Betaine (Trimethylglycine, TMG): Roles, Sources, Homocysteine and Evidence
Betaine (trimethylglycine, TMG): how the body makes and uses it, food sources, effects on homocysteine and cholesterol, exercise and liver research, and how betaine HCl is a different product.
Content last updated . This page has not been medically reviewed.
Betaine is a compound the body makes from choline and also gets from food. It is often sold under the name trimethylglycine or TMG; none of the sources read define that name, so this page uses "betaine". As a supplement, trials have measured mostly blood markers such as homocysteine. Betaine HCl is a different product with a different purpose, covered near the end. This page is information only. A clinician or pharmacist can say whether any betaine product suits a person, especially with a medical condition or medicines.
What betaine is and what it does
Choline is irreversibly oxidized to betaine in two steps, mainly in the liver and kidney. Betaine is an osmolyte (it helps cells manage water balance) and a methyl group donor. As a methyl donor it helps convert homocysteine back into methionine. [1] How it connects to folate and B12 is on homocysteine, folate and B vitamins. For the nutrient it is made from, see choline.Food sources
The review that tabulated US food data lists betaine alongside choline. Amounts there are small for the foods listed (mg per 100 g): beef steak, cooked, 13.0; chicken breast, cooked, 6.4; beef liver, cooked, 5.6; salmon, cooked, 1.8; egg, hard boiled, 0.6. [1] That table covers few foods, so a ranking of the richest betaine sources: Proper evidence not found in the sources read. Official intake levels (AI or UL) for betaine: Proper evidence not found. The Health Canada choline table read here does not list betaine. [2]What research found
| Question | What the source found | Label |
|---|---|---|
| Homocysteine in healthy adults | A meta-analysis of five randomized placebo-controlled trials (betaine of at least 4 g a day for 6 to 24 weeks) found a pooled fall in blood homocysteine of 1.23 micromol/L. [3] | Biomarker change only |
| Lower amounts | A 2022 meta-analysis found homocysteine fell by 1.30 micromol/L, and a subgroup analysis suggested amounts under 4 g a day lowered it without the lipid rise seen at higher amounts. [4] | Biomarker change only |
| Cholesterol | Meta-analyses found total cholesterol rose: by 0.34 mmol/L in six trials at 4 g a day or more [5]; by 14.12 mg/dl for total and 10.26 mg/dl for LDL in another meta-analysis, with no effect on triglycerides, HDL or blood pressure. [4] | Evidence of an effect on blood lipids |
| Heart disease outcomes | Proper evidence not found. Searches of PubMed returned marker studies, not trials of heart attack or stroke. | Insufficient evidence |
| Muscle strength and exercise | A 2024 meta-analysis of 17 studies (317 people) found better maximal strength, especially lower body; no significant effect on upper-body strength, sprint power or endurance. [6] | Promising but limited |
| Body composition | A meta-analysis found no beneficial effects on body mass, fat mass or fat-free mass. [7] | No good evidence of benefit |
| Fatty liver (MASLD) with raised ALT | Three small pilot trials of 1, 2, 4 and 8 g a day for 12 to 24 weeks compared before and after values; liver blood markers fell at 2 g and above but not at 1 g, and about 35 percent reported mild, transient stomach or bowel symptoms. [8] | Promising but limited (pilot, no placebo group described) |
Study amounts above are not advice, and benefits found in a trial of one group (for example athletes, or people with liver enzyme elevation) do not transfer to others.
Prescription use in homocystinuria
Betaine anhydrous is used as a medicine under specialist care in homocystinuria, a group of inherited disorders of homocysteine handling. In an observational registry of 125 children and adults treated for 7.4 years on average, alongside other therapies, plasma homocysteine fell by a mean of 29 percent, and betaine was reported as well tolerated. [9] This is a medical treatment decided and monitored by specialists; it says nothing about supplements for healthy people. Do not self-treat high homocysteine; see vitamin B12 testing.Betaine HCl is not the same product
Betaine hydrochloride is described in a 2024 narrative review as a short-acting acidifying agent available over the counter in capsule form. [10] It is promoted for stomach acid, a different goal from the homocysteine and exercise research above, and the studies above were of betaine itself, not betaine HCl. Evidence that betaine HCl relieves digestive symptoms: Proper evidence not found. A PubMed search for controlled trials returned case reports and narrative reviews only. Safety of betaine HCl with ulcers, acid-reducing medicines or anti-inflammatory medicines: Proper evidence not found in the sources read, so ask a clinician or pharmacist first.Related
Choline overview · Folate (B9)Frequently asked questions
Is betaine the same as TMG?
TMG (trimethylglycine) is a name commonly used for betaine on supplement labels, but none of the sources read define it; check the ingredient list. Betaine HCl is described as a different product. [10]
Does betaine lower homocysteine?
In healthy adults, trial meta-analyses found small falls in blood homocysteine. [3] [4] Whether that changes health outcomes is not shown.
Can betaine raise cholesterol?
Meta-analyses found total cholesterol rose, mainly at higher study amounts. [5] [4]
Does betaine help exercise performance?
A 2024 meta-analysis found better maximal strength, mainly in the lower body, with no clear effect on endurance. [6]
Is betaine HCl the same as betaine?
No. Betaine HCl is described as an acidifying agent. [10] Evidence that it helps digestion: Proper evidence not found.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: established nutritional role / treatment under medical care, promising but limited, mixed, insufficient evidence, marketing claim, Proper evidence not found.
Safety and who should ask a clinician
- Cholesterol: the rise in total cholesterol and LDL in trials means people with high cholesterol or heart disease should discuss it with their clinician. [4]
- Side effects: stomach or bowel symptoms in about a third of pilot-trial participants. [8]
- Medicines: Proper evidence not found in the sources read. See medication interactions.
- Pregnancy, breastfeeding, children, kidney or liver disease, surgery: Proper evidence not found in the sources read for supplement safety. Ask your care team and tell the surgical team about all supplements.
- Quality: labels vary; see quality testing.
References
- Dietary Choline Intake: Current State of Knowledge Across the Life Cycle. Nutrients 2018 (review). Read 2026-10-23.
- Health Canada. Dietary reference intakes tables: Reference values for vitamins. Page dated 2025-11-19; the choline values are the US and Canada Dietary Reference Intakes. Read 2026-10-23 through a web-fetch tool.
- Betaine supplementation decreases plasma homocysteine in healthy adult participants: a meta-analysis. J Chiropr Med 2013. Read 2026-10-23.
- Effects of betaine supplementation on cardiovascular markers: A systematic review and Meta-analysis. Crit Rev Food Sci Nutr 2022. Read 2026-10-23.
- Betaine Supplementation Moderately Increases Total Cholesterol Levels: A Systematic Review and Meta-Analysis. J Diet Suppl 2021. Read 2026-10-23.
- Effects of chronic betaine supplementation on exercise performance: Systematic review and meta-analysis. J Sports Sci 2024. Read 2026-10-23.
- Betaine supplementation fails to improve body composition: a systematic review and meta-analysis. Br J Nutr 2022. Read 2026-10-23.
- Pilot trials of oral betaine in participants with metabolic dysfunction-associated steatotic liver disease and elevated alanine aminotransferase. Hepatology 2026 (pilot trials). Read 2026-10-23.
- Betaine anhydrous in homocystinuria: results from the RoCH registry. Orphanet J Rare Dis 2019 (observational registry). Read 2026-10-23.
- Creating a Framework for Treating Autoimmune Gastritis-The Case for Replacing Lost Acid. Nutrients 2024 (narrative review). Read 2026-10-23.