Cholesterol

Cholesterol is a fatty substance (a lipid) that is an important part of the outer lining (membrane) of cells in the body of animals. Cholesterol is also found in the blood circulation of humans. The Cholesterol in a person's blood originates from two major sources; dietary intake and liver production. Dietary Cholesterol comes mainly from meat, poultry, fish, and dairy products. Organ meats, such as liver, are especially high in Cholesterol content, while foods of plant origin contain no cholesterol. After a meal, Cholesterol is absorbed by the intestines into the blood circulation and is then packaged inside a protein coat. This cholesterol-protein coat complex is called a chylomicron.
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The liver is capable of removing Cholesterol from the blood circulation as well as manufacturing Cholesterol and secreting Cholesterol into the blood circulation. After a meal, the liver removes chylomicrons from the blood circulation. In between meals, the liver manufactures and secretes Cholesterol back into the blood circulation.
We all have quite a lot of Cholesterol in our blood, and it is there for the excellent reason that it is an essential chemical for the efficient running of the human body. Only a small amount of this Cholesterol comes directly from the food we eat: most of it is made by our own body. Nevertheless, it is not a good thing to have too much. Unfortunately, some individuals have very high Cholesterol levels, and the cause is hereditary; about 25 people in 10,000 carry this trait. This is a worrying condition which requires constant monitoring and medical attention to correct it. For such people the battle against Cholesterol is never-ending because they are prone to heart disease. The rest of us are lucky by comparison, but that is little comfort to many people who now fear that they too are at risk unless they can reduce the amount of Cholesterol in their blood. If you find your blood Cholesterol level is too high you can generally reduce it by following the advice of a trained dietitian, which generally means eating less fat and more fibre, and especially soluble fibre.
Cholesterol is not a life-threatening toxin, but a medium-sized molecule that is really a building block for important parts of the body. In particular it is an essential component of cell membranes. Cholesterol also stabilizes a cell against temperature changes. It is a major part of the membranes of the nervous system, the brain, the spinal cord and the peripheral nerves. In particular it is incorporated into the myelin sheath that insulates the nerves from the surrounding tissue. Cholesterol is also the forerunner of important hormones such as the female sex hormone, oestradiol, and the male sex hormone, testosterone, and of vitamin D, which we need in order to utilize calcium and form bone. Nearly all body tissues are capable of making cholesterol, but the liver and intestines make the most. We require Cholesterol to produce the bile we need to digest the fats in our food, and the name itself comes from the Greek words for 'bile solids'.
Essential though Cholesterol is, there can be too much of it, and too much causes a build-up of deposits in the arteries, constricts them, and may even block them, with dire consequences.' The causes which are now seen as contributing to higher-than-normal Cholesterol levels are: hereditary factors, which are the most important; then high blood pressure; followed by stress, smoking, obesity and dietary cholesterol.