The protein content of spirulina is high (50 to 70 g / 100 g of dry matter). Unlike other microorganisms offered as sources of protein (yeasts, chlorella …) spirulina does not contain cellulosic walls but a rather fragile envelope. This fact explains the excellent digestibility of spirulina proteins (83-90%).
Moreover, their composition is balanced with the presence of 8 essential amino acids (which cannot be produced by the body): isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Spirulina contains about 1 g / 100 g of Gamma-linolenic acid and can therefore be considered as one of the best known sources of this essential fatty acid, after human milk and some uncommon vegetable oils (evening primrose oils, borage, blackcurrant pips and especially hemp). The presence of γ-linolenic acid is to be emphasized because of its rarity in common foods and its high presumed food value. This fatty acid is a precursor of mediators involved in anti-inflammatory and immune processes.
Provitamin A (β-carotene): spirulina contains about 200 mg of β-carotene and about 100 mg of crypto-xanthine per 100 g of dry matter; these two carotenoids are convertible into vitamin A by mammals according to the needs (no risk of overdose). Since vitamin A requirements are estimated in adults at less than one mg per day, one to two grams of spirulina are largely sufficient to satisfy them.
Vitamins B: spirulina is rich in B vitamins (B1, B2, B6, B12). The active vitamin B12 intake could represent only about 20% of the quantity dosed (160-300 mg / 100 g) but this is still an interesting source. Vitamin B12 deficiency is common, due either to a lack of intake (case of strict vegetarian diets) or a lack of absorption. On the other hand, it seems that certain pathological conditions systematically lead to vitamin B12 deficiency, as is the case of HIV infections leading to AIDS.
Minerals and trace elements: especially interesting minerals in spirulina are: iron, calcium, phosphorus and magnesium:
The high iron content of spirulina (70-100 mg / 100 g) should be emphasized. In addition, this iron is highly absorbable in animals and humans (about 30-40% could be absorbed, or even more if spirulina is taken with vitamin C). In comparison, whole grains, which are among the best sources of iron in low-fat diets, contain only 150 to 250 mg / kg. In addition, cereals contain components that strongly limit iron absorption. In addition, iron supplements given as ferrous sulfate may be poorly tolerated by GI tract. Iron deficiency is widespread, causing anemia especially in pregnant women and malnourished children.
Calcium, phosphorus and magnesium are present in spirulina in amounts comparable to those found in milk. The relative amounts of these elements are balanced, which excludes the risk of decalcification by excess of phosphorus. It should be noted that regions with soils deficient in magnesium are common and cause deficient syndromes in the populations, including cardio-vascular and nervous disorders
Phycocyanin is a rare enough pigment in nature. Its concentration in spirulina is 10 to 11% on average. Appreciated as a natural blue dye in food industry, a lot of research is still ongoing to know all its properties. It possesses antioxidant and detoxifying properties. Phycocyanin also stimulates the body’s immune system.
For an exhaustive review of nutritional properties of spirulina, refer to the document: spiruline aspects nutritionnels J. Falquet et J.-P. Hurni, Antenna Technologies, 2006 (41 pages)