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Spirulina (dietary supplement)

Spirulina is the common name for human and animal food supplements produced primarily from two species of cyanobacteria (also known as blue-green algae): Arthrospira platensis, and Arthrospira maxima. These and other Arthrospira species were once classified in the genus Spirulina. There is now agreement that they are distinct genera, and that the food species belong to Arthrospira; nonetheless, the older term Spirulina remains the popular name. Spirulina is cultivated around the world, and is used as a human dietary supplement as well as a whole food and is available in tablet, flake, and powder form. It is also used as a feed supplement in the aquaculture, aquarium, and poultry industries.

Biology

Spirulina are free-floating filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-hand helix. Spirulina occurs 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.

History

Spirulina is believed to have been a food source for the Aztecs and other Mesoamericans until the 16th-century; its harvesting from Lake Texcoco and subsequent sale as cakes is described by one of Cortés' soldiers. The Aztecs called it Tecuitlatl, meaning stone's excrement. Spirulina was found in abundance at the lake by French researchers in the 1960s, but there is no reference to its use there as a daily food source after the 16th century. The first large-scale Spirulina production plant, run by Sosa Texcoco, was established there in the early 1970s.

Leo Szilard postulated the development of algae-based food supplements (which he called "Amruss") in his 1961 short story, The Voice of the Dolphins.

Spirulina may have an even longer history in Chad, as far back as the 9th century Kanem Empire. It is still in daily use today, dried into cakes called Dihé, which are used to make broths for meals, and also sold in markets. The Spirulina is harvested from small lakes and ponds around Lake Chad.

Cultivation

Most cultivated spirulina is produced in open-channel raceway ponds, with paddle-wheels used to agitate the water. The largest commercial producers of spirulina are located in the United States, Thailand, India, Taiwan, China, Pakistan and Myanmar (i.e. Burma).

Nutrients and other chemicals

Protein

Spirulina contains an unusually high amount of protein, between 55% and 77% by dry weight, depending upon the source. It is a complete protein, containing all essential amino acids, though with reduced amounts of methionine, cysteine, and lysine when compared to the proteins of meat, eggs, and milk. It is, however, superior to typical plant protein, such as that from legumes.

Essential fatty acids

Spirulina is rich in gamma-linolenic acid (GLA), and also provides alpha-linolenic acid (ALA), linoleic acid (LA), stearidonic acid (SDA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA).

Vitamins

Spirulina contains vitamin B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B6 (pyridoxine), B9 (folic acid), vitamin C, vitamin D, and vitamin E. The bioavailability of vitamin B12 in Spirulina is in dispute. Several biological assays have been used to test for the presence of vitamin B12. The most popular is the US Pharmacopeia method using the Lactobacillus leichmannii assay. Studies using this method have shown Spirulina to be a minimal source of bioavailable vitamin B12. However, this assay does not differentiate between true B12 (cobalamin) and similar compounds (corrinoids) that cannot be used in human metabolism. Cyanotech, a grower of spirulina, claims to have done a more recent assay, which has shown Spirulina to be a significant source of cobalamin. However the assay is not published for scientific review and so the existence of this assay is in doubt. The American Dietetic Association and Dietitians of Canada in their position paper on vegetarian diets state that spirulina can not be counted on as a reliable source of active vitamin B12.

Tests done on Australian grown spirulina by the Australian Government Analytical Laboratory (AGAL) show Vitamin B12 (cobalamin) levels of 659.1ug / per100g . A one gram tablet could provide more than three times the recommended daily intake of B12.

Minerals

Spirulina is a rich source of potassium, and also contains calcium, chromium, copper, iron, magnesium, manganese, phosphorus, selenium, sodium, and zinc.

Photosynthetic pigments

Spirulina contains many pigments including chlorophyll-a, xanthophyll, beta-carotene, echinenone, myxoxanthophyll, zeaxanthin, canthaxanthin, diatoxanthin, 3'-hydroxyechinenone, beta-cryptoxanthin, oscillaxanthin, plus the phycobiliproteins c-phycocyanin and allophycocyanin.

Evidence of health and healing effects

Despite existing research supporting Spirulina's health and healing properties, detractors claim that these are frequently overstated by Spirulina advocates. Conversely, Spirulina advocates have accused health food detractors of dismissing all such claims without acknowledging this research. Two online publications exemplify these opposing positions, respectively: Wellness Letter on Blue Green Algae, and Superfoods For Optimum Health: Chlorella and Spirulina Many positive claims are based on research done on individual nutrients that Spirulina contains, such as GLA, various antioxidants, etc., rather than on direct research using Spirulina. What follows is research on the health and healing effects of Spirulina. In vitro research (e.g., studying cells in a petri dish) may suggest the possibility of similar results in humans but, due to the drastically different conditions of the research, provides only hints at the potential for human effects. Animal research can also provide evidence of potential human effects. Human research focuses on actual effects in humans - however, the validity and reliability of the research depends on the design of the study. The strongest evidence comes from well designed and controlled clinical trials, which are one type of human research study.

In vitro research

Spirulina extract inhibits HIV replication in human T-cells, peripheral blood mononuclear cells (PBMC), and Langerhans cells.

Animal research

Spirulina helps prevent heart damage caused by chemotherapy using Doxorubicin, without interfering with its anti-tumor activity. Spirulina reduces the severity of strokes and improves recovery of movement after a stroke; reverses age-related declines in memory and learning; and prevents and treats hay fever.

Human Research

Spirulina is effective for the clinical improvement of melanosis and keratosis due to chronic arsenic poisoning; improves weight-gain and corrects anemia in both HIV-infected and HIV-negative undernourished children; and protects against hay fever.

A 2007 study found that 36 volunteers taking 4.5 grams of spirulina per day, over a six week period, exhibited significant changes in cholesterol and blood pressure: (1) lowered total cholesterol; (2) increased HDL cholesterol; (3) lowered triglycerides; and (4) lowered systolic and diastolic blood pressure. However, as this study did not contain a control group, researchers can not be confident that the changes observed are due totally - or even partially - to the effects of the Spirulina Maxima as opposed to other confounding variables (i.e., history effects, maturation effects, demand characteristics).

Advocates

The United Nations World Food Cenference in 1974 lauded Spirulina as the 'best food for the future'. Recognising the inherent potential of Spirulina in the sustainable development agenda, several Member States of the United Nations came together to form an intergovernmental organization by the name of the Intergovernmental Institution for the Use of Micro-algae Spirulina Against Malnutrition. IIMSAM aspires to build a consensus to make Spirulina a key driver to eradicate malnutrition, achieve food security and bridge the health divide throughout the world.

Spirulina has been proposed by both NASA (CELSS) and the European Space Agency (MELISSA) as one of the primary foods to be cultivated during long-term space missions.