Betaine
Also known as: Trimethylglycine, TMG, Betaine anhydrous
The methyl-donor molecule from beets — evidence for homocysteine and liver support, with a sweet-salt taste and a big name.
In short
Betaine (trimethylglycine, TMG) is a naturally occurring methyl-group donor first isolated from sugar beets. It performs two well-defined jobs in the body: it donates a methyl group to convert homocysteine back to methionine (lowering blood homocysteine), and it acts as an osmolyte that protects cells — especially liver and kidney cells — from osmotic stress. Clinical trials show betaine at 3–6 g/day reliably lowers plasma homocysteine, and prescription-grade betaine (Cystadane) is FDA-approved for the genetic condition homocystinuria. It is also widely used for nonalcoholic fatty liver, with promising but still-developing trial data. At high doses it raises LDL cholesterol in some people, a real and under-discussed caveat.
- Trimethylglycine; methyl donor from beet-derived discovery
- Lowers homocysteine reliably at 3–6 g/day
- Prescription form (Cystadane) treats homocystinuria
- Can raise LDL at high doses; osmolyte support in liver and kidney
What is Betaine?
Betaine is the quiet engine of the methylation cycle. Every cell that needs a methyl group — to make creatine, repair DNA, or recycle homocysteine — may borrow one from betaine, and the molecule is so central that a prescription form exists for the genetic disease where homocysteine runs wild. For everyone else, betaine's appeal is more modest: dependable homocysteine lowering, a plausible role in fatty liver, and an osmolyte effect that helps cells weather stress. The catch is the LDL effect — at supplement doses, cholesterol can climb in susceptible people, which is why betaine deserves respect rather than casual megadosing.
Where it comes from
Natural sources
- First isolated from sugar beets (hence the name, from Beta vulgaris)
- Dietary sources: wheat bran, spinach, quinoa, beets
- Body can synthesize it from choline
How it's made
White crystalline powder; supplement doses 500 mg–6 g; prescription Cystadane for homocystinuria.
What it does in products
Benefits
Homocysteine lowering
strong evidenceRandomized trials show 3–6 g/day reduces fasting and post-meal homocysteine by 10–20%, more in people with high starting levels.
Homocystinuria treatment
strong evidenceFDA-approved (Cystadane) for this rare genetic disorder; reduces homocysteine and associated complications.
Nonalcoholic fatty liver support
moderate evidenceSeveral trials find betaine improves liver enzymes and steatosis markers; meta-analyses are encouraging but limited by small samples.
Side effects & safety
Safety considerations
- Insufficient data at supplement doses; discuss with a clinician.
- None well documented; betaine complements — rather than competes with — folate and B12 in homocysteine metabolism.
- Not for: Hyperlipidemia at high doses (monitor LDL)
How it's used
In supplements
500 mg–3 g/day for general methylation support; homocysteine trials used 3–6 g/day. Prescription dosing for homocystinuria differs and is physician-managed.
In skincare
Cosmetic betaine (a different compound — trimethyl glycine used as humectant) appears in skincare at 1–5%.
Regulatory status
- Sold as a dietary supplement; prescription betaine (Cystadane) is FDA-approved for homocystinuria.
- Cosmetic betaine assessed as safe.
Popular products containing Betaine
- NOW TMG (Trimethylglycine) — 1,000 mg tabletsNOW Foods · Supplement
- Jarrow Formulas TMG — 750 mg capsulesJarrow Formulas · Supplement
- Cystadane (betaine anhydrous) — Prescription betaine powderRecordati · OTC drug
Product names and brands are shown for reference and belong to their respective owners.
The methylation connection
Betaine's methyl group converts homocysteine to methionine via BHMT, a pathway that operates independently of folate and B12. Because homocysteine is an independent cardiovascular risk marker, betaine offers a third lever — alongside folate and B12 — for pulling it down. Whether homocysteine lowering itself reduces event risk remains debated, but the biochemical effect is undisputed.
The LDL caveat
Betaine increases hepatic methylation, which can upregulate VLDL synthesis — several trials report LDL increases of 5–15% at 4–6 g/day, though some find no change. For healthy users at 1–3 g/day the effect is usually small, but anyone with dyslipidemia should monitor lipids while using betaine.
Frequently asked questions
Is betaine the same as betaine HCl?
No — betaine HCl is betaine bound to hydrochloric acid, used for stomach-acid support. Plain betaine (TMG) is a methyl donor and osmolyte; they are different tools.
Should I take betaine instead of folate for homocysteine?
They work in parallel, not as substitutes. Most clinicians address homocysteine with folate/B12 first; betaine is a useful addition, especially where those are already optimized.
Does betaine interact with choline?
They are metabolically linked — betaine is derived from choline and can spare it. Supplementing both is common in methylation-support stacks but rarely necessary.
The bottom line
Betaine is a legitimate, evidence-backed methyl donor with dependable homocysteine lowering and a growing fatty-liver dossier — best used at moderate doses with an eye on LDL.
References
- Betaine supplementation and homocysteine: meta-analysis. PubMed Central. https://pubmed.ncbi.nlm.nih.gov/25541215/
- Betaine in nonalcoholic fatty liver disease. PubMed. https://pubmed.ncbi.nlm.nih.gov/24327049/
- Betaine — Linus Pauling Institute Micronutrient Information. Oregon State University. https://lpi.oregonstate.edu/mic/other-nutrients/betaine