Spirulina is a cyanobacterium (blue-green algae) that can be consumed by humans and other animals. There are two species, Arthrospira platensis and Arthrospira maxima. Arthrospira is cultivated worldwide; used as a dietary supplement as well as a whole food; and is also available in tablet, flake and powder form. It is also used as a feed supplement in the aquaculture, aquarium and poultry industries.
Dried spirulina contains about 60% (51–71%) protein. It is a complete protein containing all essential amino acids, with slightly lower amounts of methionine, cysteine, and lysine compared to certain animal-derived products. From a nutritional point of view, spirulina is no better than other protein sources, but is more expensive gram-for-gram and may have adverse interactions when taken with prescribed drugs. Provided in its typical supplement form as a dried powder having 5% water, a 100 gram amount of spirulina supplies 290 Calories and is an excellent source (20% or more of the Daily Value, DV) of numerous nutrients, particularly B vitamins (thiamin and riboflavin, 207% and 306% DV, respectively) and dietary minerals, such as iron (219% DV) and manganese (90% DV).
Spirulina’s lipid content is 8% by weight providing gamma-linolenic acid, alpha-linolenic acid, linoleic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and arachidonic acid.
Because spirulina is considered a dietary supplement in the U.S., no active, industry-wide regulation of its production occurs and no enforced safety standards exist for its production or purity.