TIENS UK Spirulina. Spirulina is very rich in protein-the protein content in dry matter is about 70 %. It is a source of vitamins such as e.g.A (the vitamin is mainly present in the form of the precursorβ-carotene 700-1700 mg/kg),B1, B2, B3, B6, B12, C, D, E, K, but it is also a source ofmagnesium, potassium, phosphorus, copper, chromium, manganese, selenium, sodium as well aszinc.