I recently bought an advanced b-12 complex from source naturals and it has adenosylcobalamin & methylcobalamin being around 5 mg. I've heard of the cyano and the methyl but the adenosyl I've never heard of?? well, since source naturals is one of my favorite brands as their vitamin b-12 supplements are always easily dissolvable and don't leave any wheat or gluten grainy taste afterwards(which happened with me with the vitamin shoppe brand.) Since it is my favorite brand I wouldn't expect them to put something useless in a b12 supplement. this b12 complex also has folate, which I also could need.