Cholesterol Health Dictionary

Cholesterol is a porridge-like substance found in animal fats: cream, whole milk, cheese, butter, meat, eggs, bacon, etc. There are two kinds of cholesterol in human blood serum, one of which is beneficial; the other, harmful if in excess. The beneficial, known as high density lipoprotein (HDL) is believed to keep down concentration of the harmful variety – low density lipoprotein (LDL). The desirable blood cholesterol level should be less than 5.2 mmol per litre. (Government: “Health of the Nation”)

Cholesterol is necessary for maintenance of brain and glandular system, the production of bile salts and certain hormones.

Excesses plug arteries with a gluey consistency. Fats may start furring up arteries from childhood, yet it may take many years for symptoms to develop. The more meat and dairy products eaten the more cholesterol is produced. 90 per cent cases of gall stones are composed of cholesterol. A link between coronary heart disease and high cholesterol levels is strong and consistent. Anger and hostility raise cholesterol level.

The first indication of narrowing of the arteries may be an attack of angina, severe chest pain occurring on exertion due to an inadequate supply of blood and oxygen to the heart muscle. No one should exceed a fat and cholesterol count of 40 per day. For those of moderate risk level, a count of below 30 is advised.

Dr Paul Durrington, consultant physician, Manchester Royal Infirmary and researcher in lipids, believes that ‘reducing the amount of saturated fats in the diet and reducing weight are the most effective ways of lowering cholesterol levels’.

Treatment: same as for HYPERLIPIDAEMIA.

Diet. See: DIET – CHOLESTEROL. 

A fat-like substance that is an important constituent of body cells and is also involved in the formation of hormones and bile salts. Cholesterol in the blood is made by the liver from foods, especially saturated fats, although a small amount is absorbed directly from cholesterol-rich foods such as eggs. High blood cholesterol levels increase the risk of atherosclerosis, and with it the risk of coronary artery disease or stroke. In general, cholesterol transported in the blood in the form of low-density lipoproteins (LDLs) or very low-density lipoproteins (VLDLs) is a risk factor for these conditions, while cholesterol in the form of high-density lipoproteins (HDLs) seems to protect against arterial disease. Blood cholesterol levels are influenced by diet, heredity, and metabolic diseases such as diabetes mellitus, and can be measured by blood tests. Levels below 5.2 mmol/L are acceptable; higher levels may require further tests. Dietary changes can lower cholesterol slightly; drugs such as simvastatin achieve a greater reduction.

A LIPID that is an important constituent of body cells and so widely distributed throughout the body. It is especially abundant in the brain, nervous tissue, adrenal glands and skin. It is also found in egg yolk and gall-stones (see GALLBLADDER, DISEASES OF). Cholesterol plays an important role in the body, being essential for the production of the sex hormones as well as for the repair of membranes. It is also the source from which BILE acids are manufactured. The total amount in the body of a man weighing 70 kilograms (10 stones) is around 140 grams, and the amount present in the blood is 3·6–7·8 mmol per litre or 150–250 milligrams per 100 millilitres.

A high blood-cholesterol level – that is, one over 6 mmol per litre or 238 mg per 100 ml – is undesirable as there appears to be a correlation between a high blood cholesterol and ATHEROMA, the form of arterial degenerative disease associated with coronary thrombosis and high blood pressure. This is well exempli?ed in DIABETES MELLITUS and HYPOTHYROIDISM, two diseases in which there is a high blood cholesterol, sometimes going as high as 20 mmol per litre; patients with these diseases are known to be particularly prone to arterial disease. There is also a familial disease known as hypercholesterolaemia, in which members of affected families have a blood cholesterol of around 18 mmol per litre or more, and are particularly liable to premature degenerative disease of the arteries. Many experts believe that there is no ‘safe level’ and that everybody should attempt to keep their cholesterol level as low as possible.

Cholesterol exists in three forms in the blood: high-density lipoproteins (HDLs) which are believed to protect against arterial disease, and a low-density version (LDLs) and very low-density type (VLDLs), these latter two being risk factors.

The rising incidence of arterial disease in western countries in recent years has drawn attention to this relationship between high levels of cholesterol in the blood and arterial disease. The available evidence indicates that there is a relationship between blood-cholesterol levels and the amount of fat consumed; however, the blood-cholesterol level bears little relationship to the amount of cholesterol consumed, most of the cholesterol in the body being produced by the body itself.

On the other hand, diets high in saturated fatty acids – chie?y animal fats such as red meat, butter and dripping – tend to raise the blood-cholesterol level; while foods high in unsaturated fatty acids – chie?y vegetable products such as olive and sun?ower oils, and oily ?sh such as mackerel and herring – tend to lower it. There is a tendency in western society to eat too much animal fat, and current health recommendations are for everyone to decrease saturated-fat intake, increase unsaturated-fat intake, increase daily exercise, and avoid obesity. This advice is particulary important for people with high blood-cholesterol levels, with diabetes mellitus, or with a history of coronary thrombosis (see HEART, DISEASES OF). As well as a low-cholesterol diet, people with high cholesterol values or arterial disease may be given cholesterol-reducing drugs such as STATINS, but this treatment requires full clinical assessment and ongoing medical monitoring. Recent research involving the world’s largest trial into the effects of treatment to lower concentrations of cholesterol in the blood showed that routine use of drugs such as statins reduced the incidence of heart attacks and strokes by one-third, even in people with normal levels of cholesterol. The research also showed that statins bene?ted women and the over-70s.

A fatty substance produced predominantly by the liver, and necessary for building cell membranes, insulating the CNS, covering fats for blood transport, forming bile acids, oiling the skin and making steroid hormones. Blood cholesterols are not derived from food (digestion breaks them down) but are intentionally synthesized by the liver, in response to seeming need. Elevated cholesterols are the result of certain types of stress or metabolic imbalances, and the liver makes more than the tissues need. Although not a direct cause, high consumption of fats and proteins will convince the liver to kick into a fat/protein or anabolic stance...THEN it may oversecrete cholesterols, perhaps thinking you are putting food away for the winter.

n. a fatlike material (a *sterol) present in the blood and most tissues, especially nervous tissue. Cholesterol and its esters are important constituents of cell membranes and are precursors of many steroid hormones and bile salts. Western dietary intake is approximately 500–1000 mg/day. Cholesterol is synthesized in the body from acetate, mainly in the liver, and blood concentration is normally 140–300 mg/100 ml (3.6–7.8 mmol/l). An elevated concentration of cholesterol in the blood (see hypercholesterolaemia) is often associated with *atheroma, of which cholesterol is a major component. Hypercholesterolaemia and the resulting atheroma have been linked with a high dietary intake of saturated fats and cholesterol. However, current thinking suggests that the damage to blood vessels is caused by high levels (over 4.4 mmol/l) of *low-density lipoprotein (LDL), one of the forms in which cholesterol and other lipids are transported in the bloodstream. See also hyperlipidaemia; lipoprotein.

a steroid alcohol found in nervous tissue, red blood cells, animal fat and bile. Excess can lead to gallstones.