Phosphatidylcholine (PC), not to be confused with phosphatidylserine (another nootropic), is most commonly extracted from sunflower or soy lecithin. In mouse models of Alzheimer’s disease, Phosphatidylcholine improves memory  and function of acetylcholine, a critical brain neurotransmitter. In the same models, deficiency of PC leads to increased rates of nerve degeneration.
The main dietary source of PC is unprocessed lecithin that contains: phosphatidylcholine, phosphatidylserine (PS), phosphatidylethanolamine, phosphatidylinositol, and phosphatidic acid. Lecithin has nootropic properties, presumably due to Phosphatidylcholine and PS content, which are the most studied and well established nootropic phospholipids. In combination with omega-3 fatty acid DHA, Phosphatidylcholine improves learning and memory of young mice .
Phospholipids are essential components of the so-called “phospholipid bilayer”, which envelops every cell in the human body.
Mechanism of Action
As already discussed, Phosphatidylcholine is important for the nerve membrane and promotes nerve integrity. It is an essential phospholipid.
Most Phosphatidylcholine is integrated into cell membranes, but a portion is broken down into choline and a phosphatidyl group. Choline enhances nerve transmission by boosting acetylcholine function. Choline may be more useful in a case where a person is already deficient in choline, typically vegetarians. Beef and eggs are rich sources of choline and vegetables such as broccoli and Brussel-sprouts deliver a dosage of 50mg per cup.
The phosphatidyl group of Phosphatidylcholine usually attaches to a serine or ethanolamine group, which are also critical to cell membrane function, including mitochondrial membranes. The phosphatidyl group is also involved in the synthesis of sphingomyelin, which like myelin, is essential to the central nervous system. Deficiency in sphingomyelin contributes to systemic neurodegeneration. Phosphatidylcholine, along with naltrexone and a cholesterol-optimized diet, may have benefits in multiple sclerosis, which is a degeneration of myelin and nervous tissue .
It supports normal apoptosis and autophagy; a processes involved in the normal clearance of old brain cells and the clearance of cancer cells, or bacteria and virus infected cells. Enhanced turnover of cells may explain part of its nootropic qualities.
Benefits of Phosphatidylcholine
Food sources of choline include a ratio of phosphatidylcholine, so if one is deficient in choline, one also tends to be deficient in phosphatidylcholine. Therefore, supplementation can improve membrane integrity and acetylcholine levels. A deficiency in acetylcholine can cause a range of cognitive defects and problems. “Cholinergic” drugs, including acetylcholinesterase inhibitors, are often the first line of treatment against cognitive disorders such as Alzheimer’s Disease. Alternatively, one can stack citicoline with phosphatidylserine to a similar effect. Both stacks will increase phospholipid and acetylcholine levels.
Side effects or Risks
Large doses may increase triglyceride levels and risk of atherosclerosis. A portion of ingested phosphatidylcholine and its byproducts (created by gut flora) are eventually converted into triglycerides. Daily doses above 600mg may contribute to cardiovascular disease . According to WebMD, phosphatidylcholine can sometimes cause excessive sweating, upset stomach and diarrhea. Like other choline sources in high dosages, it can cause a fishy body odor (trimethylaminuria) in susceptible people.
 Administration of phosphatidylcholine increases brain acetylcholine concentration and improves memory in mice with dementia. Chung, et al. Jounal of Nutrition. 1995 June.
 Intakes of dietary docosahexaenoic acid ethyl ester and egg phosphatidylcholine improve maze-learning ability in young and old mice. Lim and Suzuki. Journal of Nutrition. 2000 June.
 HEALING the MEMBRANE – HEALING the BODY The Important Role of Phospholipids http://www.mwt.net/~drbrewer/HealMembraneHealBody.htm
 Mechanisms of apoptotic phosphatidylserine exposure. Marino and Kroemer. Cell Research. 2013.
 Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Wang, et al. Nature. 7 Apr 2011