Spirulina is another algae like chlorella, but with a more ancient tradition of use, having been a food source for the Aztecs and other Mesoamericans. Spirulina is notable for both its content and quality of protein. When dried, spirulina contains up to 70% protein by weight. In addition, it can be categorized as a complete protein because it contains all the essential amino acids, which are those that humans cannot synthesize and need to acquire by diet. It also contains a high amount of B-vitamins, iron, manganese, and is rich in more than a dozen other vitamins and minerals.