By entering my sex, height and weight and the times when I drank the drinks in the drinkR app I end up with this estimated BAC curve: (Now I might be totally off with what drinks I had and when but Romain Francois, Karl Broman, Sandy Griffith, Karthik Ram and Hilary Parker can probably fill in the details.) If you want to estimate your current BAC (or a friends) then head over to the drinkr app hosted at ShinyApps $$ where $C$ is the alcohol concentration, $A$ is the mass of the alcohol, $W$ is your body weight and $r$ is the Widmark factor
As detailed above, controlled human dose-ranging trials do not exist
DOI: 10.3390/antiox10030364
doi: 10.1046/j.1471-4159.1997.69062599.x
Getting the recommended Vitamin B12 and other nutrients through diet is the best way
Published protocol Mouse: 5 mg/kg intraperitoneal, repeated over weeks (Baar et al., 2017)