Cholesterol

Cholesterol is a critically important compound in the human body. It is synthesized in the liver and then used in the manufacture of bile, hormones, and nerve tissue.

But cholesterol is also a part of the human diet. A single egg yolk for example, contains about 250 mg of cholesterol. Organ meats 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, about 2,700 mg of the compound. 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, only about 130 mg a day. The latter fact reflects a diet in which fish rather than meat tends to predominate.

The human body contains a feedback mechanism that keeps the serum concentration of cholesterol approximately constant. The liver itself manufactures about 600 mg of cholesterol a day, but that output changes depending on the intake of cholesterol in the daily diet. As a person consumes more cholesterol, the liver reduces it production of the compound. If one's intake of cholesterol greatly exceeds the body's needs, excess cholesterol may then precipitate out of blood and be deposited on arterial linings.