Why the Human Body Needs Cholesterol

Cholesterol gets a bad rap these days. After all, doesn’t it harden up your arteries and cause heart disease?

Actually, there’s a little more to it than that. Cholesterol is necessary for human health. Here’s why.

Cholesterol and the Cell Membrane

The membrane of each cell in the human body is made up of two layers of lipids. One of the most important lipids that make up cell membranes is cholesterol. In some cells, cholesterol may even make up as much as 50% of the membrane!

Why does the cell membrane require so much cholesterol versus any other lipid? Because cholesterol is relatively rigid compared to many lipids. Cholesterol is the perfect ingredient for keeping cell membranes strong and proof against ion infiltration, while still being flexible enough to allow for a full range of body motions.

Because of its role in the cell membrane, cholesterol is an important part of how the body recovers from inflammation. Any time any part of the body is suffering from inflammation, cholesterol is quickly transported to the source of the problem to begin the process of building new healthy cells. (Ironically, it is the much-maligned LDL cholesterol that is sent to the scene to carry out the repairs.)

Cholesterol and Hormone Production

Cholesterol is an important precursor for the manufacture of several key hormones. The list of hormones that require cholesterol for synthesis includes:

  • Progesterone.
  • Estrogen.
  • Testosterone.
  • Cortisol (produced by the adrenal glands; used to regulate blood sugar and ward off infection).
  • Cortisone (produced by the adrenal glands; used to control the body’s fight/flight response).
  • Aldosterone (produced by the adrenal glands; used to regulate blood pressure, maintain proper sodium levels, and conserve water in the body).

Cholesterol and Digestion

Cholesterol is also used by the body to make bile. Bile is produced in the liver and aids in digesting food, particularly large fat globules. Ironically, without cholesterol to produce bile, the body would be unable to process fats, and the fats would accumulate in the bloodstream, block the arteries, and cause heart disease.

Also of importance, bile is needed to help the intestines absorb fat-soluble vitamins from food. The fat-soluble vitamins are vitamins A, D, E, and K.

Cholesterol and Vitamin D Production

You’ve undoubtedly heard that your body can make its own vitamin D provided enough sunlight. Cholesterol is the secret ingredient in this process. When the sun hits your skin, it starts a chemical reaction that involves the conversion of cholesterol to vitamin D. This vitamin D then goes on to play a role in many body processes, ranging from mineral absorption to metabolism to immune response.

Cholesterol and the Immune System

By now, you may have noticed that cholesterol is important to good immune system function through its roles in hormone manufacture and vitamin D production. But there’s more! LDL cholesterol plays an additional role in the body’s defenses by attaching itself to bacterial toxins and neutralizing them.

Cholesterol and Nervous System Function

Did you know that the brain contains about 25% of the cholesterol volume of the entire human body? Cholesterol is key to the formation of brain synapses and neurotransmitters, both required for the proper firing of neurons. Proper neuron function is in turn necessary to the processes of learning and thinking. Low cholesterol has been associated with impaired mood, memory loss, and Alzheimer’s disease.

Cholesterol is also an important part of the myelin sheath that insulates nerve cells.

Can Cholesterol Levels Drop Too Low?

All of this begs the question—is it possible to have cholesterol levels that are too low? While this scenario is not terribly common, it can happen.

First off, it is important to note that the human body typically manufactures most of its cholesterol. The average American male synthesizes about 1,000 mg of cholesterol daily, while he eats only an additional 307 mg daily. Biosynthesis of cholesterol is very important to keeping the body running, as most of the cholesterol found in food is relatively poorly absorbed. The intestines will only allow more dietary cholesterol absorption if the body is not producing enough cholesterol to meet its many requirements.

Therefore, because cholesterol manufactured by the body plays a more important role than cholesterol consumed in the diet, abnormally low cholesterol levels are typically caused by something that impairs the body’s ability to manufacture and use cholesterol, particularly statin use, genetic defects, and endocrine disorders such as hyperthyroidism.

The consequences of excessively low cholesterol are not well understood at present due to a dearth of research, but they may include cancer and cerebral hemorrhage, as well as premature births in pregnant women. In most cases, however, the cause of the low cholesterol levels is probably more dangerous than the low levels themselves.

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