TMG (Trimethylglycine)
Also known as Betaine, Betaine anhydrous, Glycine betaine
Trimethylglycine (TMG), also called betaine, is glycine carrying three methyl groups. Despite the shared backbone, its role is quite distinct from plain glycine: it is primarily a methyl donor. Through the BHMT enzyme it remethylates homocysteine into methionine, a folate- and B12-independent route, which is its best-established benefit. TMG also acts as a cellular osmolyte, supports liver fat metabolism, and has growing (if mixed) evidence for improving strength and power output in athletes.
Benefits
Lowers homocysteine
StrongBetaine reliably reduces fasting and post-methionine homocysteine by donating a methyl group to convert it back to methionine via BHMT, an alternative to the folate/B12 pathway. This is its strongest, most consistent effect.
May improve power and strength
PreliminaryAround 2.5 g/day has improved power output, strength, and body composition in several resistance-training trials, though results across studies are inconsistent.
Supports liver fat metabolism
PreliminaryAs a methyl donor and osmolyte, betaine aids VLDL export from the liver and has been studied for non-alcoholic fatty liver disease (NAFLD).
Cellular osmoprotection
PreliminaryBetaine stabilises proteins and cell volume under osmotic, thermal, and exercise-induced stress.
Pros & cons
Pros
- Distinct mechanism from glycine, a true methyl donor
- Folate- and B12-independent route to lower homocysteine
- Cheap and well tolerated at the studied 2.5 g dose
- Evidence spanning cardiovascular markers and athletic performance
Cons
- Can modestly raise LDL/total cholesterol at higher doses in some studies
- Performance evidence is mixed
- High doses may cause a fishy body odour
Side effects
Fishy body odour at high doses
Excess methylamine production can cause a fishy odour, more likely above ~6 g/day or in people with TMAU.
GI upset
Nausea, bloating, or diarrhoea can occur at higher doses.
How to take it
Typical dose
2.5 g/day for performance; 3–6 g/day studied for homocysteine
Timing
With meals; performance studies often split it into two daily doses
Common forms
Tip: Use betaine anhydrous for methylation/performance goals. Do not confuse it with betaine HCl, which is taken to raise stomach acid.
What the research says
Betaine and homocysteine
StrongBetaine supplementation lowers plasma homocysteine in a dose-dependent manner via BHMT-mediated remethylation, independent of folate status.
Betaine and athletic performance
PreliminarySeveral RCTs report gains in power, strength, or body composition with ~2.5 g/day betaine, though findings are inconsistent across protocols.
How it connects
Relationships between TMG (Trimethylglycine) and other supplements in the matrix.
TMG provides a folate-independent route to remethylate homocysteine (via BHMT), complementing the folate/B12 pathway, useful when folate cycling is impaired.
Compare the pairingStructurally glycine plus three methyl groups, but functionally distinct: TMG donates methyls (becoming dimethylglycine) while glycine can accept them, together they help buffer methylation balance.
Compare the pairingBoth feed the homocysteine-methylation cycle through parallel routes; TMG can pick up remethylation when B12-dependent methionine synthase is limited.
Compare the pairingCreatine synthesis consumes a large share of the body's methyl groups; TMG helps replenish methylation capacity and both are studied for strength and power.
Compare the pairingFrequently asked questions
What is TMG (Trimethylglycine) used for?
TMG (Trimethylglycine) is most commonly used for heart health, energy, and liver health. Betaine reliably reduces fasting and post-methionine homocysteine by donating a methyl group to convert it back to methionine via BHMT, an alternative to the folate/B12 pathway. This is its strongest, most consistent effect.
How much TMG (Trimethylglycine) should I take?
A typical dose is 2.5 g/day for performance; 3–6 g/day studied for homocysteine. Use betaine anhydrous for methylation/performance goals. Do not confuse it with betaine HCl, which is taken to raise stomach acid. Start at the lower end and confirm the right dose for you with a healthcare professional.
When is the best time to take TMG (Trimethylglycine)?
Recommended timing: With meals; performance studies often split it into two daily doses.
What are the side effects of TMG (Trimethylglycine)?
Reported side effects include fishy body odour at high doses and gi upset. Excess methylamine production can cause a fishy odour, more likely above ~6 g/day or in people with TMAU.
Who should be careful with TMG (Trimethylglycine)?
May modestly raise LDL and total cholesterol at higher doses, monitor lipids with long-term use. Speak with a healthcare professional if any of these apply to you.
Important cautions
- May modestly raise LDL and total cholesterol at higher doses, monitor lipids with long-term use.
- Distinct from betaine HCl (a digestive aid); choose betaine anhydrous for methylation goals.
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