Is Your Spirulina Clean? The Toxin Scare Is a Different Algae

Buy Zazzee Organic Spirulina Powder

Zazzee says a lab tests it for microcystin and heavy metals. It is also the cheapest we found: $0.12 per 3 g.

Buy on Amazon

• Want to know where it was grown? Nutrex Hawaii Pure Hawaiian Spirulina Powder says it is grown and made in Kona, Hawaii. It names no toxin test and costs $0.31 per 3 g.
• Prefer tablets? Nutrex Hawaii Pure Hawaiian Spirulina Tablets are the same Hawaii spirulina; 6 tablets make 3 g.

Names what it tests for (1)

No lab or report is named.

1. 

   Our pick

   Zazzee Organic Spirulina Powder

   Says: tested for microcystin and heavy metals

   Grow site not stated

   $0.12 per 3 g

   Buy on Amazon

Says “tested” but not what for (4)

These say “tested” or “verified” but do not name the toxins or metals.

1. 

   Micro Ingredients Organic Spirulina Powder

   Says: “3rd-party lab tested”

   Grow site not stated

   $0.15 per 3 g

   Buy on Amazon
2. 

   KOS Organic Spirulina Powder

   Says: “third-party tested”

   Grow site not stated

   $0.28 per 3 g

   Buy on Amazon
3. 

   Grown in Hawaii

   Nutrex Hawaii Pure Hawaiian Spirulina Powder

   Says: “USP Verified” (we could not confirm it)

   Grown in Kona, Hawaii

   $0.31 per 3 g

   Buy on Amazon
4. 

   Tablets

   Nutrex Hawaii Pure Hawaiian Spirulina Tablets

   Says: “USP Verified” (we could not confirm it)

   Grown in Kona, Hawaii

   $0.49 per 3 g

   Buy on Amazon

No outside testing claim (3)

No word on outside testing on the product page.

1. 

   BulkSupplements Organic Spirulina Powder

   No outside testing claim

   Grow site not stated

   $0.28 per 3 g

   Buy on Amazon
2. 

   NOW Organic Spirulina Powder

   No outside testing claim

   Grow site not stated

   $0.30 per 3 g

   Buy on Amazon
3. 

   NOW Organic Spirulina Tablets

   No outside testing claim

   Grow site not stated

   $0.55 per 3 g

   Buy on Amazon

Cost is per 3 g at each brand’s own price (October 18, 2026); Amazon’s can differ. Claims and grow sites are from each brand’s page.

The toxin scare is about wild algae

Microcystin is a liver toxin made by some blue-green algae. Labs found it in supplements made from wild blue-green algae (AFA), not in spirulina (Heussner 2012; Vichi 2012). One study found up to 5.2 micrograms per gram in AFA (Vichi 2012). In cell tests, extracts of every product, spirulina included, harmed cells; what that means for people is not known (Heussner 2012). Check that your label says spirulina or Arthrospira, not AFA or Aphanizomenon.

What about heavy metals?

One study of store spirulina found mercury within safe limits but did not test lead, arsenic or cadmium (Al-Dhabi 2013). A brand that names its metal tests, or its farm, gives you more to go on.

“Tested” on a label is not a listing

KOS and Micro Ingredients say “third-party tested” without naming a lab or what was tested. Nutrex Hawaii’s page says “USP Verified,” but we could not find it on USP’s list. You cannot check claims like these.

How to check your own tub

1. Make sure the label says spirulina or Arthrospira, not AFA or blue-green algae from a lake.
2. Look for named tests: microcystin, lead, arsenic, cadmium and mercury.
3. Ask the brand for the lab report (certificate of analysis) for your batch.

Questions people ask

Sources

1. Heussner AH, et al. “Toxin content and cytotoxicity of algal dietary supplements.” Toxicol Appl Pharmacol. 2012. PubMed 23064102
2. Vichi S, et al. “Contamination by Microcystis and microcystins of blue-green algae food supplements.” Food Chem Toxicol. 2012. PubMed 23036452
3. Al-Dhabi NA. “Heavy metal analysis in commercial Spirulina products for human consumption.” Saudi J Biol Sci. 2013. PubMed 24235875
4. Testing claims and grow sites from each brand’s own page, read October 18, 2026. Testing lists searched September 22, 2026.