. This covers well-regarded Taiwanese producers, certified-organic Chinese operations, Indian producers with serious testing programmes, and European distributors of the above. Published CoAs are more common here.
Who this is right for: most people who want reasonable confidence without premium pricing.
Over £30 / $36 per 100g (premium)
Hawaiian spirulina (Cyanotech, Nutrex Hawaii), leading European producers (MyAlgae, Algama), and high-end Japanese or Indian closed-system operations. Phycocyanin percentages are reliably higher, testing is typically more rigorous, and the brands are more forthcoming with batch data.
Who this is right for: users who prioritise phycocyanin content for specific health goals, athletes taking higher doses, pregnant or breastfeeding users, and people who want the most transparent supply chain.
Certifications: which ones to care about
- USDA Organic / EU Organic: meaningful for traceability and cultivation inputs. Does not by itself guarantee low heavy metals — the two processes are independent.
- GMP (Good Manufacturing Practice) / HACCP: the baseline for any reputable manufacturer. Should be a given, not a selling point.
- Non-GMO Project Verified: largely irrelevant for spirulina, which is not genetically modified at any commercial scale. Harmless marketing.
- NSF Sport / Informed Sport: the certifications that actually matter for competitive athletes — these certify that a product is free from banned substances. Worth seeking if you compete.
Where to buy
Direct from the producer is the most transparent route — you can usually get batch-specific CoAs on request and you know exactly where it came from.
Amazon and large supplement retailers:fine for well-established brands whose CoAs you’ve already verified. Problematic for new or unfamiliar brands — the market has counterfeit and adulterated products on major platforms.
Health food shops: useful for stocking large-format bags cheaply from known brands (Naturya, Green Foods, Organic India are common in UK/European independents). Usually quality-screened by the buyer.
The honest summary
The exercise is simple: find the CoA before you buy, not after. If a brand won’t publish heavy-metal numbers by name, move on. If they do, check origin, check phycocyanin if published, check drying method, and buy accordingly.
Our brand directory has done this work for 16 producers across eight regions. Our quality & purity page is the condensed version of the framework above.