Skip to content

Printed from https://bottledhope.co/supplements/betaine/. Last reviewed 2026-09-24. Check the site for the latest version.

Betaine (TMG)

A compound in beets, spinach and seafood, also called TMG, sold as a supplement. Trials have tested it for homocysteine, body fat and endurance.

Explained simply · Last reviewed

What it is

Betaine is a small compound that the body makes and that many foods contain. Its chemical name is trimethylglycine, shortened to TMG. The FDA-approved label for a prescription form of betaine says it is a metabolite of choline, and that small amounts are found in foods such as beets, spinach, cereals and seafood. A 2025 review of endurance studies adds that it was first isolated from sugar beet in the 19th century.

More about Betaine (TMG)

Its chemical name is trimethylglycine, shortened to TMG. The FDA-approved label for a prescription form of betaine says it is a metabolite of choline, and that small amounts are found in foods such as beets, spinach, cereals and seafood. A 2025 review of endurance studies adds that it was first isolated from sugar beet in the 19th century.

The same review describes three roles for betaine in the body, and two of them matter here. It is an osmolyte: a molecule that helps cells keep their water balance under osmotic stress. It also hands a methyl group to homocysteine, turning it into the amino acid methionine. That second role is why homocysteine comes up so often below.

In the US, betaine is classified as a dietary supplement and is available without a prescription, according to the authors of a 2026 liver study. In a 2017 opinion, EFSA, the EU food safety authority, records the statement of a company applying to add betaine to sports foods: that betaine food supplements were already sold in the EU and used by sports people. A 2019 review of body fat trials notes that betaine has been used in animal feed to reduce carcass fat, and that data from humans were rare.

A prescription form is used under specialist care for a rare inherited condition, and the safety section describes it. Betaine hydrochloride, sold as a digestive aid, is a different product, and none of the research on this page is about it.

Also known as: TMG, trimethylglycine, betaine anhydrous

At a glance

Safety: known risks and 1 group who should avoid it or take extra care. See Safety ↓

Claims made about Betaine (TMG), and how strong the evidence is for each:

Each rating follows our published rules and the sources cited for it. We don’t add our own medical judgment. How we rate

Safety

Read this before the ratings below.

Risks

  • EFSA, the EU food safety authority, reports that "a significant increase in total and low-density lipoprotein (LDL)-cholesterol concentrations was noted at intakes of 4 g/day of betaine in overweight subjects with metabolic syndrome but not in healthy subjects, nor at intakes of 3 g/day." Taking the trials together, it considers that "the results indicate that 4 g/day betaine and above may increase total and LDL-cholesterol concentrations".
  • An earlier EFSA opinion states that "daily doses of betaine ≥4 g may significantly increase total and LDL-cholesterol concentrations in the blood." Elsewhere in the same opinion it describes the rise at "doses of 6 g per day" and says the effect "does not appear to be significant at lower daily doses (≤4 g per day)", so its two statements overlap at 4 g a day.
  • A 2013 meta-analysis of homocysteine trials notes that in two of its trials "betaine supplementation significantly increased total serum cholesterol and low-density lipoprotein (LDL) cholesterol". Its author judged those changes "small and of minor clinical significance", but also wrote that "the unfavorable effects on serum lipids with betaine supplementation may undo the favorable homocysteine-lowering effects".
  • Assessing betaine as a novel food ingredient for sports foods, EFSA concluded that "the safety of the NF, betaine, at the intended uses and use levels as proposed by the applicant (2.5 g/day) has not been established." It considered "an amount of 400 mg/day of betaine (i.e. 6 mg/kg body weight (bw) per day for adults) in addition to the background exposure" as safe, for the target population of the application, "sports people above 10 years of age". EFSA derived that level from human data, "considering 4 g/day of betaine as a reference point and applying an uncertainty factor of 10 to account for interindividual variability".
  • In the same 2017 opinion, EFSA notes that a long-term rat study had shown platelet counts rising with dose, and that "no adverse effects on platelet counts were noted in human intervention studies with exposure levels of 4 g/day of betaine for up to 6 months".
  • In three small pilot trials in people with fatty liver disease, the authors report that betaine "was well tolerated" and that stomach and gut symptoms were mild and transient. The report gives two different figures for how common those symptoms were: "approximately 35%" in its abstract and "~25%" in its discussion.

