Imagine a supplement that could actually restore memory. Could we use it to reverse some of the memory loss that comes with aging? What if it could also enhance our ability to think?

The supplement that’s getting all this heady attention would seem, at first glance, to be a very unlikely candidate. Many of its effects have a lot more to do with digestion than with brain function. Yet there are components of lecithin that seem to play a critical role in nerve function—and our brains, of course, are nothing more or less than elaborate agglomerations of busy nerves making interesting connections with each other.

To see lecithin’s action up close, put a chocolate bar in the freezer. When you take it out some time later, you’ll notice that the whole bar is tinged with white.

You can chalk up that transformation to lecithin. Derived from soybeans and egg yolks, lecithin is often added to foods such as chocolate, cheese, margarine, and salad dressings. In these foods, it acts as an emulsifier, which simply means that it helps mix fats with water and keeps them from separating. When the chocolate bar is frozen, the lecithin-fat interaction falls apart. The fat rises to the surface, giving the candy that whitish tinge.

Choline is a nutrient that’s essential for helping to turn fat into energy within the liver. Although it’s a component of lecithin, it’s also sold separately as a supplement.

In addition to the way it helps the liver deal with fat, choline has another function: It helps transmit nerve impulses in the brain.

That transmission process isn’t quite as straightforward as carrying cellular e-mail from one address to another. Instead, choline is a building block of another chemical, acetylcholine, that actually carries messages between nerve cells. The brain uses acetylcholine for many purposes, including controlling memory, heart rate, and sweating, according to Dr. Zeisel.

Tantalized by the possibility that choline could help memory, researchers have been investigating the link. To date, they’ve found that acetylcholine is in short supply among some people who have neurological disorders, but that doesn’t prove that more acetylcholine produces better brain function.

Related research has led to a more promising path. Researchers have run across another chemical in lecithin called phosphatidylserine (PS). The scientists have found that PS, a building block for brain cells, seems to have a particularly beneficial effect on the production and release of the chemicals that transmit messages, according to Parris Kidd, Ph.D., a biomedical consultant in Berkeley, California, and author of Phosphatidylserine: The Nutrient Building Block That Accelerates All Brain Functions and Counters Alzheimer’s.

In fact, PS is the single best means for conserving memory and other higher brain functions as we age, says Dr. Kidd. In studies, PS has been shown to improve the quality of life for people with declining brain function. It improves function in people with mild to moderate Alzheimer’s and counteracts some of the age-related memory loss among people who don’t have Alzheimer’s. According to Dr. Kidd, it also has some benefits that go beyond memory function: helping people cope with stress and, in some individuals, helping to alleviate depression.

"PS seems to have a global effect on brain functions," he says. "It helps memory, learning and concentration, mood, and daily rhythms. It seems to have a general revitalizing effect on the brain."

The type of PS that’s been shown to work on memory is derived from bovine brain, says Alan Gaby, M.D., professor of nutrition at Bastyr University in Bothell, Washington. A soy-based PS is being tested, but the chemical structure is a little different, so we can’t assume that its effects are the same, says Dr. Gaby. So far, it has not been shown to be effective, he says.

Meanwhile, back in the digestive area, researchers can pinpoint many of lecithin’s benefits when it comes to transporting valuable resources from place to place in our bodies.

We are constantly secreting lecithin into our bile, says Dr. Zeisel, and that helps enzymes mix with fat so that the fat is digested.

The liver exports fat. To do that, it must wrap the fat in an envelope containing lecithin and certain proteins. When lecithin is unavailable, no envelope can be made, and fat accumulates in the liver. Liver cells low in lecithin fill up with fat and then die.

"Humans who are fed intravenously with solutions that lack lecithin and choline start to have liver cell death," says Dr. Zeisel. "This can be reversed when you give them a lecithin or choline supplement."

One form of choline, choline, phosphatidylcholine (PC), seems to be particularly beneficial to the liver. In clinical studies, PC helped with alcoholic liver damage, cirrhosis, viral liver damage, and drug-induced liver damage. Animal research showed that PC supplementation was superior to any other treatment for alcohol-induced liver damage and cirrhosis.

PC is found in small amounts in most lecithin supplements. Greater concentrations are available in supplements labeled PC or Leci-PC.

Closely related to the way lecithin benefits the liver is the way it helps to prevent gallstones. The lecithin has a blending effect on bile salts and bile components. Without lecithin, the proteins in bile would separate out and form gallstones, says Dr. Zeisel.