I remember (relative term) the first time a bunch of co-workers and I got rip roaring drunk on a keg of homebrew. We were all pleasantly surprised at how light the hangover was considering how totally wrecked we were. This was before the internet was real so the guy at the LHBS said it was because yeast trub has b vitamins and helped the liver metabolize the alcohol. I still haven't gotten totally f-ed up on mead YET so I don't know if that's true with mead as well.
I am not sure about the B-Vitamin connection with low to no hangovers (I'd be buying them in bulk if that were so!!!) But my experiences with alcohols of MANY types over many years (I am a former bar owner, restaurateur, comp tech, amatuer chef, and a few other well worn work hats and collars as well), is that with or without added B-Vitamins, amino acids, etc, of all types, I have never seen a "scientific study" done.
I have never heard of using them in alcoholic ferments, until now and on this site... so I have started researching this and other sites for their chemistry/biology/molecular chem/etc. So far the data is sparse to nil. But that all of my ferments have so far not had any real problems is pretty good I think.. but then again I am not [paid to think! In fact I am not paid at all...
YOUR tolerances for the aldehydes, esters, phenols, etc that are produced (flavors & aromatic compounds) and not mine or anyone elses, will lead you to YOUR preferences... Plus a ton of other variables, volatiles, fermentable, non-fermentables, etc.. that contribute to the complexity in ways that it will take me years, IF EVER, to BEGIN to understand!!!! The complexities of what is going on here with ferments of ALL types is so complex it is almost (ALMOST!!!) unpredictable. Mead, cyser, cider, melomel, etc are all VERY different, and just need individual TLC...
With any mead, melomel, etc... Mine, yours & others, JAOM, BOMM, Tupilo honey, OB honey, whatever! We all need to kibitz here and elsewhere so that we can create something that is at least in OUR (mine and my partners anyway) minds mouth, something that can be put into our mouths to affect out minds!!!
(Sorry, babbling again..)