Organic Spirulina 500mg Tablets. (per tablet) Organic Spirulina ( Arthrospira ) 500mg. Spirulina is rich in antioxidant properties, which protects the body against harmful free radicals. It is rich in B Vitamins, Vitamin C and D and contains high levels of Iron, Iodine, protein, Beta-carotene, carbohydrates, Fibre and Selenium.