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Cholesterol

What is cholesterol?

Cholesterols, also known as cholesterol, are hydroaromatic hydrocarbons. Cholesterol is produced by the human organism itself. However, cholesterol is also supplied from the outside through food. It should be noted that cholesterol is only present in animal food but not in plant food. In a healthy adult, around 34% of cholesterol is taken in with food and 66% is produced by the body itself. In humans,cholesterol serves to build up steroid hormones such as oestrogens, gestagens and androgens. It is also used to produce bile acid in the liver and to build new tissue. In the blood, cholesterol is surrounded by a lipoprotein envelope. This lipoprotein envelope ensures, among other things, that the poorly water-soluble cholesterol can be better transported in the blood. Lipoproteins are classified according to their density. Of importance are the low density lipoproteins (low density lipoproteins), LDL for short, and the high density lipoproteins (high density lipoproteins), HDL for short.

The harmful LDL

Too much cholesterol usually also means too much harmful LDL cholesterol. LDL cholesterol is transported into the cells in the body with the help of special receptors. If there is too much LDL in the blood or too few receptors are present, arteriosclerotic deposits can form in the vessel walls. These are caused by excess LDL cholesterol being absorbed from the blood by the body's own scavenger cells (macrophages). The macrophages migrate into the vessel walls, so that over time a series of complex processes result in vascular constrictions in the form of plaques that endanger the blood supply. If these plaques become unstable and burst, the affected coronary artery can become completely blocked. This happens because thrombocytes, i.e. blood platelets, are deposited very quickly on the destroyed plaque area, forming a thrombus which then completely blocks the vessel. The result is a heart attack

The beneficial HDL

HDL cholesterols, on the other hand, are "useful" cholesterols. They have the special property of absorbing cholesterol already deposited in the vessel wall (LDL) and transporting it to the liver. There it is converted into bile acids and can be excreted into the intestine with the bile. HDL cholesterol therefore protects against arteriosclerotic deposits on the blood vessels. The following therefore applies:

The more HDL - the better.

Danger from cholesterol

A cholesterol level that is elevated over a longer period of time increases the risk of developing arteriosclerosis, also known as atherosclerosis. As already mentioned, this leads to deposits in the artery walls, in which cholesterol is also involved. This leads to vasoconstriction, which reduces blood flow. Such deposits are particularly common in the vessels that supply the heart with blood, i.e. the coronary arteries. This disease is called coronary heart disease, or CHD for short. The consequence of coronary vasoconstriction can be a vascular occlusion with a heart attack. An elevated cholesterol level is the most dangerous risk factor for CHD and heart attacks. For arteriosclerosis in the cerebral arteries, and therefore for strokes, increased blood pressure is the most important risk factor. The arteries in the legs are most at risk from smoking and diabetes mellitus. But for all organ areas, a combination of risk factors, including hereditary factors, significantly increases the risk. An elevated cholesterol level can be caused by a hereditary disorder of fat metabolism. However, cholesterol levels can also be elevated as a result of another disease, such as thyroid, kidney or liver disease. In many, if not most, cases, however, a poor diet is the reason for an elevated cholesterol level: Too much fat and cholesterol in the diet cause blood cholesterol levels to rise.

Standard values

The blood cholesterol test is part of the preventive check-up introduced with the health reform, which can be taken every two years from the age of 35 in the Federal Republic of Germany. However, even before the age of 35, regular testing is necessary for patients with a positive family history and/or arteriosclerosis. This is because the consequences of an elevated cholesterol level can become apparent from the age of 40, and in some people even earlier.

If the total cholesterol level is above 5.17 mmol/l (200 mg/dl) in addition to the following risk factors, treatment is absolutely necessary.

  • Positive family history
  • diabetes
  • high blood pressure
  • smoker
  • Taking the pill
  • being overweight

If these risk factors do not apply to a person, an LDL cholesterol value of up to 3.88 mmol/l (150 mg/dl) with a total value of less than 5.17 mmol/l (200 mg/dl) is not to be considered a cause for concern. However, men for whom one and women for whom two of the above risk factors apply should aim to reduce their LDL cholesterol level to below 3.49 mmol/l (135 mg/dl). In these cases, the cholesterol level should be checked annually.

In addition to the total cholesterol value, three other blood values must be determined in this case in order to be able to make a meaningful assessment of the health risk for a person:

  • The LDL cholesterol value, which provides information on how much cholesterol is present in these vessel-damaging envelopes in the blood. This value should not exceed 3.49 mmol/l (135 mg/dl) if one or more of the risk factors described are present; without the risk factors present, it should not exceed 4 mmol/l (155 mg/dl).
  • Secondly, the concentration of protective HDL should be determined. As mentioned, the higher the HDL cholesterol, the better. The HDL concentration in the serum should be at least 1.03 mmol/l (40 mg/dl) and the ratio of HDL to LDL should be between 1:3 and 1:4.
  • Furthermore, the triglyceride level should be below 1.8 mmol/l (160 mg/dl). If it is elevated, there may be another metabolic disorder that should be investigated and treated further. A very pronounced increase in triglycerides in the blood can also lead to an increase in the cholesterol concentration.

Low-cholesterol diet

The basis for treating high cholesterol levels that are not hereditary is a low-cholesterol diet. In the case of hereditary hypercholesterolemia, however, the use of medication is usually irreplaceable.

Fat consumption, general

The type of fats consumed with food has a significant effect on cholesterol levels. In addition to cholesterol, fats also consist of fatty acids. A distinction is made here between saturated, monounsaturated and polyunsaturated fatty acids. More monounsaturated and polyunsaturated fatty acids, and therefore fewer saturated fatty acids in the diet, lead to an increase in the uptake sites for LDL in the liver. As a result, the liver absorbs more of the harmful LDL cholesterol from the blood and the LDL cholesterol concentration in the blood falls. Animal fats contain a high proportion of cholesterol and saturated fatty acids. Vegetable fats, on the other hand, are rich in polyunsaturated fatty acids. Monounsaturated fatty acids are found in both animal and vegetable foods. It is considered acceptable to consume one third saturated fatty acids, one third monounsaturated fatty acids and one third polyunsaturated fatty acids. Ideally, almost half of the total fat content should be consumed as monounsaturated fatty acids and only ¼ each as saturated and polyunsaturated fatty acids. Furthermore, a maximum of 300 mg of cholesterol should be consumed daily with food. It should be noted that the proportion of fat in the daily diet has risen from around 20% in 1945 to 40% today. Today, the upper limit should be around 30%.

The following examples clearly show how much fat can be hidden in animal foods. The same quantities of similar foods provide very different amounts of fat:

Cholesterol-lowering measures

Weight reduction

Being overweight is a risk factor for a number of diseases. For example, for a number of types of cancer, arteriosclerosis, back and joint problems, to name but a few. By reducing excess weight, the concentration of protective HDL cholesterol in the blood can be increased and that of LDL reduced.

Exercise

Regular physical activity is very important, and regular exercise increases HDL cholesterol. The most beneficial sports are those that train endurance rather than those that provide short-term high performance. The following are therefore good: jogging, cycling, swimming, rowing or paddling or long walks.

Medication

If you have a congenital disorder of fat metabolism or if your cholesterol level has not decreased accordingly after a few months despite a consistent change in diet, cholesterol-lowering medication can help. However, the use of cholesterol-lowering medication is no substitute for a change in diet. Despite taking medication, a fat-modified diet is the most important measure for lowering cholesterol levels.