Arthrospira

Representatives of the genus Arthrospira are free-floating filiform cyanobacteria characterized by cylindrical multicellular trichomes in a left-handed spiral. Partitions under a light microscope are indistinguishable. Mucous covers are not developed or underdeveloped.

Arthrospira platensis has an optimum pH between 8 and 11 ^[2] , found in tropical and subtropical lakes, whose water has a high pH and a concentration of carbonates and bicarbonates ^[3] . Arthrospira platensis is found in Africa, Asia and South America, while the range of Arthrospira maxima is limited to Central America. The largest commercial spirulina producers are located in the USA, Thailand, India, Taiwan, China, Bangladesh, Pakistan, Myanmar, Greece and Chile.

The growth and development of spirulina requires high temperature and light. It can survive at temperatures up to 60 ° C, and some of its desert species survive, hibernating, even if the body of water evaporates and it appears on stones with a temperature of 70 ° C . This suggests that the protein, amino acids, vitamins, enzymes contained in spirulina, even at this temperature, are stored in the cell, while under normal conditions, the temperature of 50–54 ° C for most enzymes is fatal, and some vitamins and amino acids under these conditions begin to lose their beneficial properties.

Spirulina was a food source for the Aztecs and other tribes of Mesoamerica until the XVI century, the collection of the "harvest" from Lake Texcoco and the subsequent sale of the collected algae in the form of characteristic green cakes were described by one of the soldiers of Cortes ^{[4] [5]} . The Aztecs called them tecuitlatl ^[3] . Despite the fact that, according to the results produced in the 1960s. French studies, Lake Texcoco was still rich in spirulina, there are no descriptions of the use of spirulina as a daily food source for the surrounding tribes after the 16th century. As possible factors, they call the food alternative that arose after the drainage of the neighboring lakes for larger agriculture, as well as the gradual urbanization of the region ^[3] .

Spirulina is also traditionally harvested in Chad from the many lakes and ponds surrounding Lake Chad . The algal mass is pressed into cakes called dihé , which are then used for direct consumption, and as an ingredient for cooking soups ^[6] .

Spirulina is actively cultivated, including in Russia.

Along with Lake Chad, Chinese Lake Qinghai is one of the few natural habitats of spirulina. After Lake Texcoco disappears, only naturally grown spirulina is collected in lakes Chad and Qinghai.

Protein

Dried spirulina contains about 60% (51–71%) of protein. This is a complete protein containing all the essential amino acids, albeit with a reduced content of methionine, cysteine ​​and lysine, compared with the protein of meat, eggs and milk. However, according to these indicators, spirulina is superior to other plant sources of protein, such as legumes ^{[7] [8]} .

Other Nutrients

The lipid content is about 7% by weight ^[9] , a large amount of gamma-linolenic acid ( GLA ) is present in spirulina, alpha-linolenic acid ( ALA ), linoleic acid ( LA ), stearidonic acid ( SDA ), eicosapentaenoic acid ( EPA ) are present ), docosahexaenoic acid ( DHA ) and arachidonic acid ( AA ) ^{[8] [10]} . Spirulina contains vitamins B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B6 ​​(pyridoxine), B9 (folic acid), vitamin C, vitamin D, vitamin A and vitamin E ^{[8] [10]} . Spirulina is also a source of potassium, calcium, chromium, copper, iron, magnesium, manganese, phosphorus, selenium, sodium, and zinc ^{[8] [10]} . Spirulina contains 34 times more iron than spinach and 25 times more beta-carotene than raw carrots. Spirulina contains many pigments that can be useful and bioavailable, including beta-carotene, zeaxanthin, chlorophyll a , xanthophyll, echinenone, myxoxanthophil, canthaxanthin, diatoxanthin, 3'-hydroxyecinenone, beta-cryptoxanthine and oscy phycocyanin and allophycocyanin ^[1] .

Security

Toxicology studies

Toxicological studies of the effect of spirulina intake on humans and animals, including 800 mg / kg ^[11] and replacement of up to 60% of the daily protein norm with spirulina protein ^[12] , showed no signs of toxic effects ^[13] . Fertility, teratogenicity, peri- and postnatal studies over several generations in animals also did not find any negative consequences from the use of spirulina ^[14] . As part of a study in 2009, 550 malnourished children consumed up to 10 grams of spirulina powder per day without any side effects. Numerous clinical studies have also not revealed the harmful effects of spirulina supplements ^[15] .

