For those with MTHFR, if supplements are needed, it makes sense to take them in already-methylated form, so B6 as pyridoxal-5-phosphate, folate as methyl tetrahydrofolate, B12 as methyl cobalamin. Also, make sure you're getting sufficient methyl donors (choline, betaine). Even non-essential creatine makes sense as it's otherwise produced internally, which uses up methyl donors.

Sub optimal methylator here, had to figure this out...