Betaine (TMG): Uses, Benefits, Dosage & Safety
Last updated: June 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
Quick summary
Betaine (TMG) reliably lowers homocysteine and has small, inconsistent benefits for athletic power — but trials show it can also raise LDL cholesterol, which complicates the heart-health rationale.
What is Betaine (TMG)?
Betaine, also called TMG (trimethylglycine), is a compound found in foods like beets, spinach and whole grains, and made in the body from choline. It acts as a methyl donor and a cellular osmolyte, helping cells manage water. It is sold both for heart-related homocysteine lowering and as a performance supplement for strength and power. A prescription form also treats a rare genetic disorder.
What Betaine (TMG) is commonly used for
In supplements, Betaine (TMG) is taken to lower homocysteine, to support strength and power in training, and for liver health. It is marketed for both heart and gym goals; the evidence offers a partial yes with an important caveat.
How Betaine (TMG) works
Betaine donates a methyl group to convert homocysteine back into methionine, which is how it lowers homocysteine levels. As an osmolyte it helps cells stay hydrated under stress, the proposed basis for its performance effects. Both mechanisms are real, but lowering homocysteine hasn't translated into proven heart benefits, and the performance effects are modest.
What the evidence says
Here's an honest snapshot of what published research suggests about Betaine (TMG) — including where the evidence is limited.
- A set of randomised, placebo-controlled trials found betaine lowers homocysteine but also raises LDL ('bad') cholesterol and triglycerides in healthy people — which could offset any cardiovascular benefit. (PubMed)
- General background is summarised by reputable health references; small sports-nutrition trials report modest improvements in strength or power around 2.5 g per day, but reviews call the performance evidence inconsistent. (MedlinePlus)
Typical dosage used in studies
Homocysteine studies often use 3–6 g per day, while performance studies use about 2.5 g per day; the higher homocysteine-lowering doses are also where the cholesterol-raising effect appears. This is general information from research, not a recommendation.
Side effects and safety
Betaine is generally well tolerated; possible effects include digestive upset and a fishy body odor at high doses. The notable concern is the rise in LDL cholesterol and triglycerides seen at higher doses, so people watching their lipids should be aware of it.
Medication interactions and who should avoid Betaine (TMG)
Medication & safety check
Betaine has few significant drug interactions, but because high doses can raise cholesterol, people with heart-disease risk or on lipid-lowering therapy should be cautious and monitor their lipids. The prescription form (for homocystinuria) is used under medical supervision.
This is general information, not personal medical advice. If you take any medication, confirm it's safe to combine with Betaine (TMG) with your doctor or pharmacist first.
Sources & further reading
The evidence summary above is drawn from these sources. For general, authoritative background you can also consult:
- PubMed-indexed study (PMID 15916468)
- MedlinePlus
- NIH Office of Dietary Supplements
- NIH National Center for Complementary and Integrative Health
Frequently asked questions
Does betaine (TMG) improve workout performance?
Some small trials show modest strength or power gains around 2.5 g per day, but the evidence is inconsistent, so expectations should be modest.
Does betaine lower homocysteine?
Yes, reliably — but lowering homocysteine with supplements hasn't been shown to reduce heart attacks or strokes, and betaine can also raise LDL cholesterol.
Is betaine the same as betaine HCl?
They're related but used differently: betaine (TMG) is the methyl-donor supplement here, while betaine HCl is taken for stomach acid; check the label.
Is betaine safe?
Generally well tolerated, but higher doses can raise LDL cholesterol and triglycerides, so monitor your lipids if you take it.
How much betaine is used?
About 2.5 g per day in performance studies, 3–6 g per day in homocysteine studies. This is general information, not a recommendation.
Where you'll find Betaine (TMG)
Betaine (TMG) is not a lead ingredient in the product categories we currently review, but you can browse every supplement we cover to see how ingredients like this fit into full formulas. See the full supplement guides index.
Related ingredients to explore
Ingredients often studied or formulated alongside Betaine (TMG) — useful for understanding the full picture of a formula.