Im sure there is a lot more to it than whats currently known and am certainly open to new Science on the subject.
At the end of the day what ever causes seems to be reduced with continual high dose applications and when doses are missed the flush severity increases.
I remember the first time I popped 500mg, thought I was going to burst into flames! Now at 1g I occassionally only get a little tingle/warmth. If I miss a few doses the effects are greatly increased. Consistent doses keeps the flush subdued.