DOES IT WORK:Lecithin and Alzheimer's disease
LECITHIN IS a fatty substance found throughout our bodies and in some foods. It is made up primarily of phospholipids, compounds found in all living organisms. These are the major component of cell membranes which allow cells to remain separated from one another. Lecithin is therefore crucial to the normal functioning of all living organisms.
Our livers normally make sufficient lecithin on a daily basis. Commercially, lecithin can be extracted from egg yolks or soy beans. The name lecithin comes from the Greek word for egg yoke. It is widely used in foods as a natural emulsifier to prevent the separation of fatty components from water-soluble components.
However, there is a growing interest in using lecithin as a dietary supplement, which led one of our readers to ask about its value.
Evidence from studies
Lecithin is crucial for the health of membranes and also plays a role as an antioxidant. This has led to claims that it helps both to lower the risk of cardiovascular disease and to prevent dementia and Alzheimer’s disease.
The claims about cardiovascular disease relate to laboratory studies that show that lecithin has antioxidant properties, and thus can be generally beneficial for health. In addition, some studies showed that animals fed diets rich in lecithin had reduced blood cholesterol levels.
Very few studies have been conducted in humans, and the benefits have not been clear-cut.
A certain amount of cholesterol is needed for healthy cell membranes. Cholesterol is transported in the blood attached to different carriers, leading to the terms LDL-cholesterol, HDL-cholesterol and total cholesterol.
The risk of heart disease is increased with high levels of LDL-cholesterol and total cholesterol, and with low levels of HDL-cholesterol. Studies of lecithin in humans have found no impact on LDL-cholesterol and total cholesterol levels, and that it can lower HDL-cholesterol levels.
The evidence is therefore not clearly positive.
Claims have been made since the 1920s that lecithin is a good “brain food” and will prevent deterioration of mental capacity. More recently, this has been translated into claims that lecithin prevents Alzheimer’s disease, dementia and other memory problems.
During the 1980s and 1990s, several trials were conducted to evaluate these claims. The majority of them found no beneficial effects from lecithin, either in preventing these illnesses or in treating them.
Lecithin is a normal part of most diets and usually causes no problems. Some recommendations suggest taking 20-50 grams per day, which in some people can cause diarrhoea, nausea or abdominal pain. Lecithin is a fat, and such large doses will contain a significant number of calories.
Also, lecithin contains omega-6 fatty acids. As discussed in Healthplus last week, our bodies need a balanced intake of omega-6 and omega-3 fatty acids. Most Western diets tend to include substantially more omega-6 fatty acids already.
Some of the claims about lecithin and mental health can be traced to biochemical information. Since 2001, the US Food and Drug Administration (FDA) has permitted authorised lecithin products to carry labels stating, “A good source of choline”. This has led to connections being made between lecithin and cholinergic diseases, one of which is Alzheimer’s disease. However, this does not mean lecithin treats these diseases.
The main compound in egg lecithin (and to a lesser degree in soy lecithin) is called phosphatidylcholine. This releases choline in the body which is required to make the body’s own lecithin and several other substances, including acetylcholine.
Deficiencies in acetylcholine have been proposed as a possible cause of Alzheimer’s disease. This proposal has not received widespread support, primarily because drugs known to increase acetylcholine levels are not effective in treating Alzheimer’s disease. However, claims continue to be made that lecithin provides choline in the diet and thereby helps prevent, or treat, cholinergic diseases. Very little evidence supports these claims.
Lecithin plays a vital role in all our cells, with almost everyone making enough within their own bodies. Supplements are unlikely to benefit Alzheimer’s disease.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University. He authored Alternative Medicine: The Christian Handbook, Updated and Expanded Edition, Zondervan, 2007