It's not Hydroxocobalamin or folate because they will tend to increase methylation.
Niacin and Niacinamide is what you are looking for. Niacin will cause skin flushing whereas Niacinamide will not.
I got very good results with 250mg Inositol Hexanicotinate capsules but they are more expensive than Niacinamide which I mainly use. They tend to eliminate the tongue coating making it a more smooth reddish colour.
Start low and don't overdo it. because you might not need any more than 200mg, I certainly don't if I overdo B12/Folate and TMG.