People vary in how they activate B6. The pyridoxine in standard vitamins is the inactive form --pyridoxine HCl. This is activated in the liver and blood cells to pyridoxal phosphate, which is the form the muscles use. If one does not metabolize this properly due to genetics or damage to the enzyme (some drugs block this conversion) the pyridoxine builds up. It is not known why it is not excreted properly either. For some reason autistic kids show elevations with no supplements. This is not understood either, at this time (I put that paper up here).
Not much is known about B6...I've searched for years to find usable information about it to post here. Not many doctors even test for it.
The actual number of cases of high dose toxicity are very few and mostly gathered from the days when PMS treatments involved 500mg or more a day. There are a couple of papers on PubMed describing rare reactions to B6 doses in the 50-100mg range daily. But they are very few...less than 5-- I could even find.
This problem is complicated by the fact that PN symptoms when B6 is low are the same as for when it is high. How can one tell which is the cause and which is the effect? Until someone gets funding to research this, all we have is anecdotal reports.
However, Dr. Bruce Ames who researches mitochondrial issues, aging and cancer, has published his opinion, that people vary genetically in how they use the B vitamins and hence what works for one person may not work for another.
B6 does not work alone in the nerves. B12 and folic acid work with it.
CMT is a special case, and you'd have to check out their websites to see what they recommend for P5P type of B6. In general, none of the toxicity papers mention what type of B6 caused the problem. Some say pyridoxine. P5P is a special form, which was not common 10 yrs ago when I found it and started posting about it. I use it myself. Since those days, more people know about it, and it is even being investigated as a "heart drug" and the company doing so wants to take it off the OTC market so they can have exclusive rights to make money with it:
This link has more information about this situation by Big Pharma:
http://neurotalk.psychcentral.com/sh...ight=pyridoxal
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All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
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Weezie looking at petunias 8.25.2017
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