I took B vitamins, D, and some other supplements very early on but couldn't say if they helped or not. I took them as a precaution.
Exercise absolutely helped me. Scientific evidence for it as well. Not so much for the supplements.
As Dee mentioned, time has helped more than anything. One thing I experienced the first couple of years, which was upsetting to me, was a struggle to find words. And for me, that seemed devastating. I actually would struggle in normal, everyday conversation to name common objects such as chair, broom, cup, mop, dog, cat. It bothered me so much that I'd damaged myself, truly damaged my brain. But I want to say that this has gotten way better with time. Additionally, and surprisingly, words I knew years ago (and had not used in a while) seemed to come to me from out of nowhere at the perfect moment. My vocabulary wasn't lost. It was just hidden in there, in the recesses of the brain.
So, take heart that in time things will get better. You can make sure to hydrate, sleep, exercise, and eat a balanced diet. The B vitamins seem to be a good idea, but of course, any supplement should be taken cautiously and probably with a doctor's approval.
Note: I am 3.5 years sober.