beer is a diuretic so adding vitamins would serve no purpose, you would pee them out as you would with regular beer
When you brew beer, the old fashioned way with malted barley, hops and other whole grains there are all kinds of vitamins/fiber/nutrients ect in the brew but the main ingredient that produces alcohol is the sugar. After you boil or brew your mix of malted grains with water to extract the sugar and flavors you want to filter out all the fiber/solids before you ferment this into beer. You want just the liquid left over from this brew. If you leave all that stuff in there when you add yeast you will have a big grainy goopy mess. There's a process to it, I've been making beer, wine, champagne and other things of and on for 20 years. Message me.