Spirulina is the common name for human and animal food supplements produced primarily from two species of cyanobacteria: 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 inaccurate term "Spirulina" remains the popular name. Spirulina is cultivated around the world, and is used as a human dietary supplement, available in tablet, flake, and powder form. It is also used as a feed supplement in the aquaculture and poultry industries. Spirulina contains unusually high amounts 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, as compared to standard proteins such as that from meat, eggs, or milk; it is, however, superior to all standard plant protein, such as that from legumes.  Essential Fatty Acids Spirulina tabletsSpirulina is rich in gamma-linolenic acid (GLA). However, one needs to use 5-10 grams of dried spirulina to obtain similar quantities as that found in 1000 mg evening primrose oil or 500 mg borage oil. Spirulina also provides small quantities of other fatty acids such as alpha-linolenic acid (ALA), linoleic acid (LA), stearidonic acid (SDA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA).  Vitamins Spirulina contains most vitamins in high quantities, but are richest in vitamin A (in the form of beta-carotene), vitamin D, vitamin K, vitamin B1, vitamin B2 and vitamin B12.  The bioavailability of vitamin B12 in Spirulina is in dispute. Several biological assays have been used to verify 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 actually differentiate between human bioavailable and non-human bioavailable B12. A more recently developed assay performed by a grower of spirulina has shown Spirulina to be a significant source of bioavailable B12.  Minerals Dried spirulina has a very high concentration of mineral ash. It is a very rich source of iron, and also contains many other minerals such as manganese, chromium, selenium, magnesium, calcium and phosphorus. Some spirulina brands add zinc during the cultivation period, so that the supplement ends up very rich in this mineral. It should be noted, that even though spirulina is rich in many minerals, the dosages used for supplementation - 0.5-10 grams daily - provides relatively little of most of those minerals compared to the RDAs. Using more than 10 grams of dried spirulina could in time lead to iron and vitamin D toxicity. 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. Source:http://en.wikipedia.org/wiki/Spirulina A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material. In particular, powders refer to those granular materials that have the finer grain sizes, and that therefore have a greater tendency to form clumps when flowing. Granulars refers to the coarser granular materials that do not tend to form clumps except when wet.