If you're more comfortable starting slow, that's fine, but do increase your dose to 500 mg per day as quickly as possible.  The World Health Organization recommends 500 mg thiamine HCl per day when deficiency is suspected.  Dr. Lonsdale had researched high dose thiamine for decades, and he has used higher doses, 1 to 3 grams in some cases.   Like I explained above, it's at that 500 mg level or higher that passive diffusion happens and thiamine can get into cells.  Inside the cells, thiamine turns the mitochondria back on.  Mitochondria produce energy the cells use to function.  I had been taking a multivitamin containing thiamine HCl regularly and still had become deficient. ...

Absolutely no danger of overdosing on the stuff.  Thiamine is nontoxic, and safe.  I had gotten to 1000 mg of Thiamine HCl a day at one point.   Do continue taking the multivitamin with the other B vitamins.  You may want to add a magnesium supplement because magnesium and thiamine make enzymes together.  I like Magnesium l-Threonate (Neuro-Mag by life extension).  You may want to add a B Complex in addition to the multivitamin (take them at different times).  All the B vitamins are water soluble.   With Thiamine HCl, there's a "magic moment" about 500 mg, where sufficient thiamine can get into the cells by passive diffusion, and the difference is amazing.  In...