Spirulina is classified within the phylum of Cyanobacteria. Popular food and nutritional supplements, these Cyanobacterium exist as either blue-green bacteria or blue-green algae. Spirulina is a specific type of blue-green vegetable micro-algae, and is unique to only lakes which exhibit a high alkalinity. Certain African, Asian, and Mexican civilizations located within the vicinities of such lakes began to unravel spirulina’s beneficial medicinal properties thousands of years ago. Today, its worldwide popularity continues to grow as many health conscious consumers recurrently praise its extraordinary nutritional qualities.
Spirulina’s nutritional qualities are truly “one-of-a-kind.” With its structure consisting of nearly 71 percent total protein, spirulina represents the highest natural source of protein ever discovered. Its protein is fives times that of meat, and nearly three times greater than the protein of the ever-popular soybean. In addition to this astounding amino acid profile, spirulina also contains a host of other beneficial nutrients including; carotenoids, essential fatty acids, B complex vitamins, vitamin E, copper, manganese, magnesium, iron, selenium, and zinc.  In fact, spirulina’s minerals and growth factor qualities are only second to milk and evening primrose oil.
The Food and Drug Administration had indicated that spirulina is safe (GRAS), and has garnered the approval of this administration to be sold as a natural food. The World Health Organization also recognizes spirulina as a tolerable and acceptable food for human consumption. Supplemental spirulina has been used for its reputed antiviral, antioxidant, antiallergenic, hepatoprotective, hypocholesterolemic, and immune-modulatory actions. Initial results into these uses is intriguing as more research is currently being conducted to further solidify these preliminary claims.
Spirulina is available in capsule, flake, tablet, and powder form. The majority of these commercially available forms of spirulina are either cultivated from independent laboratories, or are harvested from lakes located in Mexico, California, Central and South America, and Africa. Spirulina maxima and Spirulina platensis represent the most popular forms and, as with all spirulina supplements, consists of a microscopic algae that is either dried or freeze-dried. Nutritional supplements remain the most biologically active and best source for the dietary intake of spirulina.
Recent clinical application of spirulina has suggested that the constituents, which make up this specialized blue-green algae, may provide for certain antiretroviral activities. Calcium spirulan, a sulfated polysaccharide and component of Spirulina platensis, has received the greatest attention. Studies suggest that it may offer protection against different membraned viruses.  Various in vitro studies of Spirulina platensis indicated that calcium spirulan inhibits the replication of harmful viruses, including; human cytomegalovirus, HIV-1, measles, mumps, and influenza A.  This polysaccharide may prove equally effective at minimizing the rate of replication of the herpes simplex virus (HSV-1), while also inhibiting its penetration into certain host cells. 
Spirulina may also provide for an increase of immunological activity within the body. In comparative animal study, spirulina increased natural killer (NK) cell and phagocytic activity. [5, 6] Spirulina is most effective at improving T-cell and thymus functioning. It has also been shown to increase the number of macrophages, or primary immune cells, which provide our bodies with a first line of defense. By increasing helper cells, killer cells, and antibodies, spirulina assist our immune system in the eradication of specific microbes that cause infection.
In addition to increasing immunity, spirulina may provide protection against harmful free radicals. Extracts of spirulina have been shown to scavenge peroxyl radicals in in vitro and in vivo study.  Spirulina is an algae comprised of naturally-occurring, antioxidant-rich nutrients including beta-carotenes, phenolic acids, and tocopherols. Spirulina also contains the pigment phycocyanin, which has exhibited even greater antioxidant activity in preliminary studies. Phycocyanin may also provide a mechanism of protection and treatment for persons suffering from liver damage caused by various disease conditions.  By increasing the plasma antioxidant capacities within the body, spirulina may provide some antioxidant activities.
Spirulina also harnesses the potential to reduce the incidence of any mast-cell mediated immediate-type allergic reactions by preventing the release of histamines.  Histamines are important vasoactive proteins which contribute to the various symptoms associated with an allergic reaction. Symptoms associated with the release of histamines include; runny noses, watery eyes, hives, soft-tissue swelling, and in severe cases, smooth-muscle contraction. This may prove especially relevant for individuals at risk for the onset of anaphylactic shock. 
Persons suffering from anemia, oral cancers, and elevated cholesterol, may also derive benefit from the nutritional supplementation of spirulina. [11-13] Although initial results are promising, more human research is necessary to substantiate these initial findings.
There are no established dosages for supplemental spirulina. Spirulina dosages are often dependant upon the individual manufacturer and what form is being taken. Spirulina may also be administered by the use of various synergistic combinations containing other “green foods” such as; wheat grass, barley grass, and chlorella. The most common dosages range from 250 milligrams to 5 grams, taken several times throughout the course of a given day.
The supplementation of spirulina has been deemed nontoxic in various high-dosed mammalian studies.  Animal studies have also highlighted spirulina’s safety when administered during pregnancy.  A legitimate concern, however, does exist with regard to the heavy metals that may accumulate in areas of contaminated water where spirulina is being harvested. Spirulina cultivated from areas where contamination occurs may ultimately increase the lead, mercury, and cadmium levels within the body; thereby increasing the risk factors for developing the possible toxicities associated with these agents. 
Of special interest, individuals suffering from phenylketonuria (PKU) are not advised to begin the supplemental intake of spirulina without first consulting their healthcare provider. Persons suffering from this inborn-error lack the ability to adequately metabolize the amino acid phenylalanine. As previously mentioned, spirulina is primarily comprised of protein, including the amino acid phenylalnine.
Spirulina is a nonessential nutrient, and blue-green algae is not associated with any specified deficiencies found in human physiology.
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