How a vitamin-like compound helps livers stay fat-free

Taking a supplement called betaine can lower a substance in your blood called homocysteine, which is linked to a higher chance of getting Alzheimer’s—so this supplement might help protect your brain.

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.

Betaine, a natural compound, can stop a harmful substance (homocysteine) from blocking an important energy-sensing system in one type of liver cell, but not in another—because the first cell type has a special enzyme (BHMT) that the second one doesn’t have enough of.

When there’s too much homocysteine in your blood, it can mess up key energy sensors in your liver, making it harder for the liver to stop storing fat—so more fat builds up inside it.

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.