Chlorella vulgaris is a green microalgae mainly used as a dietary supplement or protein-rich food additive in Japan. At the beginning of the 1990s, German scientists noticed the high protein content of C. vulgaris and began to consider it as a new food source. Japan is currently the largest consumer of Chlorella. The proteins content of C. vulgaris varies from 42 to 58% of its biomass dry weight. These proteins are considered as having a good nutritional quality compared to the standard profile for human nutrition of the World Health Organisation and Food and Agriculture Organisation, as the algae synthesises amino acids. The algae also contains lipids, carbohydrates (12–55% dry weight) and pigments with among others chlorophyll, reaching 1–2 % of the dry weight. C. vulgaris contains minerals and vitamins. Vitamin B12, specifically in the form of methyl cobalamin, has been identified in Chlorella vulgaris.