sandy1522, you may benefit from focusing on the B vitamins and magnesium. Thiamine requires magnesium to become bioactive and once activated it can activate B6. Magnesium is also needed to activate vitamin D. Thiamine is critically needed by the brain, gut and nervous system however anti thiamine factors diminish or destroy thiamine. A comprehensive list can be found in the stuttersence link. Water soluble thiamine forms don't pass the blood brain barrier as efficiently as fat soluble forms. The nootropicsexpert link explains further the fat soluble forms which benefit being taken with a meal. The B vitamins work better together and I encourage you to become familiar with the others. Also check out sublingual fast melt Methylcobalamin B12. It helps repair nerves. Always consult your health care provider before using any supplement.
http://stuttersense.blogspot.com/2014/08/these-factors-reduce-your-thiamine.html
https://nootropicsexpert.com/vitamin-b1-thiamine/