Chlorella is a green alga that appeared on Earth more than 2 billion years ago. Formed of a single cell, spherical, it owes its color to the chlorophyll (pigment of photosynthesis) that it contains in exceptional quantity.
Discovered in 1890 by a Dutch microbiologist Martinus Willem Beijerinck, the chlorella species has been divided into three varieties since 2004: chlorella vulgaris, chlorella lobophora and chlorella sorokiniana. Chlorella vulgaris is currently the most cultivated because it is the most suitable for algae farms.
Historically, chlorella was first produced and consumed in Asia, mainly in Japan, then very quickly, the island of Formosa (present-day Taiwan) became the world's leading producer.
Moreover, since 1950, numerous researches have been carried out when chlorella was thought to be a useful food to counter the possible world food shortage linked to the increase of the population. Unfortunately, chlorella is difficult to digest in its natural state and has not been retained as a viable solution. Indeed, its wall is made of cellulose that needs to be broken before being consumed.
Its therapeutic capacities are proven. In Japan, it is even considered as a food of national interest for health and in 1957, the institute for research on chlorella is created.
[ 1] Krienitz L. & al.: Phylogenetic relationship of Chlorella and Parachlorella gen. nov. (Chlorophyta, Trebouxiophyceae). Phycologia: September 2004, Vol. 43, No. 5, pp. 529-542.
 Ortiz Montoya EY. & al. Production of Chlorella vulgaris as a source of essential fatty acids in a tubular photobioreactor continuously fed with air enriched with CO2 at different concentrations. Biotechnol Prog. 2014 Jul-Aug;30(4):916-22. doi: 10.1002/btpr.1885.
Chlorella has been declared of national interest by the Japanese government.