Spirulina is a blue-green algae found in the oceans and in alkaline lakes of Africa, Mexico, and South America. It occurs as filaments less than 1 mm long, consisting of transparent cells stacked end-to-end, taking on the spiral shape for which the algae is named. Often billed as a "superfood," dried spirulina is an excellent source of protein and also contains vitamins, minerals, and essential fatty acids. Most commercially available spirulina is cultivated in immense artificial ponds at Lake Texcoco, Mexico.
A typical recommendation for spirulina consumption is three 1 gram servings per day, with meals. Spirulina appears to be very well tolerated, with no known side effects. Animal studies have found no signs of toxicity for spirulina, even at very high intakes.