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Importance of Cholesterol to the Myelin Sheath

Your nervous system contains a fatty substance, known as myelin, which provides insulation for your brain and spinal cord, and the nerves that course through your body. Fat comprises 60 percent of your gray matter, the nerve cells and processes, in your central nervous system, according to Maggie Greenwood-Robinson, author of the book "Good Fat vs. Bad Fat." Cholesterol, a waxy substance that your liver produces from fats you ingest, is a central component of myelin.

Background

Cholesterol comprises the cell membrane structure of every cell in your body. In your nervous system, cells called Schwann cells grow exceedingly large cell membranes, which wrap tightly around the long processes of nerves. Cell membranes of Schwann cells are unique in that they contain as much as 50 percent more cholesterol and up to 75 percent less protein than other types of cell membranes. This wrapping forms a thick insulating layer of cholesterol-based cell membrane known as myelin.

Development

Myelin keeps nerve electrical impulses flowing along the nerve process toward their intended recipient nerves and prevents electrical impulses from accidentally activating nearby nerves. During healthy brain development the levels of cholesterol in your brain and spinal cord rise tremendously. With age these levels naturally decline, implying that adequate cholesterol synthesis is important for production of sufficient myelin to ensure proper brain function through all phases of life.

Insulation and Fluidity

High-quality myelin relies on sufficient cholesterol. Cholesterol contributes to the insulating effects of myelin by preventing leakage of electrically charged substances from nerve cells. Without sufficient cholesterol, myelin production and quality suffer, resulting in neurological deficits, such as tremor and difficulty walking. Myelin may also contain a small percentage of saturated fatty acids, which decrease the fluidity of the myelin membrane compared to cholesterol, which provides considerable membrane fluidity, according to Patricia Armati, PhD., editor of the book "The Biology of Oligodendrocytes."

Demyelination

Neurologic disorders from damage to myelin, known as demyelination, can occur from a variety of causes. One of the most common demyelinating diseases is multiple sclerosis. This and other demyelinating diseases are often characterized by cycles of myelin damage followed by healing that lead to a pattern of relapsing and remitting nerve symptoms, according to Mark Freedman, editor of the book "Multiple Sclerosis and Demyelinating Diseases." Though the precise cause for multiple sclerosis is unknown, it is classified as an autoimmune disease, one in which the immune system attacks myelin as if it were a foreign substance. One theory for the cause of multiple sclerosis holds that deficiency of vitamin D, which is synthesized from cholesterol, leads to immune dysfunction that may increase the risk for this autoimmune disease, according to Dr. Ryan E. Bentley, author of the book "Sex, Lies and Cholesterol."

References (6)

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This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.