Well, I just found a real nugget at mthfr.net - a quick & easy test to see if you're overmethylated (and need to take a non-methylated version of B12 like hydroxycobalamin) or whether you're undermethylated, and desperately need methylcobalamin, the methylated form of B12.
Ready? Here goes:
Rudimentary Methods to Understand if You’re Hypomethylated or Hypermethylated
2. Take some Niacin in the form of nicotinic acid. Chew 1/10th a tablet of Niacin and then swallow. Niacin utilizes s-adenosylmethionine (SAM) when breaking down. If you flush strongly on 50 mg, you are likely hypomethylated (lack of SAM). If you do not flush much, you are likely a ‘normal methylator’ (balanced SAM). If you do not flush at all, you may be hypermethylated (excessive SAM).
3. Side Effects from Methylfolate: If you are taking methylfolate and experiencing these side effects, then you are likely hypermethylated.