Lecithin is an oily substance belonging a group of nutrients known as phospholipids, which are water-soluble compounds composed of fatty acids, phosphorus, and nitrogen. The fatty acid portion of lecithin consists of linoleic acid or a combination of linoleic and linolenic acids, both of which are essential in the human diet. The phosphorus portion of lecithin is in the form of phosphatidylcholine (PC), and the terms "lecithin" and "phosphatidylcholine" are used interchangeably in medical literature. PC is generally considered to be the most beneficial compound found in lecithin because it is a rich source of choline, a member of the B-vitamin complex involved in many vital biological functions.
Dietary sources of choline are found primarily in the form of phosphatidylcholine from lecithin. Good sources of lecithin include liver, red meat, whole grains, legumes, and egg yolks (in fact, the term "lecithin" is derived from the Greek word for egg yolk, lekithos). Free choline (without the phosphatidyl group) is found in whole grains, liver, soy, and in some vegetables (especially cauliflower and cabbage). Supplemental sources of PC labeled as "lecithin" usually contain 10-20 percent PC. More concentrated supplements (containing about 35 percent PC) are usually labeled as "phosphatidylcholine." Other supplemental forms of choline include choline salts such as choline bitartrate, citrate, or chloride.
Choline is a crucial component of acetylcholine, a neurotransmitter essential for normal brain function. Phosphatidylcholine is a key structural component of cellular membranes and also plays an important role in the transport of fats throughout the bloodstream. As a constituent of bile, PC helps prevent fatty buildup in the liver and maintain gallbladder function.
The recommended dosage for lecithin varies according to its PC content and its intended use. Consult a nutritionally-oriented healthcare professional to determine the appropriate dosage. Many people prefer lecithin or PC concentrates over choline salts because high doses of choline may cause gastrointestinal discomfort and a "fishy" odor. In addition, research indicates that lecithin may be more effective than choline salts in raising serum choline levels. There is currently no evidence that lecithin or choline salts are toxic to humans.