Any cyanobacteria in the genus Spirulina .
A traditional food source in parts of Africa and Mexico, spirulina is an exceptionally rich source of vitamins, minerals, and protein, and one of the few nonanimal sources of vitamin B 12 . It is now being widely studied for its possible antiviral, anticancer, antibacterial, and antiparasitic properties, and has been used for such medical conditions as allergies, ulcers, anemia, heavy-metal poisoning, and radiation poisoning. It is also used in weight-loss programs.