Betaine, also known as trimethylglycine, is an amino acid - so named because it was first discovered as a beet byproduct. It is also found in wheat, shellfish, and spinach.
It can be produced via choline oxidation. Betaine is a major methyl donor and acts as an osmolyte in the cell to regulate cell volume.
Betaine donates a methyl group, using the enzyme betaine homocysteine methyltransferase (BHMT), to re-methylate homocysteine back to methionine.
The product of this methyl transfer is dimethylglycine (DMG), which is then available for further methyl donation.
In folate deficiency, this betaine pathway compensates to maintain Homocysteine re-methylation. Folate-deficient people have elevated serum DMG levels, as would be expected with the increased betaine use as a methyl source.
Because the betaine pathway is a salvage pathway to remethylate Homocysteine, betaine is a significant determinant of plasma Homocysteine levels, particularly in folate deficiency.
Betaine supplementation lowers Homocysteine after methionine load.
References:
- https://pubmed.ncbi.nlm.nih.gov/24022817/
- https://pubmed.ncbi.nlm.nih.gov/18716669/
- https://pubmed.ncbi.nlm.nih.gov/20346934/
Betaine
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