Cholesterol Health Article

Cholesterol

A waxy substance in the chemical family of alcohols synthesized in the liver and used by the body to produce bile, hormones, and nerve tissue

Cholesterol is a critically important compound in the human body. It is synthesized in the liver and used in manufacture of bile, hormones, and nerve tissue. High levels of cholesterol have been linked to heart disease.

The liver can manufacture about 600 mg of cholesterol a day, an adequate amount to meet the body's need. But cholesterol is also a part of the human diet, and it is found in many foods. A single egg yolk, for example, contains about 250 mg of cholesterol. Organ meats—like liver and kidneys—are particularly rich in the compound. A 3 oz (85 g) serving of beef liver, for example, contains about 372 mg of cholesterol and a similar-size serving of calves' brain contains about 2,700 mg of cholesterol. Because diets differ from culture to culture, the amount of cholesterol an individual consumes differs widely around the world. The average European diet includes about 500 mg of cholesterol a day, but the average Japanese diet contains only about 130 mg of cholesterol a day. The latter reflects a diet rich in fish rather than meat.

Cholesterol occurs in almost all living organisms with the primary exception of microorganisms. Of the cholesterol found in the human body, about 93% occurs in cells and the remaining 7% in the circulatory system. The brain and spinal cord are particularly rich in the compound. About 10% of the former's dry weight is due to cholesterol. An important commercial source of cholesterol is spinal fluid taken from cattle. Cholesterol is also found in myelin, the material that surrounds nerve strands. Gallstones are nearly pure cholesterol.

How one's body processes cholesterol is affected by both hereditary factors and diet. For most people, when the dietary intake of cholesterol greatly exceeds the body's needs, excess cholesterol will tend to precipitate out of blood and be deposited on arterial linings. The presence of such plaques (clumps) of cholesterol can lead to circulatory disorders such as heart disease. The concentration of cholesterol in human blood also varies rather widely, from a low of less than 200 mg/dL (milligrams per deciliter) to a high of more than 300 mg/dL.

Children of any age can be tested to determine the levels of cholesterol in their blood. In fact, many pediatricians believe testing should take place routinely at about ages 2 and 16. Because many children carry the genetic tendency toward high cholesterol levels and heart disease, such screening can pinpoint children early who could benefit from dietary changes. The American Academy of Pediatrics has recommended that children older than two follow the same nutritional guidelines as adults, eating no more than 30% of their daily calories from fat and only a small percentage of that from saturated fat. Before the age of two, a higher percentage of calories from fat is required to sustain the rapid growth characteristic of this stage of development

Researchers have attempted to assess which family factors are most likely to predict elevated cholesterol levels in children. Factors that seem likely to predict high cholesterol levels in children are family history of cardiovascular disease and parental cholesterol level. The

above table illustrates the percentage of children who would be screened for elevated cholesterol if parental cholesterol level is used as a factor in making the decision when to screen. These percentages represent the results of the Lipid Research Clinics Prevalence Study, reported in March 1992. In general, most pediatricians recommend that all children and adolescents eat a diet low in saturated fatty acid, low in total fat, and low in cholesterol.