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.
Spirulina is a microscopic blue-green algae whose carotenoid pigments are responsible for the orange-pink hue of flamingos. At high-enough doses, it can also turn us orange too––like if we eat too many carrots. But it’s considered benign, and goes away on its own when you cut back. The strangest color change I ran across was this: “Green Breast Milk Following Ingestion of Blue-Green Algae.” Whoa! But thankfully, that also disappears after stopping.
Spirulina is said to have various promising health effects. At the same time, on the contrasting note, there are toxins that might contribute to acute poisoning, cancer, liver damage, and gastrointestinal disturbances, with long-term consumption potentially leading to Alzheimer’s and Parkinson’s disease. Okay, then. And those purported promised health effects, like playing “a positive role in treating muscle cramps,” are based on a study in which mice were injected with formaldehyde and vinegar.
What can spirulina actually do in people? Spirulina can improve long-term blood sugar control in rats, but, apparently, not in humans. It’s also disappointing when it comes to anti-inflammatory or antioxidant effects. Spirulina may help lower cholesterol, though, perhaps due to reducing fat absorption, and lower blood pressures by four or five points. There was a recent trial where mild-to-moderate Alzheimer’s patients were randomized to a gram a day of spirulina or placebo for 12 weeks, and appeared to end up slightly better off cognitively than those in the control group. So those are some of the potential upsides. The concern is that, although algae supplements like blue-green algae, chlorella, and spirulina are all advertised as being beneficial, they might be harmful because they may contain algal toxins.
Though most toxins are found contaminating the Klamath lake AFA blue-green algae, some toxins are found in some spirulina supplements as well. Spirulina samples tested from markets around the world have shown highly variable results, ranging from non-detection to alarming levels of toxins. The presence of toxin-producing algae contaminants is the most likely explanation for the presence of toxins in spirulina products, because producers cultivate spirulina in open outdoor ponds, which are vulnerable to contamination with toxin-producing species.
There have been calls for strict quality control and monitoring, but that doesn’t seem to have panned out. This study examined what was growing in five commercial spirulina products, including pills and powders. Several potentially pathogenic bacteria were detected in the products, and algae toxins were found in all of the products at levels that could lead to consumers exceeding the recommended daily limits. One study of five protein powders with spirulina found that four of them even contained BMAA, which is a neurotoxin linked to some progressive neurodegenerative diseases like ALS, which I’ve talked about before.
Yet spirulina products continue to be advertised as detoxifiers. Though spirulina is commonly contaminated, the level of toxins is significantly lower than has been found in other blue-green algae supplements. Nevertheless, there’s a concern that long-term exposure to even very low levels of these toxins may increase the risk of liver cancer, for example. There are also case reports of acute liver damage tentatively tied to spirulina intake, as well as acute muscle damage and rare autoimmune reactions to spirulina, AFA blue-green algae, or both, including blistering disorders too disturbing to display.
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