Methionine and choline: moving fat out of the liver

The liver packs fat into particles called VLDL to send it out into the blood, and every VLDL particle needs phosphatidylcholine in its coat. Choline is the raw material for phosphatidylcholine, and methionine supplies SAM, the methyl donor the liver uses to make more of it. When either is short, fat gets stuck in the liver. These are the classic lipotropes: nutrients that move fat out of the liver.