Initial Posting: 2/12/2016    Last Update: 8/2/2017
Answer: Concern has been raised by the fact that BMAA, a neurotoxic compound, can be produced by organisms related to Spirulina -- a common ingredient in dietary supplements, including "green" powders and drinks. Commonly referred to as a blue-green algae, Spirulina is actually a type of cyanobacteria (formerly called blue-green algae) and many cyanobacteria can produce BMAA. However, small studies suggest that dietary supplements with Spirulina are generally safe. Concerns remain, however, about other blue-green algae, particularly Aph. flos-aquae.
Another concern with supplements made from cyanobacteria is contamination with microcystin toxin — a liver toxin, which appears to be common in A. flos-aquae supplements but has also been found in some Spirulina supplements.