This came up on a c60 thread where it was off topic. I expressed my concern with blue-green "algae" supplements, which are not algae at all but photosynthesizing bacteria often grown in sewer- and agricultural runoff-rich waters. In fact, cianobacterial bloom is the sure sign of seriously poor water quality, often endangering aquatic animals and plants.
In the US, one source of blue-green "algae" is Klamath lake. Here is what wiki says about it:
http://en.wikipedia....er_Klamath_Lake
The lake is naturally eutrophic, resulting in a high concentration of nutrients. In the 20th century, the augmentation of nutrients by agricultural runoff from the surrounding farming valley has caused the lake to become hypereutrophic, resulting in blue-green algae blooms over the lake ( largely Microcystis aeruginosa and Aphanizomenon flos-aquae). The algae blooms turn the water an opaque green in the summer and reduce the opportunity for recreational uses of the lake. State standards for dissolved oxygen are routinely violated, meaning that fish are endangered.
Turnbuckle's reply seemed perfectly reasonable at a first glance:
See, it is the nutrients from agricultural runoff that cause the cianobacterial blooms in Klamath lake. If you care to study this subject, it has always been either animal or human waste that supported cianobacterial growth.
And the plants you are eat grow in dirt with all those same things in it. So what?
Ah! But the situation with cianobacteria is very different from plants. Harvesting bacteria, you cannot separate them from the "nutrient-rich medium" (yeah, shit) in which they grow. Nor can you ensure that your harvest is free from other microorganisms naturally found in agricultural runoff, which includes many pathogenic and antibiotic-resistant strains.
Using turnbuckle's analogy, we don't harvest plants, dirt and all, together with weeds, including poisonous ones. And cianobacteria are not plants. Calling them "algae" is a marketing tool.
In the US, there are many inexpensive blue-green "algae" suppliers who compete with expensive Japanese brands of spirulina (grown in special ponds), whose high price reflects the difficulty in assuring both effectiveness and safety of a properly produced product.
http://en.wikipedia....tary_supplement)
Spirulina is a form of cyanobacterium, some of which are known to produce toxins such as microcystins, BMAA, and others. Some spirulina supplements have been found to be contaminated with microcystins, albeit at levels below the limit set by the Oregon Health Department. Microcystins can cause gastrointestinal disturbances and, in the long term, liver cancer. The effects of chronic exposure to even very low levels of microcystins are of concern, because of the potential risk of cancer.
These toxic compounds are not produced by spirulina itself, but may occur as a result of contamination of spirulina batches with other, toxin-producing, blue-green algae. Because spirulina is considered a dietary supplement in the U.S., there is no active, industry-wide regulation of its production and no enforced safety standards for its production or purity. The U.S. National Institutes of Health describes spirulina supplements as "possibly safe", provided they are free of microcystin contamination, but "likely unsafe" (especially for children) if contaminated. Given the lack of regulatory standards in the U.S., some public-health researchers have raised the concern that consumers cannot be certain that spirulina and other blue-green algae supplements are free of contamination.
In summary, blue-green "algae" supplements produced in the States (or in China) cannot be considered safe. IMO, the worse contaminants they may contain are antibiotic-resistant pathogens found in agricultural runoff, which constitutes their natural growth medium.
