Trimethylglycine plays an important role in the health of the cardiovascular system, and is used as a supplement to treat high homocysteine levels.

Homocysteine is an amino acid produced during metabolism of another amino acid, methionine. Homocysteine is regarded as a risk factor for heart disease and is implicated in other disease conditions such as atherosclerosis.

Trimethylglycine works very closely with choline, folic acid, vitamin B12 and S-adenosyl methionine (SAMe): all of these compounds function as "methyl donors" and are involved with the conversion homocysteine to the biologically safe L-methionine.

High homocysteine levels are also seen in those with homocystinuria, a rare inherited disorder of the metabolism of the amino acid, methionine; and in those with a more common form of the disorder, methylene-tetrahydrofolate-reductase deficiency.

Trimethylglycine may also have lipotropic (aiding in fat metabolism) and hepatoprotective (liver) activity, and is also used to increase the concentration of acids in the stomach.

Many wines also contain betaine, particularly less expensive wines that use beet sugar to increase the alcohol content.

Supplements of trimethylglycine are commonly extracted from sugar beets (Beta vulgaris).

Methylation is inhibited by inadequately functioning key enzymes, excessive protein and fat intake, poor diet, inadequate intake of methyl groups, coffee, alcohol or by smoking.