# Spirulina Supplements as a Source of Mineral Nutrients in the Daily Diet
## 1 Introduction  
Spirulina (_ArtInrospira_ sp.) is a microalga that has been consumed for centuries by indigenous peoples in Mexico and northern Africa [1]. The alkaline lakes which can be found in those regions are its natural habitat [2]. Spirulina belongs to the phylum cyanobacteria, and the term covers two species of microalgae--_Arthrospira platensis_ and _ArthInospira maxima_. Both are used in the production of food and dietary supplements [3, 4]. Spirulina is capable of oxygenic photosynthesis and reproduces asexually by binary fission until itreaches its mature status [5]. Spirulina is currently the most popular commercially grown algae. The main producers are the DIC group of companies, Earthrise in California (USA) and Hainan DIC Marketing on Hainan Island (China), as well as Cyanotech Corporation of Hawaii. Smaller producers are located primarily in the Asia-Pacific region (mainly in China and India) [6], although there are plans to grow this alga in Europe as well [7]. Briefly, the harvesting of spirulina occurs from natural habitats that are difficult to control in view of the chemical composition of the environment, and from environments where the environmental parameters (temperature, pH, light, chemical composition of the culture medium, among others) are under human control [6; 8]. The protein content of _Arthospira_ can be as high as 70%, and it is protein of high biological value, due to its content of all essential amino acids in the proportions recommended by the FAO (Food and Agriculture Organization). Consequently, it is superior to other plant sources of protein and as valuable as eggs, meat and milk [9]. Of particular note is the content of polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [10]. It is also important to mention the vitamin content--A, D, E, K and group B vitamins. The high content of vitamin B12 makes spirulina particularly valuable for vegans and vegetarians who, due to the lack of meat products in their diet, may be at risk of deficiencies of this vitamin [11]. Spirulina is a good source of mineral nutrients such as Ca, Fe, Se, F or I [12; 13; 14; 15]. It also contains high amounts of carotenoids (astaxanthin, zeaxanthin, \(\beta\)-carotene), polyphenols and chlorophyll [10; 11; 16]. With such a plethora of bioactive compounds, _Arthospira_ boasts antioxidant, anti-inflammatory and immunomodulatory properties [17]. It has also been found to inhibit the activity of viruses, including HIV and influenza virus [18]. The antioxidant effects of spirulina can be attributed to its ability to regulate antioxidant enzymes, such as superoxide dismutase, catalase and glutathione peroxidase. Spirulina also inhibits cyclooxygenase-2, as well as inducible nitric oxide synthase gene expression. Findings from animal studies suggest its protective effect against the harmful effects of heavy metals [17]. Spirulina has been shown to effectively lower triacylglycerlecrols and LDL cholesterol in the blood and to help lower blood pressure [19]. In addition, it has been reported to have a blood-glucose-lowering effect in diabetes patients [16]. Its effects also include aiding weight loss in obese people and improving metabolic parameters, e.g., increasing insulin sensitivity, reducing inflammation, lowering total and LDL cholesterol and increasing HDL cholesterol [20]. Preliminary clinical studies have suggested that spirulina may exert neuroprotective effects, particularly in malnourished children, by supporting brain development and improving language and motor skills. In addition, it can be beneficial in alleviating mental and physical fatigue [21]. In in vitro research, it has been demonstrated that spirulina has a positive effect on the abundance of the human microbiota, which means that it could be used as a prebiotic [22]. Despite numerous studies conducted in vitro and in animal models, the effects of spirulina on the human body have not been fully investigated and confirmed.