Who should avoid it or take extra care

  • People with homocystinuria, a rare inherited condition: the FDA has approved a prescription betaine anhydrous product, Cystadane, "for the treatment of homocystinuria to decrease elevated homocysteine blood concentrations in pediatric and adult patients." Its label states that therapy "should be directed by physicians knowledgeable in the management of patients with homocystinuria", and warns that in people with one form of the condition (CBS deficiency), "Treatment with CYSTADANE may further increase methionine concentrations" and that "Cerebral edema has been reported in patients with hypermethioninemia, including patients treated with CYSTADANE". If you have homocystinuria, ask the doctor managing it before taking any betaine supplement.

Safety sources: Source [1]Source [2]Source [3]Source [4]Source [5]

What the evidence says

Each claim is rated on its own evidence. Ratings follow the scale on our methodology page.

  • Lowers blood homocysteine (a blood marker) Evidence rating: Moderate

    People take TMG hoping to bring down homocysteine, a blood marker.

    EFSA judged the link between betaine and normal homocysteine metabolism established, as trials consistently show lower levels; a 2013 analysis of five trials also found lower levels.

    This rating is about a blood marker, not about heart attacks or strokes. EFSA, the EU food safety authority, concluded in 2011 that "a cause and effect relationship has been established between the consumption of betaine and contribution to normal homocysteine metabolism". It noted that "human intervention studies consistently show a significant decrease in plasma concentrations of homocysteine following betaine administration."

    A 2013 meta-analysis pooled five placebo-controlled trials in adults, all with normal homocysteine at the start. It found a statistically significant reduction, which its author puts at 11.8% of baseline values. The author describes all five trials as in healthy adults, though EFSA describes one of them as in obese people on a low-calorie diet. The analysis had a single author, who searched one database and did the study selection and analysis alone. The author notes both as limitations, and reports no GRADE rating.

    The same author states that "no studies to date have concluded that betaine supplementation directly reduces the risk of developing cardiovascular disease and stroke", and that "in patients with normal plasma homocysteine levels, betaine supplementation may have a negligible effect on cardiovascular health". Both sources report that betaine can raise LDL cholesterol; see the safety section.

    Sources: Source [1]Source [2]

  • Improves body composition (body weight, body fat or lean mass) in adults Evidence rating: Evidence against

    People take TMG hoping it will help them lose body fat or build lean muscle.

    A 2022 review of 12 trials found no significant change in body weight, body fat or lean mass with betaine; a smaller 2019 review had reported less body fat.

    Two meta-analyses disagree; this page shows the lower rating. A 2022 review of 12 randomized trials in adults found no statistically significant change compared with placebo in body weight, BMI, body fat percentage, fat mass or fat-free (lean) mass. The authors write that "our findings suggest that betaine supplementation does not improve body composition indices", and that it "may not be effective" for these measures. They add that only three trials were in people with overweight or obesity, and call for longer, high-quality studies.

    Each result rests on a smaller base than the review as a whole. Fat mass and fat-free mass each pool five comparisons from four trials, mostly young people in exercise training (two of them the Cholewa trials behind the earlier review's fat result), plus one trial in adults with a mean BMI of 33.5.

    The 2022 review's text says it "included five and seven trials" for fat mass and body fat percentage; its forest plots show five comparisons from four trials and seven from six. Body weight gets 56.8% of its weight from one trial of 27 people with prediabetes. Body fat percentage gets 45.7% from one trial. The authors found publication bias for body fat percentage and ran a trim-and-fill analysis, which did not change the result.

    An earlier 2019 meta-analysis of six trials reported a significant reduction in fat mass and body fat percentage, with no change in body weight or BMI. Its fat results came from four trials. Its authors note that the only two trials reporting less body fat were by the same research group, in young, non-obese adults on exercise training programs. The 2022 review explains the difference partly by the trials it added. The 2019 review lists among its funders the "2018 Chinese Nutrition Society (CNS) Nutrition Research Foundation-DSM Research Fund".

    Sources: Source [1]Source [2]

  • Improves endurance exercise performance Evidence rating: Insufficient

    Endurance athletes and other active people take it hoping to keep going longer or harder before they tire.

