Spirulina is a blue-green algae. It is a simple, one-celled form of algae that thrives in warm, alkaline fresh-water bodies.

Spirulina is a rich source of protein. It also contains chlorophyll, carotenoids, minerals, gamma-linolenic acid (GLA) and some unique pigments. These pigments, called phycobilins, include phycocyanin and allophycocyanin. The pigments give spirulina their bluish tinge. Phycobilins are similar in structure to bile pigments such as bilirubin. In the spirulina cell, phycobilins are attached to proteins; the phycobilin-protein complex is called phycobiliprotein.

In addition, Spirulina is one of the few plant sources of vitamin B12, usually found only in animal tissues. A teaspoon of Spirulina supplies 21/2 times the Recommended Daily Allowance of vitamin B12 and contains over twice the amount of this vitamin found in an equivalent serving of liver.