Fatty Acids
Part 3

How fat consumption can influence the course of HD

The relation between fat and nerve cells

Nutrition is an integral component of our daily life routine and it has the potential to modulate brain health and function. Although it may at first seem strange, fat is essential for brain development and maintenance. In fact, about two-thirds of the brain is composed of fat, which may come as a surprising statistic. Where is all that fat? It is found in two places associated with nerve cells themselves. First, the protective covering of nerve cells called myelin is 70% fat. More importantly, the membranes of nerve cells are made of a thin double-layer of fatty acid molecules. After the body breaks down fat from the diet into fatty acids, the brain then uses these fatty acids by incorporating them into its cell membranes. Nerve cell membranes are extremely important because their composition determines what is able to pass into and out of the cell. Oxygen, glucose, and the nutrients that the cell needs to survive all must pass through the membrane and into the cell´s interior. When saturated fatty acids are incorporated into normally very fluid cell membranes, they pack very tightly because saturated fatty acid chains have no gaps. Thus, essential nutrients are unable to get into the cell, making the cell less healthy and more prone to injury. In contrast, unsaturated fats can be beneficial to nerve cells because they prevent the tight packing of fatty acids in the membrane. Unsaturated fatty acids have gaps in their chains and these gaps allow for a certain amount of "fluidity."

Membrane fluidity is absolutely essential for the optimal function of most cells in the body, but it is especially important for nerve cells. In addition to letting in essential nutrients and keeping out harmful substances, nerve cell membranes also contain proteins that act as receptors for some neurotransmitters. Neurotransmitters are the chemical messengers that nerve cells use to communicate with each other. (For more information on neurotransmitters and their role in HD, click here). In order for the receptors to be able to recognize neurotransmitters and send along the messages that they contain, the nerve cell membrane must be fluid. If the nerve cell membrane is too rigid, the receptors on the membrane become less capable of recognizing neurotransmitters and passing along messages to the nerve cell. Often, the messages contained in neurotransmitters are critical to the survival of the nerve cell. Thus, membrane composition is extremely important because it influences nerve cells´ ability to communicate with each other and, ultimately, survive.

Studies reveal that optimal membrane composition is obtained when one consumes equal amounts of saturated and unsaturated fat. However, nutritional studies show that the average North American eats three times as much saturated fat as unsaturated fat! The addition of trans fat to the diet has made the situation even worse. Let us consider each fat in the context of our cells. Although too much saturated fat is bad, a certain amount is necessary for the optimal functioning of the membrane. On the other hand, the cell membrane has absolutely no use for trans fat. When trans fat gets incorporated into nerve cell membranes, the membranes become less capable of performing many essential functions, making the nerve cells more prone to a variety of insults.

Last Modified: 04/12/2007

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