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If you’ve read my post on NMN, this one is its natural companion. I take Longevity Box TMG 750mg, 99% pure trimethylglycine (betaine), 120 capsules specifically alongside my NMN, and have done for over a year, for a reason that I think is genuinely important for anyone taking NMN or another NAD+ booster to know about.
Why NMN and TMG go together
Here’s the mechanism, and it’s worth understanding rather than just taking on faith: when you supplement with NMN to raise your NAD+ levels, your body produces a byproduct called nicotinamide as part of that process. Clearing that byproduct relies on an enzyme that consumes SAM (S-adenosylmethionine) — your body’s main methyl donor — to do so. SAM is used in well over 200 different processes in the body, including DNA methylation and general cellular maintenance, so ramping up NAD+ metabolism with NMN creates an increased demand on your methyl-donor reserves as a side effect.
TMG replenishes that pool through an independent pathway — it converts homocysteine back into methionine via a route that doesn’t rely on folate or B12, effectively topping back up the methylation capacity that NMN supplementation draws down. In practical terms, that’s the case for taking TMG specifically if you’re already taking NMN, rather than as a supplement on its own merits alone.
What TMG does in its own right
TMG isn’t just a “patch” for NMN’s side effects, though — it has its own independent evidence base. Its role in converting homocysteine to methionine is directly relevant to cardiovascular health, since elevated homocysteine is associated with increased heart disease risk; a review found doses up to 4 grams daily meaningfully lowered homocysteine levels. There’s also some research (including a study in athletes) suggesting benefits for muscular strength and exercise performance, though that evidence is more mixed than the homocysteine findings.
Why I take it, and what I’ve noticed
I take one capsule of TMG every time I take an NMN capsule, which for me means alongside my morning and lunchtime doses. Over more than a year of doing this consistently, I believe it genuinely supports how effective my NMN routine is — it’s a supporting-cast supplement rather than something I’d expect to notice on its own, but I see it as an important part of doing NMN supplementation properly rather than skipping a step that matters.
How I take it
One capsule alongside each NMN dose.
A quick safety note
TMG is considered safe at doses well above what’s found in standard supplements, with digestive upset (diarrhoea, bloating, nausea) being the main reported issue at higher amounts. It’s not recommended for children or if you’re pregnant or breastfeeding, and as always, it’s worth checking with your doctor if you’re on regular medication, particularly anything related to homocysteine or methylation.
Should you try it?
If you’re taking NMN or another NAD+-boosting supplement, I’d genuinely consider TMG a sensible pairing rather than an optional extra — it’s addressing a real biochemical trade-off that NMN supplementation creates. If you’re not taking NMN, it still has a reasonable case for itself via homocysteine and cardiovascular support, just a less specific one.
