Phosphatidylcholine is a required component of VLDL particles. Methyl groups from betaine may be used to convert homocysteine to methionine . Elevated levels of homocysteine in the blood have been associated with increased risk of cardiovascular diseases . When the supply of choline is inadequate, VLDL particles cannot be synthesized and fat accumulates in the liver ultimately resulting in liver damage. Elevated ALT activity is a sign of liver damage.
Liver damage appears to be the result of increased liver cell death.
This is referred to as de novo synthesis of choline. See diagram . Three molecules of SAM are required for the three methylations of phosphatidylethanolamine required to synthesize phosphatidylcholine. Once SAM donates a methyl group it becomes S-adenosyl homocysteine, which is metabolized to homocysteine . For more information on homocysteine and cardiovascular diseases, see Folic Acid.