An answer is yes. All changes to a formulation of beer affects the taste and keepability. Also any impurities, ie presevitives and additives massively increase the Hangover effect. A good example is red wine, the French Bordeau region increasingly added preservitives and other things to their wines untill they found it affected the drinker and the wine detrimentaly (?) and had to find new ways to produce the same wines that they had been producing, in some cases centuries, back to the core grape and region caracteristics that they had lost trying to supply the demand for the product. ( Patriotic flag waving here ) Australian wine makers were recruited to affect this as they were making "better" wine types with "inferior" methods! This was in the 80's so some posters may not be aware of this Yes I am "Old"
well then forget it, actually now that i think about, when I drink Budweiser, it does give me more of a hangover and is the only beer to ever make me throw up. If you look at the label on a bottle of Bud it says clearly that there are rice additives in it, so what you say does make sense. Allright, I've changed my mind! No thiamine in beer!