TMG Benefits: Homocysteine, Cholesterol and the Evidence

Quick answer

TMG benefits, in short: TMG, also called betaine or trimethylglycine, is a compound found in foods such as sugar beet. As a supplement it is mostly used to lower homocysteine, an amino acid in the blood that, when high, is linked to heart and vascular risk. The trials are consistent on that marker: at least 4 g a day for 6 or more weeks lowered homocysteine by roughly 1.2 micromoles per liter [1][2]. There is a catch. The same doses raised total and LDL cholesterol in some analyses [2][3], and we found no trial showing that lowering homocysteine with TMG improves health outcomes. Small gains in strength are possible [4], but TMG did not change body composition [5]. We rate the evidence C: reliable effect on a lab marker, mixed and unproven for health outcomes.

What is TMG (betaine)?

TMG is a small molecule that your body can use as a “methyl donor”, a helper in a process that clears homocysteine. People are interested in it for aging because methylation is thought to play a role in how cells age. A 2025 review said these ideas are plausible, but many of the supporting studies are animal or lab studies [6]. Supplements come as TMG powder or capsules.

TMG benefits: what might it help with?

Possible benefit	Rating	In plain words
Lowering blood homocysteine	Strong	Consistently lower in trials of at least 4 g a day (about 1.2 µmol/L lower) [1][2]. This is a marker, and we found no trial showing it improves health outcomes
Muscle strength	Promising	A meta-analysis of 17 studies found a moderate gain in maximal strength, especially in the lower body [4]
Muscular endurance	No clear benefit	No effect on muscular endurance in the same analysis [4]
Body composition or weight	No clear benefit	No significant change in body weight, fat mass or lean mass [5]
Blood pressure, blood sugar, CRP	No clear benefit	No significant effect in a meta-analysis [2]
Cholesterol	Mixed (caution)	Higher total and LDL cholesterol at doses of 4 g a day or more [2][3]
Living longer or “slowing aging”	Early	No human trial has tested this [6]

Ratings describe how good the research is, not a promise that it will work for you.

What the research says

• Homocysteine. A meta-analysis of 5 trials in healthy adults taking at least 4 g a day for 6 to 24 weeks found homocysteine fell by 1.23 µmol/L on average [1]. PubMed
• Heart markers. A larger 2022 meta-analysis found a similar homocysteine drop (1.30 µmol/L) but also higher total cholesterol (about 14 mg/dl) and LDL cholesterol (about 10 mg/dl). It found no effect on triglycerides, HDL, blood sugar, CRP or blood pressure. A subgroup analysis suggested doses under 4 g a day lowered homocysteine without the lipid effects [2]. PubMed
• Cholesterol. Another meta-analysis of 6 trials (at least 4 g a day) found total cholesterol rose by 0.34 mmol/L on average, with no significant change in LDL, HDL or triglycerides [3]. PubMed
• Strength. A 2024 meta-analysis of 17 studies (317 people, 21% female) found betaine improved maximal strength, especially in the lower body. It had no significant effect on muscular endurance [4]. PubMed
• Body composition. A meta-analysis found no significant effect on weight, fat mass or lean mass [5]. PubMed
• Aging. A 2025 review described possible links to methylation, muscle and bone, but much of the evidence is from animal studies [6]. PubMed

Amounts and how people take it

These are amounts used in studies, not recommendations.

• Form: TMG (betaine anhydrous) powder or capsules.
• Amounts in trials: at least 4 g a day for homocysteine in most trials [1][3]. Lower amounts may also work, based on one subgroup analysis [2], though that is not a firm finding.
• Safety view of a European regulator: in a 2017 assessment of betaine added to certain foods, the European Food Safety Authority (EFSA) considered 400 mg a day, on top of what you get from food, to be safe, based on increases in cholesterol seen at 4 g a day [7]. That assessment was about foods, not supplements.
• Length: the trials we cite lasted 6 to 24 weeks. Long-term effects are unknown.

TMG with NMN or NR?

We found no human trial testing TMG together with NMN or nicotinamide riboside (NR) in the sources used for this page, so we can’t say whether the combination does anything extra or is safe. The documented concern with TMG on its own is higher total and LDL cholesterol at doses of 4 g a day or more [2][3]. See our NMN and nicotinamide riboside pages for what is known about those.## Side effects, interactions and who should check first

What trials found

The main concern is higher cholesterol at doses of 4 g a day or more [2][3][7]. If you take TMG at these amounts, ask your doctor about checking your cholesterol.

