I was under the impression that it was until I read this
"Theoretically Trimethylglycine will make Sam-E, but it's not guaranteed, additionally it is a super methylator. If over methylation is a problem, then trimethylglycine may present a problem because when trimethylglycine loses a methyl group to homocysteine, it gets converted to dimethylglycine (DMG) and this would something to avoid with overmethylation."
I also read that it isnt as good as say Sam-E or methionine because it isnt sulfur based and high Hs need sulfur increases. Thoughts?