I believe it was Gina that mentioned the fillers so she should credit.
As for the B vits the cofactors are really just the tip of the iceburg so I dont bother with the ATP cofactors.
Optomix brand is 100mg riboflavin and 500 niacin. Which is a healthy dose but personally I dont feel I need 100mg B2 and 500mg niacin isnt enough.
What I do is focus on my core B's individually and then take a complete B complex to fill in the gaps.
Source natural (brand very important) 5mg B12 methylcobalamin 10mg a day let dissolve between cheek and gum. That insures best absorbtion.
Solgar niacin (plain niacin that causes a flush) 1000mg 3x a day.
Solgar Methylfolate 800mcg
Jarrow B-right b complex 1 a day. I really havent noticed much from this product by itself but the 3 above have really helped me in many ways. Most B complexes that I have looked at contain poor forms of B12 and folate, often times what I would consider poor forms of niacin as well so as I mentioned this is just kind of to fill the gaps.