WHAT ARE AFA's?
As you can see in the graphic above, the bacteria kingdom is huge. Bacteria are wonderfully mesmerizing to me, but too vast to cover appropriately here. Some are toxic, some are not. As you may already know, I write about a certain few bacteria because many (for example the billions of strains of lactobacillus) have proven to be beneficial to human health.
The way I understand it, the cyanobacteria that is found in blue green algae is Aphanizomenon flos-aquae (AFA) which is a species of bacteria that has toxic and non-toxic forms. This bacteria uses the light from the sun, the carbon dioxide from the air and water to synthesize the lipids, proteins and carbohydrates during photosynthesis. An abundance of the world's edible supply of blue green algae products are produced by the AFA's that bloom in Klammath Lake, the largest freshwater lake in Oregon. Though Cyanobacteria is found all over the world and have been on the earth for millions, if not billions of years, it's commercial availability was initiated in the early 1980's a dietary supplement.
AFA has been shown to produce a number of health benefits during clinical research studies on mice as well as double-blind and placebo studies on humans, including but not limited to increased immunity, indications of weight loss, and reduced neuron degeneration and inflammation. Producers and users alike have stated that consuming blue green algae, spirulina and chlorella have been helpful in the treatment of many diseases from fibromyalgia to Lou Gerhig's Disease and Alzheimers to cancer. AFA's have also been shown to produce a number of negative health issues in some, including gastrointestinal discomfort, headaches, fatigue and even death in some rare cases specifically related to ingestion from a contaminated water source.
WHAT ARE THE POTENTIAL RISKS?
Over the past 20 years, humans have been in sporadically monitored without much incidence. This paper by Lorraine C. Backer explains in detail the "cyanoHAB's" (cyanobacterial harmful algal blooms), and she highlights that the majority of human illness related to cyanoHAB's recorded is due to humans being exposed to the bacteria by consuming certain shellfish and other meats, as well as ingesting or coming into skin contact with contaminated fresh water sources while enjoying recreational activities.
In 2004, a water sample collected from Klammath Lake tested positive for high concentrations of Microsystis Aerugenosa - one of the many cyanobacteria species that is a neurotoxin (harmful to the brain) and hepatoxin (harmful to the liver). This toxin is produced by the cyanobacteria when in bloom and under very specific conditions, and apparently this bloom is rare at Klammath Lake, from what I could determine, and the first incident of algal poisoning was in 1878 in Southern Australia, reported in 1997 by G. Francis.
But the greatest risk to your health is misinformation. There are plenty of positive testimonials from people who have used these supplements and experienced benefits ranging from minimal to a complete reversal of symptoms, but no one can seem to prove with empirical evidence that blue green algae, spirulina or chlorella cures anything. Science vs Nature. Proof vs Hypothesis. You can believe what you believe.