I take 1-2 capsules of Probutyrate a day when needed, it’s a delayed release form of butyrate and it really helps me. In my experience you might feel a bit of bloating and brain fog the first few days of it, but it gradually gets much better. Some other things that help me are certain ADHD meds (which I refuse to take anymore) and low sugar/dairy. Certain mitochondrial supplements like coq10, alcar, and pqq tend to help. Taurine was helping for a while before I started feeling stomach discomfort from it. Also DAO supplements when I feel high histamine loads after eating too many fermented or probiotic foods. But overall taking care of the gut seems to have the most consistent benefit to stuttering for me.