Not that I'm aware of. AFAIK, B-complex is a convenient way for many people to get minimum or better amounts of all the necessary Bs combined in one pill/caplet. Also, B-complexes come in different formulations/strengths, so it's a good idea to read the label and know exactly what & how much you're getting and what you're not. They're generally enough for most healthy folks, but for folks with particular needs (like PN) some of those amounts may not be enough; I take a B-complex, and supplement it with extra B5 & B12.

What they don't generally say on the labels is to take on an empty stomach, and when there's a choice (as with B1 vs. benfotiamine, cyano-B12 vs. methyl B12, etc.) they usually contain the cheapest version, which may not be the most bioavailable forms.

Doc