Biosynthesis and Metabolism of Choline

Sequential removal of the fatty acids by phospholipase action results in the formation of lysolecithin (glycerophosphorylcholine), then hydrolysis to release choline. Acetylcholine is synthesized in neurons using acetyl CoA. 

About 30% of dietary phosphatidylcholine is absorbed intact into the lymphatic system the remainder is hydrolyzed to lysolecithin in the intestinal mucosa and to free choline in the liver. Free choline in the diet is largely metabolized by intestinal bacteria, forming trimethylamine, which is absorbed and excreted in the urine. Only about 30% of free choline is absorbed intact. 

Choline can be used for synthesis of phosphatidylcholine by reaction between CDP-choline and diacylglycerol. Under normal conditions, the major pathway of phosphatidylcholine synthesis is by the incorporation of 

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