When rats eat a poor diet that lacks certain nutrients, their livers get fatty—but giving them betaine (a natural compound) helps keep the fat out, probably because it lowers a harmful chemical called homocysteine in the liver.

Giving betaine to rats helps their livers get rid of excess fat, and this works partly because it brings back two important chemicals—methionine and SAM—that help the liver function properly.

Taking betaine supplements may raise levels of betaine and some related compounds in your blood, slightly increase your 'bad' cholesterol, and lower a harmful substance called homocysteine — but it’s not clear if this is good or bad for your health.

When rats take betaine supplements, their livers make more of a special enzyme that helps clean up a harmful chemical called homocysteine, so less of it builds up.

Taking betaine supplements doesn't change the level of choline in your blood, which means your body doesn't use betaine to make or use choline right away.