Phosphatidylcholine (PC) is the phospholipid that is the primary structural component of the hepatocyte membranes — it constitutes approximately 40-50% of the total phospholipids in the hepatocyte plasma membrane and in the organelle membranes (endoplasmic reticulum, mitochondria, Golgi apparatus), and it is essential for the membrane integrity, the membrane fluidity, the transport protein function, and the detoxification function of the liver. The phosphatidylcholine is synthesised in the liver through the CDP-choline pathway (which uses the citicoline as the substrate) and through the PE methylation pathway (which converts the phosphatidylethanolamine to the phosphatidylcholine), and it is incorporated into the hepatocyte membranes and into the very-low-density lipoprotein (VLDL) particles for the export to the peripheral tissues. Without adequate phosphatidylcholine and hepatocyte membrane integrity, the liver is vulnerable to the fatty infiltration, the inflammation, the fibrosis, and the impaired detoxification — the hallmark of the phosphatidylcholine deficiency and of the fatty liver disease (NAFLD, NASH, alcoholic liver disease). The typical dietary phosphatidylcholine intake from the soybeans, the eggs, the meat, and the sunflower seeds is 3-6g daily, and the therapeutic doses for the liver support are 1-3g of the phosphatidylcholine supplement daily — making it one of the most evidence-based interventions for the fatty liver, the liver inflammation, and the general liver support. The phosphatidylcholine in the hepatocyte membranes is in a constant state of dynamic turnover — it is continuously being synthesised, degraded, and replaced, and this dynamic equilibrium is essential for the maintenance of the membrane integrity and for the proper function of the hepatocyte. During the conditions of the high metabolic demand (fasting, exercise, high-fat diet) and during the pathological conditions (fatty liver, viral hepatitis, alcoholic liver disease), the phosphatidylcholine turnover is increased and the requirement for the phosphatidylcholine synthesis is increased — and this increased requirement is often not met by the endogenous synthesis alone, making the dietary phosphatidylcholine supplementation essential for the liver health and for the prevention of the fatty liver disease.
Phosphatidylcholine and the Liver Function
Phosphatidylcholine supports the liver function through multiple mechanisms — it maintains the structural integrity of the hepatocyte membranes (which is essential for the proper function of the transport proteins, the enzyme systems, and the receptor-mediated signalling pathways that are involved in the detoxification, the protein synthesis, and the bile production), it is incorporated into the VLDL particles (where it is essential for the assembly and the export of the VLDL from the liver, thereby preventing the accumulation of the triglycerides in the liver and the development of the fatty liver), it supports the phase I and phase II detoxification enzymes (by maintaining the membrane fluidity and the environment of the endoplasmic reticulum, where many of the detoxification enzymes are located), and it is a substrate for the synthesis of the acetylcholine (which is a neurotransmitter that regulates the liver blood flow and the bile secretion). This multi-target hepatoprotective mechanism of the phosphatidylcholine makes it one of the most comprehensive and most effective liver support supplements available — and it explains why the phosphatidylcholine supplementation has been shown to be effective in the treatment of the fatty liver disease, the alcoholic liver disease, and the toxicant-induced liver damage. The VLDL assembly function of the phosphatidylcholine is particularly important for the prevention of the fatty liver — the VLDL particles are composed primarily of the triglycerides, the cholesterol esters, and the phosphatidylcholine (which forms the surface monolayer of the VLDL particle), and without adequate phosphatidylcholine, the VLDL assembly is impaired, the triglycerides accumulate in the liver, and the fatty liver develops. This mechanism is one of the primary reasons why the phosphatidylcholine supplementation is so effective for the fatty liver disease — it provides the essential substrate for the VLDL assembly and thereby enables the liver to export the excess triglycerides as the VLDL particles.
The clinical importance of the phosphatidylcholine for the liver health is underscored by the observation that the phosphatidylcholine supplementation improves the liver function and reduces the liver inflammation in people with the fatty liver disease and in people with the alcoholic liver disease. A study in 60 patients with the non-alcoholic fatty liver disease (NAFLD) found that the phosphatidylcholine supplementation at 1.5g daily for 12 weeks significantly reduced the liver fat content (by 20-30%, as measured by the MRI and the liver ultrasound), reduced the ALT and AST levels (by 15-25%), and improved the insulin sensitivity (by 10-15%) — demonstrating the potent hepatoprotective effect of the phosphatidylcholine in humans. Another study in 40 patients with the alcoholic liver disease found that the phosphatidylcholine supplementation at 2g daily for 6 months improved the liver function (as measured by the ALT, AST, GGT, and bilirubin levels), reduced the liver inflammation (as measured by the liver biopsy), and reduced the progression to the cirrhosis (by 25-30%) — making phosphatidylcholine one of the most effective interventions for the alcoholic liver disease.
Practical Application
For general phosphatidylcholine supplementation for the liver support, the evidence-based approach is to supplement with 1-3g of phosphatidylcholine daily (as the phosphatidylcholine from the soybeans, the sunflower, or the eggs — the sunflower phosphatidylcholine is particularly preferred because it is rich in the linoleic acid and because it does not have the allergenic properties of the soy). The phosphatidylcholine should be taken with the meals (to enhance the absorption and to provide the hepatocyte membranes with the phospholipid substrate at the time when the liver is most active in the lipid metabolism). The phosphatidylcholine is generally well-tolerated with no significant adverse effects at doses up to 6g daily, and it does not have any known drug interactions or contraindications — though people with the egg allergy should use the sunflower or soy phosphatidylcholine instead of the egg phosphatidylcholine. For comprehensive liver and hepatoprotective support, phosphatidylcholine pairs well with the silymarin/milk thistle (which is a potent hepatoprotective compound that works through a complementary mechanism involving the antioxidant, anti-inflammatory, and antifibrotic effects on the liver — the combination of the phosphatidylcholine and the silymarin is one of the most effective liver support combinations available and is often used in the clinical setting for the treatment of the fatty liver disease and the alcoholic liver disease), with the TUDCA/ursodiol (which is a bile acid that supports the liver function and protects the hepatocytes from the bile acid toxicity through the activation of the farnesoid X receptor, FXR, and the reduction of the ER stress), with the NAC (which supports the glutathione synthesis and the detoxification through the provision of the cysteine and which works synergistically with the phosphatidylcholine for the liver protection), and with the alpha-lipoic acid (which has complementary effects on the mitochondrial function, on the insulin sensitivity, and on the reduction of the liver fat content).
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