Spirulina (Blue-green alga) is a microscopic and filamentous cyanobacterium that derives its name from the spiral or helical nature of its filaments. Spirulina became famous after it was successfully used by NASA as a dietary supplement for astronauts on space missions because of the high (up to 70%) content of protein, and it also contains vitamins, especially B12 and provitamin A (β-carotenes), and minerals, especially iron. It is also rich in phenolic acids, tocopherols and γ-linolenic acid. Spirulina lacks cellulose cell walls and therefore it can be easily digested. The highly nutritional Spirulina has hypolipidemic, hypoglycemic, and antihypertensive properties. Spirulina contains functional compounds, such as phenolics, phycocyanins, and polysaccharides, with antioxidant, anti-inflammatory, and immunostimulating effects. Spirulina now belongs to the substances that are listed by the US Food and Drug Administration under the category Generally Recognized as Safe (GRAS).