Hi there - this is not an answer to your question, per se, so I will opt out and allow someone else to answer more directly. I just wanted to provide you with a caution - be careful with supplements/vitamins just like you would with other medications. Massive doses of niacin can cause flushing, sweating and is hard on the kidneys. Large doses of vitamin C can cause stomach cramping and diarhea. If you are contemplating taking the vitamins, it's best to do so under the care of a physician.
Also, as a psychologist, I cannot recommend Dr. Hoffer's method as the evidence supporting it appears anecdotal at best and potentially harmful at worst. Please be careful and research your options thoroughly.
I wish you the best.