Chris MasterJohn writes some interesting posts on particularly the B vitamins, but also other things like Molybdenum.
My personal experience with B6 was that a dose of 100mg a day of the inactive form (probably pyroxidine) caused some tingling which I think was its self-inhibitory effect. I switched to p5p and have not had issues.
His argument is that CoA is sequestered by B6 and hence a large dose of B5 is a sensible approach.
I wonder anyway whether I should increase my B5 dosing because
a) It is a CoA precusor
b) It is in Royal Jelly.
However, I do take a lot of pantethine when drinking. There is an interesting question that I need to consider whether I encounter more tingling when not drinking (as I always take panethine when drinking). Various things cause tingling. Including beta-alanine.
Pantethine has the negative side effect of slowing up clotting, however.
The people who really suffered from B6 overdose were taking around a gram or more a day.
Twenty years ago, began experiencing tingling in my feet, most noticeable when taking a shower. I was taking 100 mg. B6 in a Life Extension multi-mix. Around that time research began emerging on the downsides of high dosed of B vitamins. I cut my daily dose in half and the tingling went away and has never returned.
Unless treating a specific condition, I now believe high dose B vitamins ill-advised even if not immediately harmful. Among other things, high exogeneous sources can in some cases blunt the metabolic uptake of more beneficial sources from food sources.