Spirulina 500mg 500 tabs from Source NaturalsSpirulina Tablets 500 mg Spirulina are blue green microalgae with high nutritional value. They are especially rich in protein, beta carotene, and chlorophyll, and provide one of the few natural food sources of vegetarian vitamin B 12. Supplement Facts for 500 mg Serving Size: 6 tablets Amount %DV Spirulina Plankton (Spirulina platensis) 3 g Yielding Approximately: Protein 1. 8 g 0. 03 Vitamin A (as beta carotene) 14000 IU 2. 8 Thiamin (vitamin B 1)