Spirulina is probably the least popular protein on this list but shouldn’t be forgotten. Spirulina is a green powder that is actually a type of cyanobacterium. Derived from seaweed, spirulina is often compared to whey protein powder due to similarities in consistency and use. Just one tablespoon of spirulina has an amazing 4 grams of protein. Since this is powdered, it is a good idea to add this protein to smoothies.