The Blue-Green Algae Debate

By Robert Rountree, MD

I’ve been taking algae supplements for years, but I heard recently that they might be toxic. Are they? For many years, I too have heard concerns about the potential toxicity of blue-green algae, but I suspect the research you mention stems from a recent scientific study of the indigenous Chamorro people from the Pacific island of Guam. An unusually high percentage of that population has long been afflicted with a devastating progressive neurodegenerative illness that has features similar to ALS (Lou Gehrig’s disease), Parkinson’s, and Alzheimer’s.

Scientists thought the culprit might be some kind of slow-acting poison from the seeds of the cycad plant, which is an ingredient in the tortillas that are a dietary staple in that region. The new study found that a blue-green algae that lives symbiotically in the roots of the cycad plant produces a neurotoxic amino acid called BMAA, which was highly concentrated in the brain tissues of people who had succumbed to the disease.

At first, researchers thought the problem was confined to Guam, but this same toxin was then identified in the brains of people with Alzheimer’s disease who lived in Canada and did not eat cycads. This led the researchers to speculate that BMAA and other neurotoxins from blue-green algae commonly found in drinking water could play a role in the current worldwide epidemic of Alzheimer’s and other neurodegenerative diseases. Not surprisingly, the media immediately picked up this hypothesis and warned the public of the potential dangers of taking algae supplements.

But before you get all worked up and start tossing your spirulina powder, consider these basic facts of biology. First of all, there are many different types of algae, including blue-green, green, brown, and red varieties. They can range in size from microscopic single-celled organisms to bull kelp, which is hundreds of feet in length. The biological properties of all these different algae vary as much as their size and color. Consequently, just because one strain can produce a toxin does not mean this is true of all algae. This should be reassuring to the millions of people who regularly enjoy eating kelp, wakame, hijiki, nori, and other seaweed, since these foods have never been found to contain toxins.

The biggest source of concern is wild strains of blue-green algae that thrive in the nutrient-rich—and often polluted—waters of lakes, ponds, and streams. It is well known that these types of algae have a tendency to produce liver toxins called microcystins. The only type of blue-green algae that does not have this tendency is spirulina, which is cultivated under highly controlled conditions that guarantee the absence of toxins. Similarly, chlorella, a cultivated microscopic green algae, is also known to be free of toxins so, like spirulina, it is quite safe to take as a dietary supplement.

Just make sure you investigate your supplement. Any company that sells wild blue-green algae as a dietary supplement should be able to prove that they have employed the strictest level of quality control to ensure that their product is BMAA or microcystins-free.

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