Betaine (TMG)
The backup methyl donor. When your folate pathway is struggling, TMG steps in to keep methylation running—converting homocysteine and supporting liver function.
What Betaine/TMG Does
Methyl Donation
TMG = Tri-Methyl-Glycine. Three methyl groups ready to donate.
Homocysteine Recycling
BHMT enzyme uses TMG to convert homocysteine → methionine.
SAMe Production
Methionine becomes SAMe—the universal methyl donor.
Liver Protection
Prevents fatty liver by helping export fat from liver cells.
Osmolyte Function
Protects cells from osmotic stress, especially in kidneys.
Athletic Performance
May improve power output and body composition.
Two Ways to Recycle Homocysteine
Folate Pathway (MS/MTR)
Methylfolate + B12 → Methionine Synthase → converts homocysteine to methionine
- • Active throughout body
- • Requires MTHFR, B12, folate
- • Impaired by MTHFR mutations
Betaine Pathway (BHMT)
TMG → BHMT enzyme → converts homocysteine to methionine
- • Mainly in liver and kidneys
- • Independent of MTHFR
- • Backup when folate pathway fails
If you have MTHFR mutations, the BHMT pathway becomes more important—TMG can compensate.
Who Benefits Most from TMG
MTHFR Mutations
TMG bypasses the broken pathway, keeps methylation going.
High Homocysteine
TMG directly lowers homocysteine via BHMT.
Fatty Liver
TMG is lipotropic—helps liver export fat.
Poor Methylfolate Response
Some don't tolerate methylfolate—TMG is an alternative.
Low Choline Intake
Body makes TMG from choline—low choline = low TMG.
Athletes
May improve power, reduce fatigue, support body composition.
Food Sources of Betaine
Beets
~130mg per cup (highest source)
Spinach
~165mg per cup cooked
Quinoa
~175mg per cup cooked
Wheat Germ
~400mg per 100g
Supplement doses typically 500-3000mg. Hard to get therapeutic amounts from food alone.
TMG vs Other Methyl Donors
TMG (Betaine)
- • Works via BHMT in liver
- • Bypasses MTHFR
- • Gentle, well-tolerated
- • Good for liver support
Methylfolate
- • Works via MTR throughout body
- • Requires functional B12
- • Can cause overmethylation
- • Addresses root cause if folate-deficient
SAMe
- • Direct methyl donor
- • Fast-acting
- • More stimulating
- • Can cause anxiety in sensitive
Considerations
- • TMG converts to DMG (dimethylglycine) after donating a methyl—DMG has its own benefits
- • High doses may raise TMAO in some people (gut bacteria dependent)—controversial
- • Start low (500mg) and increase gradually
- • Works best with adequate B vitamins, especially B6 and B12
