This article is not intended to be used as medical or healthcare advice. Before you start any health related regimen, seek the guidance and advice of your Primary Care Physician or M.D.
There is a minority of folks who have adverse reactions to methylated b vitamins and methyl donor supplements (glycine, phosphatidyl choline, etc).
I have noticed some genetic patterns with these folks, as noted below:
Generally no mutations on MTHFR C677
Single or no mutations on MTHFR1298c
Most often 1 or more significant mutations on GMAT (guanidinoacetate methyltransferase, involved in the production of creatine)
Perhaps some mutations on AGAT (involved in creatine production)
Relatively few mutations on SLC19a1 and DHFR - both related to folate
It is generally accepted that around 70% of methylation capacity is used to generate phosphatidyl choline and creatinine under normal living conditions, the rest is consumer to process histamine, neurotransmitters, toxins, etc. Given GMAT is involved in the production of creatinine, if these folks have lower demands for creatinine, it would be plausible a lower creatinine demand would lead to lower need for methylation - which could make these folks sensitive to over methylation.
What does over methylation look like?
Well, for some, you may recall the term 'roid' rage - from steroid use - this term also was applied to people (mostly athletes and body builders) who took large amounts of creatinine to build muscle. Well, you can see how more exogenous creatinine could be useful and also result in over methylation - as their body's organic needs to produce creatinine fell away and they became over methylated.
My favorite non methylated B vitamin is B Minus by Seeking Health for just this reason. It has no methyl folate, nor methyl b12.
Niacin is often used to calm over methylation symptoms down, and serine can work well too - as it consumes folate to convert serine into glycine.
There are many other factors related to methylation before starting any particular regimen, but this topic has come up a fair amount with folks over the last 2 weeks, so I wanted to share some basics about it.