A 2008 study by the Institute of Hydrobiology of China found that 94% of samples (34 out of 36) of spirulina contained hepatotoxin microcystin. ^[16] In 2009, a number of studies of several dietary supplements containing cyanobacteria from various commercial suppliers for the presence of toxoid A were carried out by liquid chromatography. A total of 39 samples were analyzed in the study. The results showed that only three samples (7.7%) contained toxoid-a in concentrations from 2.50 to 33 μg (-1). ^[17]

Quality Safety Issues

Spirulina is a form of cyanobacteria, some of which secrete toxins: microcystins, BMAA and others. The presence of microcystins was detected in some spirulina samples, although their concentration was below the limit allowed by the Oregon Department of Health ^[18] . Microcystins can cause gastrointestinal upsets and, in the long run, liver cancer ^[18] , which places great demands on the choice of manufacturer of spirulina supplements. These toxic compounds are not produced by spirulina itself ^[19] , but can occur as a result of contamination of batches of spirulina with other types of blue-green algae producing toxins. Since spirulina is considered a food supplement, in many countries, in particular in the USA, there is no strict regulation of the conditions of its production and control of compliance with safety standards ^[18] . The American National Institute of Health classifies spirulina supplements as “presumably safe,” provided that they are free from microcystin contamination, and “most likely unsafe” if contaminated, especially for children. Given the lack of necessary regulations and standards, some public health researchers in the USA have expressed concern that consumers cannot be sure that there is no contamination of spirulina supplements with other blue-green algae ^[18] . The frequent contamination of spirulina supplements with heavy metals is also of concern. The State Food and Drug Administration of China reported that contaminants of lead, mercury and arsenic are often found in spirulina supplements sold in China ^[20] .

Security for specific groups

Due to the very high content of vitamin K in spirulina, patients undergoing anticoagulant treatment should consult a doctor before using the supplement to adjust the required dose of the medicine. Like all protein-rich foods, spirulina contains a significant amount of the phenylalanine amino acid (2.6-4.1 g / 100 grams of product) ^[3] , which should be avoided by people with phenylketonuria ^[21] .

In vitro research

The main active component of spirulina is Phycocyanobilin, which makes up about 1% of the mass of spirulina ^{[22] [23]} . This compound slows down the reactions of NADPH oxidase ^[24] . Spirulina has been studied in vitro as an anti-HIV agent ^[25] , as an iron chelating agent ^[26] , and as a radioprotective agent ^[27] . Animal studies evaluated the effects of spirulina in preventing chemotherapy-induced damage to the heart ^[28] , recovery from stroke ^[29] , age-related memory impairment ^[30] , diabetes ^[31] , amyatrophic lateral sclerosis ^[32] , hay fever ^{[33] ]} .

Pseudovitamin B12

Vitamin B12 is especially needed for vegans and vegetarians. The body receives most of Vitamin B12 from animal foods, while vegans and vegetarians lacked it, receiving vitamin C from small doses. Studies conducted in 2014 showed that spirulina contains components similar to the necessary vitamin, they are called "pseudovitamin B12". However, the effects of spirulina on blood vitamin B12 have not been clinically proven. For 2015, the question of vitamin B12 in spirulina, however confirmed, has not been refuted by any study.

Human Research

Some studies have been conducted to evaluate the effects of spirulina on the body of malnourished children ^[34] , as a treatment for the cosmetic aspects of arsenic poisoning ^[35] , hay fever and allergic rhinitis ^{[36] [37]} , arthritis ^[38] , and hyperlipidemia and hypertension ^{[38] [39]} as a means of increasing physical endurance ^[40] . The presence of β-carotene antioxidant in spirulina suggests the presence of some antitumor activity. There is some evidence of a positive effect of spirulina on lowering blood cholesterol , but before making final conclusions about its effectiveness, a large amount of additional research is required. Separate experiments have shown the promise of further studies of the effectiveness of spirulina in chronic fatigue syndrome and as an antiviral agent.

In the late 1980s and early 90s, both NASA (CELSS) ^[41] and the European Space Agency ^[42] proposed spirulina as one of the main cultivation products during long space missions.

• Chlorella

• Arthrospira in the cyanobacteria database on Cyanodb.cz
• Karkos PD, Leong SC, Karkos CD, Sivaji N. and Assimakopoulos DA Spirulina in Clinical Practice: Evidence-Based Human Applications (EN) // Evid Based Complement Alternat Med: Published online. - 2010 .-- T. v . 2011 . - DOI : 10.1093 / ecam / nen058 . - PMID PMC3136577.
• Blue-green Algae (neopr.) . MedlinePlus . National Institutes of Health (December 2011). Archived January 5, 2013.
• Spirulina Benefit and Harm