There is vitamin B1 which many of you already know. Nutrition is interesting to me so over time I discovered more about how it functions and how it can help with stuttering in some people. B1 can help with glucose oxidation and thus increase energy in body/brain and since everything in the body needs energy it can help wiht many things. If you go deeper you can find B1 megadosing, different types of B1 and lots of success stories. Elliot Overton is one of the main guys doing research with B1 and treating and reversing things like Alzheimer's and dementia. If energy can't be produced over time any degenerative diseases can happen and maybe people who stutter lacking energy in specific areas and that's why B1 can help. Another thing that will help with energy is the thyroid which controls metabolism which is basically energy. With an abundance of energy especially in the brain (your idea of increasing brain power) we can maybe improve stuttering. Another thing people in the B1 community pointed out is that adrenalin can play a part in stutter, because it's somehow related to glucose oxidation/energy and anti adrenaline drugs supposed to help some guy fix stutter.