Cholesterol is a waxy solid found in all animals. It's an essential component of animal cells and is used to build the cell membranes. Cholesterol is also needed in the synthesis of bile acids, hormones and vitamins. An excess of cholesterol in the blood is associated with an increase in the risk of heart disease.
Properties
The molecular formula of cholesterol is C27H46O, meaning that a molecule of cholesterol contains 27 atoms of carbon, 46 atoms of hydrogen and 1 atom of oxygen. It's a white powder at room temperature and melts at a temperature of about 150 degrees Celsius (302 degrees F). Cholesterol is slightly more dense than water at 1.052 grams per cubic centimeter (g/cm^3) and is only slightly soluble in water.
Function
Cholesterol maintains the fluidity of the cell membranes at body temperature. It accomplishes this by making the cell membrane less permeable to hydrogen ions (H+) and sodium ions (Na+). Cholesterol is also believed to play a role in the synthesis of lipids in the plasma membrane. The myelin sheath of neurons is frequently rich in cholesterol, which makes the conduction of neural impulses more efficient.
Arteriosclerosis
Cholesterol can accumulate on the interior walls of the arteries, resulting in a condition known as arteriosclerosis. This condition is the constriction and even blockage of the arteries. High cholesterol levels can be hereditary and may also be caused by hypertension, obesity, smoking, stress and a high intake of fats.
Sources
Cholesterol may be synthesized by the body and it can also be obtained in the diet. A person weighing 150 lbs. will synthesize about 1,000mg of cholesterol per day and the daily intake of cholesterol is an additional 200 to 300mg per day. Foods that are high in cholesterol are primarily animal products that come from red meat and whole milk.
Diet
People wishing to reduce their cholesterol level should limit their intake of fats, especially saturated fates. Total fat intake should comprise no more than 35 percent of the total caloric intake. Saturated fats should make up less than 7 percent of the total number of calories consumed. The intake of dietary cholesterol should be no more than 200mg per day.
