TMG (trimethylglycine, betaine)
Summary
TMG (betaine) donates methyl groups that convert homocysteine back to methionine. In healthy adults, 1.5 to 6 g a day lowered homocysteine (grade B), and a meta-analysis found small strength gains in exercisers (grade C). The same 4 g+ doses raised total cholesterol in a meta-analysis. Prescription betaine is approved for the rare disorder homocystinuria.
Key facts
- A methyl donor that diets supply at about 0.5–2 g a day[2]
- Lower homocysteine in healthy adults (B); muscular strength (C); body fat (C); a rise in total cholesterol at 4 g/day or more (meta-analysis)[1][2][3][4][5]
- At least 4 g/day for 6 weeks or more lowered homocysteine by about 1.2 µmol/L in a meta-analysis of 5 trials[1]
- At least 4 g/day for 6 weeks raised total cholesterol by about 0.34 mmol/L (13 mg/dL) in a meta-analysis of 6 trials[4]
- Betaine anhydrous powder (Cystadane) is an FDA-approved drug for homocystinuria, a rare inherited disorder[7]
- 4 graded human outcomes on this page
- October 11, 2026
How it works
EstablishedBetaine donates a methyl group that converts homocysteine back to methionine, which is how prescription betaine lowers homocysteine in homocystinuria.[7]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Heart | Grade B | Improved | RCT · n = 76 · 2003 | 1 row |
| Performance | Grade C | Improved | Meta-analysis · n = 317 · 2024 | 1 row |
| Metabolic | Grade C | Improved | Meta-analysis · n = 195 · 2019 | 2 rows |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Fasting homocysteine at three doses | Improved | Grade B | RCT · n = 76 · 2003 Healthy men and women (4 groups of 19) Form: Betaine · Dose: 1.5, 3 or 6 g/day · Duration: 6 weeks Fasting homocysteine was 12%, 15% and 20% lower than placebo at 1.5, 3 and 6 g/day. | 14652361 (opens PubMed)Source [2] |
| Maximal strength and jumping | Improved | Grade C | Meta-analysis · n = 317 · 2024 Healthy people aged 15–60 in 17 placebo-controlled studies Form: Betaine · Dose: Varied (chronic use, at least 7 days) · Duration: At least 7 days Maximal strength improved (SMD 0.47, 95% CI 0.04 to 0.89), mainly lower body; vertical jump improved only after excluding a low-quality study. | 39514262 (opens PubMed)Source [3] |
| Body fat mass | Improved | Grade C | Meta-analysis · n = 195 · 2019 Adults in 6 randomized trials Form: Betaine · Dose: Varied across trials · Duration: Varied across trials Total body fat fell by 2.53 kg and body fat percentage by 2.44 points; body weight and BMI did not change. | 31623137 (opens PubMed)Source [5] |
| Metabolic syndrome risk factors in healthy adults | No effect | Grade D | RCT · n = 63 · 2011 Healthy young adults Form: Betaine in mineral water · Dose: 4 g/day · Duration: 6 months Little effect on metabolic risk factors; homocysteine lowering was weak, and plasminogen activator inhibitor 1 rose with betaine. | 20978525 (opens PubMed)Source [6] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Betaine anhydrous (TMG) | Varies[2][4][3] | No head-to-head human absorption data between forms in our sources.[2][4][3] | Generally well tolerated in trials; doses of 4 g/day or more raised total cholesterol.[2][4][3] | Homocysteine (1.5–6 g/day), strength (chronic use), body composition |
| Betaine hydrochloride | Varies[2] | Not compared in our sources.[2] | Not studied in the trials we cite.[2] | Sold as a stomach-acid aid; not the form used in the homocysteine or exercise trials |
Studied doses
Doses studied in human trials ranged from 1.5 to 6 g of betaine a day for 1 to 26 weeks; homocysteine fell at every dose tested from 1.5 g/day.[2][1][3][6]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- People watching their cholesterol
- Doses of 4 g/day or more raised total cholesterol in a meta-analysis of 6 trials.[4]
- CBS-deficiency homocystinuria
- In this disorder, prescription betaine can raise methionine to levels linked with brain swelling; it is used only with methionine monitoring.[7]
- Pregnancy and breastfeeding
- No safety data for supplemental doses in pregnancy were found in the trials we cite.[2]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Where to buy TMG (trimethylglycine, betaine)
Products from brands we partner with that contain TMG (trimethylglycine, betaine). Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.
- SupersmartPaid linkTMG (Trimethylglycine)3 tablets: 2,250 mg betaine anhydrous (750 mg per tablet); 33 servingsShop at Supersmart (opens in new tab)Price and label checked 2026-10-11 on the brand’s site.
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Frequently asked questions
Does TMG lower homocysteine?
Yes in healthy adults: 1.5–6 g a day lowered fasting homocysteine by 12–20% versus placebo over 6 weeks.[2][1]
Is TMG the same as betaine?
Yes. Trimethylglycine and betaine (betaine anhydrous) are the same compound; betaine HCl is a different product.[2]
Does TMG raise cholesterol?
A meta-analysis found 4 g a day or more raised total cholesterol by about 0.34 mmol/L.[4]
Does betaine help strength?
A meta-analysis of 17 studies found a small gain in maximal strength, mainly lower body.[3]
Sources
- [1]Betaine supplementation decreases plasma homocysteine in healthy adult participants: a meta-analysis.. J Chiropr Med, 2013. meta-analysis
- [2]Low dose betaine supplementation leads to immediate and long term lowering of plasma homocysteine in healthy men and women.. J Nutr, 2003. RCT
- [3]Effects of chronic betaine supplementation on exercise performance: Systematic review and meta-analysis.. J Sports Sci, 2024. meta-analysis
- [4]Betaine Supplementation Moderately Increases Total Cholesterol Levels: A Systematic Review and Meta-Analysis.. J Diet Suppl, 2021. meta-analysis
- [5]Effect of Betaine on Reducing Body Fat-A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. Nutrients, 2019. meta-analysis
- [6]Long-term effect of betaine on risk factors associated with the metabolic syndrome in healthy subjects.. Eur J Clin Nutr, 2011. RCT
- [7]CYSTADANE (betaine anhydrous for oral solution) prescribing information. DailyMed, U.S. National Library of Medicine, 2026. label
What changed
- Effect arrows corrected on 2 row(s): outcomes where a harmful measure fell (pain, symptoms, blood pressure, lipids, glucose, risk) now show as improved (up). No study data changed.
- First draft. Every PMID checked against NCBI E-utilities (title, year and journal taken from the PubMed record; retraction and expression-of-concern flags checked: none) and abstracts read for each cited row. Product details in Where to buy read from the brand page on the date shown.