Spirulina (genus Arthrospira) belongs to the family of cyanobacteria and was once classified as the “blue-green algae’’. It is commonly called a “microalgae” and is marketed as a dietary supplement. Arthrospira are free-floating, filamentous cyanobacteria that average 0.15 mm in length. Spirulina is cultivated worldwide in factories or in open waters, where it is collected and dried using convective hot air (usually around 135 °C). It is then processed into powder or tablets.
Some forms of cyanobacterium are known to produce toxins such as microcystins. Some spirulina supplements have been found to be contaminated with microcystins, albeit at levels below the limit set by the Oregon Health Department. Microcystins can cause gastrointestinal disturbances, and in the long term, liver damage. Spirulina does not produce these toxic compounds, but they may occur because of contamination of spirulina batches with other toxin-producing blue-green algae. This is in direct contrast to the detoxifying effect spirulina is said to have.
Heavy-metal contamination of spirulina supplements has also raised concern. The Chinese State Food and Drug Administration reported that lead, mercury, and arsenic contamination was widespread in spirulina supplements marketed in China. One study reported the presence of lead at levels of up to 5.1 ppm in a sample from a commercial supplement.
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. The U.S. National Institutes of Health describes spirulina supplements as "possibly safe," provided they are free of microcystin contamination, but "likely unsafe" (especially for children) if contaminated. Given the lack of regulatory standards in the U.S., some public-health researchers have raised the concern that consumers cannot be certain that spirulina and other blue-green algae supplements are free of contamination.
Spirulina doses of 10 to 19 grams per day over several months have been used safely. Adverse effects may include nausea, diarrhea, fatigue, or headaches.1
Spirulina has a protein content of 60 % - which is not exactly beneficial for our western eating habits which are already too high in protein!
Approximately 3,000 tons of commercially produced raw spirulina mass is sold annually as a nutritional supplement in powdered and tablet form. It is added to organic foods like noodles, fruit bars, and powdered drink mixes as a nutrient-rich ingredient.
Spirulina thrives at an alkaline pH around 8.5 and above, and at temperatures from 30 °C (86 °F) – 37 °C (99 °F). It occurs naturally in warm waters around the world, including Africa, Asia, South America, and Australia. Researchers have isolated Arthrospira from alkaline brackish and saline waters in tropical and subtropical regions. Most cultivated spirulina is produced in open-channel raceway ponds, with paddle wheels used to agitate the water. Agitation of algal cultures has the advantage of uniform distribution of CO2 aeration, which is essential in getting good quality and better yields of Spirulina.
During harvest, the spirulina is pumped through a filter or a continuous centrifuge. The resulting thick mass is then dried in a drying chamber using hot air or outdoors in the sunlight. The producers then press the dry powder into tablets, enclose it in capsules, or pulverize it for retail.1, 2
You can purchase spirulina supplements in health food stores, grocery stores, and online. Be careful to buy certified organic spirulina to ensure that it is not contaminated.
Dried spirulina contains 5% water, 24% carbohydrates, 8% fat, and about 60% (51–71%) protein. Various claims are made about the nutritional benefits of spirulina, especially about vitamin B12. Research proves that spirulina does not contain vitamin B12 naturally, and spirulina supplements contain predominantly pseudovitamin B12 which is biologically inactive in humans. In a 2009 position paper on vegetarian diets, the American Dietetic Association stated that spirulina is not a reliable source of active vitamin B12. The medical literature similarly advises that spirulina is unsuitable as a source of B12.3
Administration of spirulina has been investigated as a way to control glucose in people with diabetes, but the European Food Safety Authority rejected those claims in 2013.1
Holistic medicine practitioners claim that spirulina intake helps battle cancer, viruses, and allergies. While it is theorized that spirulina intake may have the effect of reducing serum cholesterol levels, the studies which were completed showed only minor effects. The sample sizes in the studies were too low, and the studies were poorly designed, so no reliable results have been achieved to date. ... The immunomodulating effect of spirulina in other areas, including allergic reactions where spirulina acts as a mast cell inhibitor, has been studied – spirulina blocks the release of histamines from mast cells.2
Spirulina has been studied as a potential nutritional supplement for adults and children affected by HIV, but there was no conclusive effect on risk of death, body weight, or immune response.
According to the U.S. National Institutes of Health, scientific evidence is insufficient to recommend spirulina supplementation, and more research is needed to clarify whether consumption yields any benefits.
Spirulina may cause adverse interactions when taken with prescription drugs, particularly those affecting the immune system and blood clotting.
Like all protein-rich foods, spirulina contains the essential amino acid phenylalanine (2.6-4.1 g/100 g), which should be avoided by people who have phenylketonuria. This is a rare genetic disorder that prevents the body from metabolizing phenylalanine, which then builds up in the brain, causing damage.1
Wikipedia: 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.1
In 1940, the French phycologist Pierre Dangeard mentioned a cake called “dihé,” consumed by the Kanembu tribe, African Lake Chad, Kanem (Chad, Africa). Dangeard studied the “dihé” samples and found that they were made from a puree of blue algae, or spirulina. Harvesting spirulina is a tradition in Chad. It is dried into dihé, which is used to make broths for meals, and sold in markets. The spirulina is harvested from small lakes and ponds around Lake Chad.1
One feature unique to cyanobacteria is that they use the energy of sunlight to drive photosynthesis, a process where the energy of light is used to synthesize organic compounds from carbon dioxide. Some classes of cyanobacteria produce phycocyanin which is blue-green. These bacteria were referred to as “blue-green algae” in the past.4