Spirulina represents a biomass of cyanobacteria (blue-green algae) that can be consumed by humans and other animals. The two species are Arthrospira platensis and A. maxima.

Cultivated worldwide, Arthrospira is used as a dietary supplement or whole food. It is also used as a feed supplement in the aquaculture, aquarium, and poultry industries.

Spirulina was a food source for the Aztecs and other Mesoamericans until the 16th century; the harvest from Lake Texcoco in Mexico and subsequent sale as cakes were described by one of Cortés’ soldiers. The Aztecs called it “tecuitlatl”.

Spirulina was found in abundance at Lake Texcoco by French researchers in the 1960s, but no reference to its use was made by the Aztecs as a daily food source after the 16th century, probably due to the draining of the surrounding lakes for agriculture and urban development. The topic of the Tecuitlalt, which was earlier discovered in 1520, was not mentioned again until 1940, the French phycologist Pierre Dangeard mentioned about a cake called “dihe”, consumed by Kanembu tribe, African Lake Chad, Kanem (Chad, Africa). Dangeard studied the “dihe” samples and found that it is like a puree of spring form blue algae. Spirulina has also been traditionally harvested in Chad. It is dried into dihé, which is used to make broths for meals, and also sold in markets. The spirulina is harvested from small lakes and ponds around Lake Chad.

During 1964 and 1965, the botanist Jean Leonard confirmed that dihe is made up of spirulina, and later studied a bloom of algae in a sodium hydroxide production facility. As a result, the first systematic and detailed study of the growth requirements and physiology of spirulina was performed as a basis for establishing large-scale production in the 1970s.

As an ecologically sound, nutrient-rich, dietary supplement, spirulina is being investigated to address food security and malnutrition, and as dietary support in long-term space flight or Mars missions. Its interest for food security is for lower land and water needs to produce protein and energy than required for livestock as meat sources.

Dried spirulina contains 5% water, 24% carbohydrates, 8% fat, and about 60% (51–71%) protein.