Trimethylglycine / TMG / betaine

Also known as TMG, betaine anhydrous, betaine, trimethyl glycine.

Last reviewed October 9, 2026 · Jump to references

What is Trimethylglycine / TMG / betaine?

In plain words

TMG is a substance found in foods such as beets and made by the body from choline, a nutrient. It helps cells maintain water balance and helps turn homocysteine into methionine, a building block for proteins. Researchers study it for lowering homocysteine and for possible effects on liver health and exercise performance. Evidence for broader health benefits is mixed, and it can cause stomach upset.

Technical definition

Trimethylglycine (TMG), also called betaine, is a zwitterionic glycine derivative with three methyl groups attached to its nitrogen; it occurs in foods and is produced in the body by choline oxidation. It acts as an osmolyte supporting cellular water balance and as a methyl donor for betaine–homocysteine methyltransferase, which converts homocysteine to methionine rather than acting through a receptor. In the United States, betaine is sold as a dietary supplement, and prescription betaine anhydrous is FDA-approved for treating homocystinuria.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.