You may have already heard or read that Spirulina is a great source of high-quality proteins, but what does it mean exactly?
A great part of the desirable nutritional value attributed to Spirulina is due to its high content of proteins that reaches around 60-70% of dry biomass. That is an exceptionally high proportion when compared to most plant food sources which contain, on average, 35% total proteins. It is, therefore, a very appropriate alternative to meet the recommended daily intake of 0,8 grams of proteins per kilograms of bodyweight per day. However, when assessing the nutritional protein value not only the quantity should be considered, but also qualitative aspects such as protein composition, digestibility, bioavailability of essential amino acids and the absence of toxicity and anti-nutritional factors.
In general, meat is the most common high-quality protein source in human and animal diet whereas plant-based diets may lack bioavailable and essential amino acids, unless highly diversified or supplemented. Luckily, Spirulina successfully attends very selective demands of protein quality as well. Its amino acidic profile is rich in essential amino acids and is very similar to that of the standard animal proteins albumin and casein, albeit the slightly lower values of branched-chain amino acids and of the sulfated amino acids methionine and cysteine (circa 80% of the standard animal protein values). Yet, as a very simple unicellular organism, the composition of Spirulina’s biomass can be modulated under controlled culture conditions and those values can get even closer to animal sources in general.
Such composition guarantees a complete bioavailability to human and animal ingestion, with no limiting factor for assimilation whatsoever. That is a remarkable feature for a vegetarian/vegan biomass! Recent studies show that the addition of relatively low amounts of Spirulina dry biomass (2-5%) on the dough of snacks and cookies results on a real improvement of the proteins quantity and quality of the final product without substantial modifications on its physical aspects such as taste, smell and hardness.