Supplement
TMG (Betaine)
A methyl donor that wins its biomarker and inherits that biomarker's null outcome verdict.
TMG (trimethylglycine, also called betaine) is a compound from beets, spinach, and quinoa that donates methyl groups in the liver, converting homocysteine back to methionine. We grade TMG (Betaine) C on evidence and C for worth-it at about $10-18 per month.
Evidence
Worth it
Typical cost: $10-18/month
What it does
TMG (trimethylglycine, also called betaine) is a compound from beets, spinach, and quinoa that donates methyl groups in the liver, converting homocysteine back to methionine. It is sold for homocysteine support, liver health, and athletic performance, and appears in many longevity stacks, often alongside the NAD-pathway supplements whose methylation cost it is said to offset.
What the research says
Lowers homocysteine reliably, by roughly 10 to 20 percent at gram doses
Evidence: moderate. Betaine is a methyl donor in the same remethylation pathway as folate and B12. Controlled trials and their meta-analyses show dose-dependent homocysteine reductions, larger in people with higher starting levels. As this library's B-complex record establishes, lowering homocysteine has not translated into fewer cardiovascular events in the big outcome trials, so the biomarker win is real and its value is unproven in the same breath.
May slightly raise LDL cholesterol, the counter-signal in its own trials
Evidence: emerging. Meta-analyses of betaine supplementation find small increases in total and LDL cholesterol alongside the homocysteine effect. A supplement traded for heart health that nudges LDL upward has to carry that fact in its benefit list, not only in fine print.
Sports performance and liver fat claims rest on small, mixed trials
Evidence: weak. Power and body-composition trials of TMG are small and split between positive and null. In fatty liver disease, an early pilot suggested histological improvement and a larger follow-up did not confirm a clear benefit. Neither use is established.
TMG does the thing it advertises, biochemically: it donates methyl groups and homocysteine falls, dose-dependently, in controlled trials. The problem is the destination of that fact. The homocysteine hypothesis has already had its outcome trials, in the B-vitamin literature, and they were null; a second road to the same biomarker inherits that verdict until someone runs an outcomes trial for TMG itself. Add a small LDL increase traveling in the opposite direction, thin performance data, and the grade is C: a real effect in search of a proven use.
The week's longevity and biohacking news.
This grade for TMG (Betaine) rests on the record above. When a new result changes that record, the grade changes with it, and the Thursday email is where the change lands first: the week's longevity and biohacking news, in plain English, linked back to the reasoning on this page.
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Every grade follows a published rubric, and sponsors never change one. When the evidence moves a grade, Thursday is where you hear it first, before you renew a stack that stopped earning its cost.
Is it worth it?
Evidence (C) sits below the leaderboard floor, so the worth-it grade is capped at C+ however inexpensive it is; the derived value lands at C. About $14 a month at trial doses. Derived from the October 2026 worth-it model.
Typical cost
$10-18/month
Common form, not a brand recommendation
Dosage context established
Homocysteine trials used 1.5 to 6 g/day, with most of the effect present by about 4 g; sports trials used about 2.5 g/day. Food sources are concentrated in beets, spinach, quinoa, and wheat germ, at a few hundred milligrams per serving, an order of magnitude below trial doses. TMG powder is hygroscopic and tastes sweet; none of that is evidence.
Worth-it leaderboard
TMG (Betaine) sits outside the worth-it top 20.
TMG (Betaine) sits outside the current top 20 on the gated leaderboard. The leaders below clear an evidence floor of B- before price counts at all, so cheap alone never earns a rank.
See the full worth-it leaderboard →
When the evidence moves a grade, this ranking moves with it. Thursday is where you hear it first.
Safety notes
Generally well tolerated; fishy body odor is reported at higher doses (a trimethylamine effect, the same pathway that makes some people sensitive to choline). The LDL increase noted in the benefits is the main medical caution: people supplementing for cardiovascular reasons should know their lipids moved is a possibility, not a paradox. Gastrointestinal upset occurs at the top of the dose range. Pregnancy data are absent.
Longevity Lab Report
TMG (Betaine) news. Graded when it happens.
The grade on this page stays free. The email carries the news on tmg (betaine): expert moves, dose changes, and what is working, in plain English every Thursday.
Changelog
Last updated 2026-10-23
- 2026-10-23|Graded from the homocysteine trial meta-analyses, the lipid counter-signal inside the same literature, and the performance and liver trial bases. Filed as its own record, distinct from this library's betaine HCl record (a digestive aid, a different compound with a different use), per the queue's explicit instruction not to conflate them.
- 2026-10-23|Not listed under any goal: the graded homocysteine finding is a biomarker without outcome data behind it in this record, and it does not earn a heart listing on its own under the library's assignment rule.