Spirulina is a blue-green algae and is believed to be one of the oldest forms of life on earth. Spirulina was first used by the Aztecs to increase stamina and is considered a superfood – a complete source of nutrients, including protein levels comparable to eggs. The Aztecs also used spirulina to treat various ailments, and legends say that the kingdom’s messengers used the algae to sustain their marathon runs. Modern research supports many of the claimed benefits of taking spirulina and continues to study its potential for treating health problems. Spirulina has a bitter taste, so people often mix it with yogurt, juice and smoothies to enhance the taste. Spirulina is widely available as a dietary supplement in health food stores.