Spirulina is actually one of the most nutrient-dense foods on the planet. Spirulina is 60% protein (that's more than two times the protein found in red meat), contains 18 amino acids, (including all essential amino acids), and 10 of the 12 non-essential amino acids. It's also a great source of many other essential vitamins and minerals including copper, iron, manganese, potassium, B vitamins, and iodine.