Spirulina is a blue-green microalgae that typically grows in freshwater lakes, natural springs, and saltwater in subtropical and tropical climates. It is often used as a vegan source of protein and vitamin B12. It is between 55-70% proteins, but studies suggest it is a subpar source of B12, as the vitamin is not absorbed well after ingestion.
Human evidence suggests that spirulina can improve lipid and glucose metabolism, while also reducing liver fat and protecting the heart. Animal studies are very promising as well, as spirulina has been shown to be of similar potency as commonly used reference drugs, when it comes to neurological disorders.