    A 2025 review found five small studies, all at high risk of bias, and called the evidence on betaine and endurance limited and inconclusive.

    Too little research to say. A 2025 systematic review found five small placebo-controlled studies, four of them randomized, with 101 participants in total. It judged all five at high risk of bias. Its discussion states that only two showed significant improvements, one in maximal oxygen uptake and one in mean power in the final stage of a sprint test. Its results section reports, for example, no significant difference in time to exhaustion in some studies and no effect on a 2 km rowing test in another.

    Its abstract reports a statistically significant result of some kind for all five studies, while its discussion counts two as improving endurance performance.

    The authors did not pool the results. They describe the evidence as "limited and inconclusive", and say the findings "highlight the paucity of evidence regarding the ergogenic potential of betaine in endurance exercise performance".

    Sources: Source [1]

  • Improves fatty liver disease Evidence rating: Insufficient

    People with fatty liver disease take it hoping it will reduce the fat and injury in their liver.

    The only cited evidence is three small 2026 pilot trials with no placebo group, in which blood markers of liver injury fell from the start of treatment at three of the four daily amounts tested.

    Too little research to say, and this page cites no systematic review that reports a result for betaine on its own. The cited evidence is a 2026 report of three small pilot trials in 70 people with fatty liver disease and raised levels of the liver enzyme ALT. Their disease was diagnosed clinically, rather than by biopsy. Blood markers of liver injury, including ALT, fell from the start of treatment at three of the four daily amounts tested but not at the lowest.

    None of the three trials had a placebo group. The authors compared one group with placebo participants from a separate, earlier trial, and note that such comparisons "have methodological limitations".

    Six of the authors disclose employment by, and in some cases stock in, Rubió Metabolomics or Nordic Bioscience.

    Sources: Source [1]

Sources

  1. Scientific Opinion on the substantiation of health claims related to betaine and contribution to normal homocysteine metabolism (ID 4325) pursuant to Article 13(1) of Regulation (EC) No 1924/2006
    EFSA Panel on Dietetic Products, Nutrition and Allergies (EFSA Journal), 2011 · Health authority summary · Primary source
  2. Betaine supplementation decreases plasma homocysteine in healthy adult participants: a meta-analysis
    Journal of Chiropractic Medicine, 2013 · Meta-analysis · Primary source
  3. Betaine supplementation fails to improve body composition: a systematic review and meta-analysis
    British Journal of Nutrition, 2022 · Meta-analysis · Primary source
  4. Effect of Betaine on Reducing Body Fat—A Systematic Review and Meta-Analysis of Randomized Controlled Trials
    Nutrients, 2019 · Meta-analysis · Primary source
    This source discloses industry funding.
  5. Effects of betaine supplementation on endurance exercise performance: a systematic review
    Physical Activity and Nutrition, 2025 · Systematic review · Primary source
  6. Pilot trials of oral betaine in participants with metabolic dysfunction-associated steatotic liver disease and elevated alanine aminotransferase
    Hepatology, 2026 · Trial without a placebo group · Supporting source
    Some of its authors disclose ties to industry.
  7. Safety of betaine as a novel food pursuant to Regulation (EC) No 258/97
    EFSA Panel on Dietetic Products, Nutrition and Allergies (EFSA Journal), 2017 · Health authority summary · Primary source
  8. Cystadane (betaine anhydrous for oral solution) prescribing information
    U.S. Food and Drug Administration (Drugs@FDA, NDA 020576), 2018 · Health authority summary · Primary source

Page history

Show all 3 changes to this page
  • — Rewritten to the content style guideline; ratings unchanged. Corrected the source type of the 2026 fatty-liver pilot trials from a randomized controlled trial to a trial without a placebo group; they were already counted as supporting evidence only, so no rating changed.
  • — Published. All four rated claims, the safety section and every source passed the site's source and wording reviews over two revision rounds. Unread reviews on muscle strength, lipids and fatty liver stay logged in docs/08-open-decisions.md.
  • — First drafted. Homocysteine (a blood marker) rated moderate, body composition rated evidence-against, endurance performance and fatty liver rated insufficient. Muscle strength and power is not rated: the reviews on it could not be read in full.