Who should check with a doctor or pharmacist first

Check with a doctor or pharmacist first if you:

• take any regular medicine, especially cholesterol medicines, since TMG may raise cholesterol. We did not find trials testing the combination
• have high cholesterol or heart disease, or a condition that affects homocysteine, such as a B-vitamin deficiency or an inherited metabolic disease. Do not use TMG to self-manage a diagnosed condition
• are pregnant, breastfeeding or trying to conceive, or are under 18. We found no reliable safety data in these groups
• have kidney disease or another long-term condition.

Where to buy

Look for a label that states the amount of TMG (betaine) per daily serving, evidence of third-party testing, and compare products by price per daily dose rather than pack price. Our TMG (betaine) buying guide explains how we choose products. Note that studies use 4 g or more a day, which can take several capsules.

FAQ

What is TMG?

TMG, also called betaine or trimethylglycine, is a compound found in foods such as sugar beet. It is mostly used as a supplement to lower homocysteine, an amino acid in the blood that, when high, is linked to heart and vascular risk. Your body can use it as a “methyl donor”, a helper in clearing homocysteine.

Does TMG work?

Yes for a lab marker: at least 4 g a day for 6 or more weeks lowered homocysteine by roughly 1.2 micromoles per liter [1][2]. The same doses raised total and LDL cholesterol in some analyses [2][3], and we found no trial showing that lowering homocysteine with TMG improves health outcomes. Small strength gains are possible [4].

How much TMG per day?

Most homocysteine trials used at least 4 g a day [1][3]. In a 2017 assessment of betaine added to certain foods, the European Food Safety Authority considered 400 mg a day on top of food to be safe, but that was about foods, not supplements [7]. These are amounts used in studies, not recommendations.

Who should not take TMG?

Check with a doctor or pharmacist first if you take regular medicine (especially cholesterol medicines), have high cholesterol, heart disease, kidney disease or a condition that affects homocysteine, are pregnant, breastfeeding or trying to conceive, or are under 18. We found no reliable safety data in the last groups.

Can you take TMG with glutathione?

We found no human trial testing TMG together with glutathione, so we can’t say whether the combination does anything extra or is safe. The main concern with TMG is higher cholesterol at doses of 4 g a day or more [2][3][7]. Ask a doctor or pharmacist if you take other supplements or medicines.

Related pages

• NMN: another supplement people discuss alongside methylation
• Nicotinamide riboside: another NAD+ building block
• Glycine: another amino-acid supplement
• Our TMG (betaine) buying guide
• Longevity supplements for beginners: where this fits in a beginner’s routine
• All supplements A-Z

Talk to your doctor

This page is for general information and is not medical advice. Speak to a doctor or pharmacist before starting any supplement, especially if you are pregnant or breastfeeding, take any medicine, or have a health condition.

References

We cite only studies and official pages we checked against PubMed, the publisher or the agency’s own site. The A to E evidence grades are explained in our editorial policy. See also our medical disclaimer and affiliate disclosure.

1. McRae MP. Betaine supplementation decreases plasma homocysteine in healthy adult participants: a meta-analysis. J Chiropr Med. 2013. PubMed · DOI
2. Ashtary-Larky D, Bagheri R, Ghanavati M, Asbaghi O, et al. Effects of betaine supplementation on cardiovascular markers: A systematic review and Meta-analysis. Crit Rev Food Sci Nutr. 2022. PubMed · DOI
3. Zawieja EE, Zawieja B, Chmurzynska A. Betaine Supplementation Moderately Increases Total Cholesterol Levels: A Systematic Review and Meta-Analysis. J Diet Suppl. 2021. PubMed · DOI
4. Zawieja E, Machek S, Zanchi NE, Cholewa J, et al. Effects of chronic betaine supplementation on exercise performance: Systematic review and meta-analysis. J Sports Sci. 2024. PubMed · DOI
5. Ashtary-Larky D, Bagheri R, Tinsley GM, Asbaghi O, et al. Betaine supplementation fails to improve body composition: a systematic review and meta-analysis. Br J Nutr. 2022. PubMed · DOI
6. Zawieja E, Chmurzynska A. Betaine and aging: A narrative review of findings, possible mechanisms, research perspectives, and practical recommendations. Ageing Res Rev. 2025. PubMed · DOI
7. Turck D, Bresson JL, Burlingame B, Dean T, et al. Safety of betaine as a novel food pursuant to Regulation (EC) No 258/97. EFSA J. 2017. PubMed · DOI