Spirulina contains 55-70% biologically, complete protein content by dry weight - which translates to 2 grams of protein per teaspoon - and it is also a source of beta-carotene, various minerals, and gamma linolenic acid, an essential omega-6 fatty acid. Spirulina naturally contains varying levels of phycocyanin, a pigment-protein complex with antioxidant properties that is found only in blue-green algae.