I'm suggesting you purchase all the b vitamins individually, instead of in a complex, and experiment. Consider co-enzymated forms, but don't take the source naturals...because it is complexed. As for the question of taking them separately or combining them, there are some b vitamins that should be taken separately to avoid competitive inhibition of absorption. I am not totally sure about all the potential absorption issues or how significant the inhibition is, but here are some that I can recall: B1 inhibits B3 absorption Biotin inhibits B5 absorption I think B1 can be taken with B2, and I certainly don't see any contraindication for taking B9 with B12. I will let others chime in on this subject, but like others, I found that B2 has obvious absorption/competition issues when combined in a complex.