Spirulina is a biomass of cyanobacteria (blue-green algae) that can be consumed by humans and animals. The three species are Arthrospira platensis, A. fusiformis, 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.
Etymology and ecology
The species A. maxima and A. platensis were once classified in the genus Spirulina. The common name, spirulina, refers to the dried biomass of A. platensis, which belongs to photosynthetic bacteria that cover the groups Cyanobacteria and Prochlorophyta. Scientifically, a distinction exists between spirulina and the genus Arthrospira. Species of Arthrospira have been isolated from alkaline brackish and saline waters in tropical and subtropical regions. Among the various species included in the genus Arthrospira, A. platensis is the most widely distributed and is mainly found in Africa, but also in Asia. A. maxima is believed to be found in California and Mexico. The term spirulina remains in use for historical reasons.
Arthrospira species are free-floating, filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-handed helix. They occur naturally in tropical and subtropical lakes with high pH and high concentrations of carbonate and bicarbonate. A. platensis occurs in Africa, Asia, and South America, whereas A. maxima is confined to Central America. Most cultivated spirulina is produced in open-channel raceway ponds, with paddle wheels used to agitate the water.
Spirulina thrives at a pH around 8.5 and above and a temperature around . They are autotrophic, meaning that they are able to make their own food, and do not need a living energy or organic carbon source. A nutrient feed for growing it is:
Baking soda
Potassium nitrate
Sea salt-
Potassium phosphate
Iron sulphate
Historical use
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 by the Aztecs as a daily food source was made after the 16th century, probably because of the draining of the surrounding lakes for agriculture and urban development. The topic of tecuitlatl, which was discovered in 1520, was not mentioned again until 1940, when the Belgian phycologist Pierre Dangeard mentioned a cake called dihe consumed by the Kanembu tribe, who harvest it from Lake Chad in the African nation of Chad. Dangeard studied the dihe samples and found it to be a dried puree of the spring form of the blue-green algae from the lake. The dihe 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.
Food and nutrition
Spirulina is being investigated to address food security and malnutrition, and as dietary support in long-term space flight or Mars missions. Its advantage for food security is that it needs less land and water than livestock to produce protein and energy.
Dried spirulina contains 5% water, 24% carbohydrates, 8% fat, and about 60% (51–71%) protein.
As seen in the table of nutritional value, provided in its typical supplement form as a dried powder, a 100-g amount of spirulina supplies and is a rich source (20% or more of the Daily Value, DV) of numerous essential nutrients, particularly protein, B vitamins (thiamin, riboflavin, and niacin, providing 207%, 306%, and 85% DV, respectively), and dietary minerals, such as iron (219% DV) and manganese (90% DV). The lipid content of spirulina is 8% by weight providing the fatty acids, gamma-linolenic acid, linoleic acid, stearidonic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid. In contrast to those 2003 estimates (of DHA and EPA each at 2 to 3% of total fatty acids), 2015 research indicated that spirulina products "contained no detectable omega-3 fatty acids" (less than 0.1%, including DHA and EPA).