Toxins in Blue-Green Algae, Like Klamath Lake AFA (Aphanizomenon flos-aquae)

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Why do I recommend staying away from blue-green Algae?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Schizochytrium, the type of algae used to make algae-based DHA supplements is grown under controlled conditions and has been found to be free of marine biotoxins. The same can’t be said for blue-green algae products, like AFA, Aphanizomenon flos-aquae, a blue-green algae harvested from Klamath Lake in Oregon and marketed as a dietary supplement.

Studies have shown this blue-green algae can produce significant levels of cylindrospermopsin and saxitoxin. Cylindrospermopsin is a liver toxin and saxitoxin is a neurotoxin, listed as a Schedule 1 substance in the Chemical Weapons Convention. The first big exposé of AFA was published in 2000, with microcystin liver toxins found in 85 of 87 samples, 72 percent exceeding Oregon State’s safety limit of one part per million, which is based on an average adult weighing 60 kg (about 132 pounds) and consuming about 2 grams a day.

AFA has the toxigenic genes that produce these microcystins directly, but when you’re harvesting it outdoors, it is almost impossible to avoid the presence of other algae species that can produce toxins too. Since their release on the market and after some public inquiries about adverse health effects of these products, the producers of the Klamath Lake blue-green algae products have repeatedly claimed that their products are safe. Well…okay, maybe not safe, but at least has toxin contamination below the regulatory limit.

In 2018, dozens of blue-green algae products containing AFA were tested, and about a quarter were close to, or over, the regulatory limit, though only one Klamath lake powder significantly exceeded the limit at nearly 3 parts per million. But in 2020, two AFA supplements tested at closer to 50 parts per million. At the recommended doses, that could present up to 75 times the tolerable daily intake. When those two off-the-charts contaminated brands were tested in the 2018 survey, they only had down about the limit. This confirms that there is a potential for great variability between lots of AFA harvested from Klamath Lake. So even if a supplement company claims their brand tested under the limit, you never know what their next bottle is going to contain. Other studies have shown up to the same 50-fold variability among batches of the very same brand.

There was even a case reported of a young woman who died of liver failure tentatively attributed to the prolonged consumption of toxic AFA supplements, given the levels of the toxins the researchers were able to pick up in the liver on autopsy. In light of the findings, the distribution and commercial sale of AFA blue-green algae products for human consumption appear highly questionable. And the irony is that they are commonly consumed for purported “detoxification.”

Here’s the latest: In 2023, Klamath Lake AFA continues to be contaminated with up to ten times the upper safety limit. To minimize exposure to these toxins, the researchers suggest using spirulina or chlorella-based products instead. But are they any safer? We’ll find out next.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Schizochytrium, the type of algae used to make algae-based DHA supplements is grown under controlled conditions and has been found to be free of marine biotoxins. The same can’t be said for blue-green algae products, like AFA, Aphanizomenon flos-aquae, a blue-green algae harvested from Klamath Lake in Oregon and marketed as a dietary supplement.

Studies have shown this blue-green algae can produce significant levels of cylindrospermopsin and saxitoxin. Cylindrospermopsin is a liver toxin and saxitoxin is a neurotoxin, listed as a Schedule 1 substance in the Chemical Weapons Convention. The first big exposé of AFA was published in 2000, with microcystin liver toxins found in 85 of 87 samples, 72 percent exceeding Oregon State’s safety limit of one part per million, which is based on an average adult weighing 60 kg (about 132 pounds) and consuming about 2 grams a day.

AFA has the toxigenic genes that produce these microcystins directly, but when you’re harvesting it outdoors, it is almost impossible to avoid the presence of other algae species that can produce toxins too. Since their release on the market and after some public inquiries about adverse health effects of these products, the producers of the Klamath Lake blue-green algae products have repeatedly claimed that their products are safe. Well…okay, maybe not safe, but at least has toxin contamination below the regulatory limit.

In 2018, dozens of blue-green algae products containing AFA were tested, and about a quarter were close to, or over, the regulatory limit, though only one Klamath lake powder significantly exceeded the limit at nearly 3 parts per million. But in 2020, two AFA supplements tested at closer to 50 parts per million. At the recommended doses, that could present up to 75 times the tolerable daily intake. When those two off-the-charts contaminated brands were tested in the 2018 survey, they only had down about the limit. This confirms that there is a potential for great variability between lots of AFA harvested from Klamath Lake. So even if a supplement company claims their brand tested under the limit, you never know what their next bottle is going to contain. Other studies have shown up to the same 50-fold variability among batches of the very same brand.

There was even a case reported of a young woman who died of liver failure tentatively attributed to the prolonged consumption of toxic AFA supplements, given the levels of the toxins the researchers were able to pick up in the liver on autopsy. In light of the findings, the distribution and commercial sale of AFA blue-green algae products for human consumption appear highly questionable. And the irony is that they are commonly consumed for purported “detoxification.”

Here’s the latest: In 2023, Klamath Lake AFA continues to be contaminated with up to ten times the upper safety limit. To minimize exposure to these toxins, the researchers suggest using spirulina or chlorella-based products instead. But are they any safer? We’ll find out next.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Doctor's Note

This is the first in a three-video series. Stay tuned for The Benefits and Dangers of Chlorella and The Benefits and Side Effects of Spirulina.

For more on DHA supplements, check out:

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