Cholesterol is a fat (lipid), belonging to the class of sterols, very important for the human body; the body, in fact, needs it in adequate quantities since it is the fundamental constituent of cell membranes and some hormones; Furthermore, cholesterol is important for the development and functioning of brain cells.
The presence of excessive amounts of cholesterol circulating in the blood, however, is harmful because it causes atherosclerosis (from the Greek athero = mush, sclerosis = hardening). This disease is characterized by the deposition of cholesterol, calcium, fibrin, lipids and cellular degradation products in the inner layer of large and medium-sized arteries with the formation of thickening called atherosclerotic plaques (atheromas). The arteries most affected are the coronary, carotid, renal, iliac and femoral arteries. Atherosclerotic plaques can rupture causing thrombi and / or emboli which can lead to heart attack, stroke, and peripheral vascular disease.
The laboratory test to measure the level of cholesterol in the blood (total cholesterol), unlike most clinical tests, is not used to ascertain (diagnose) or monitor cardiovascular disease but to estimate the risk of developing it or, if already present, to face complications.For this reason, the control of cholesterolemia, together with the measurement of blood pressure (arterial pressure), the habit of smoking, the presence of diabetes, can give indications on the probability (risk) of developing cardiovascular disease in the following years, is to say before it actually manifests itself In this way, by identifying the risk, it is possible to achieve effective prevention.
Cardiovascular diseases are multifactorial, i.e. multiple risk factors contribute to their development at the same time, some of which cannot be modified (age and sex), others that can be modified, including total cholesterol levels in the blood (total cholesterolemia).
Cholesterol is linked to:
- low density lipoprotein (LDL), consisting mainly of fat and a small amount of protein; this type of cholesterol is deposited in the wall of the arteries and can obstruct them, therefore it is often referred to as "atherogenic cholesterol" or "bad cholesterol"
- high density lipoprotein (HDL), composed mainly of proteins plus a small amount of fat; this type of cholesterol is not deposited in the arteries and is therefore often referred to as "good cholesterol"
For this reason it is good to measure both total cholesterol and LDL and HDL cholesterol levels.
Cholesterol is partly produced by the liver and partly introduced with food. By following a diet low in animal fats (saturated fats), cholesterol and sugars, adequate and regular physical activity and eliminating the habit of smoking, it is possible to reduce the amount of cholesterol in the blood (cholesterolemia) and, consequently, also the risk of developing cardiovascular disease. This has been amply demonstrated.The high consumption of animal products (red meats, fatty meats, sausages, lard and bacon, egg yolks, cheeses, butter and cream, foods that contain coconut or palm oil) and high-calorie foods, increases the level of total cholesterolemia (read the Hoax).
On the other hand, including polyunsaturated fats (of vegetable origin) in the diet decreases the levels of total cholesterol in the blood (read the Buffalo) and increases those of HDL cholesterol. Foods rich in polyunsaturated fats include: oily fish, avocado, nuts and seeds, sunflower and rapeseed oil Extra virgin olive oil is rich in monounsaturated fats, monounsaturated fats also have the peculiarity of lowering LDL cholesterol levels and increasing HDL cholesterol levels.
A healthy, varied and balanced diet is low in calories, rich in vegetables and fruit, cereals, legumes, fish and low in salt.
The cholesterol test is commonly prescribed by the doctor when you reach the age of 40. However, it can also be performed earlier if you think you are at risk of cardiovascular disease.
In addition to cholesterol, the other cardiovascular risk factors are:
- high blood pressure (arterial hypertension, i.e. blood pressure values equal to or greater than 140/90 mmHg)
- overweight, obesity
- first degree family members (parents, brothers / sisters, children) who have, or have had, cardiovascular disease (heart attack or stroke) before the age of 55 if they are male, or before the age of 65 if they are female
It is useful to measure blood cholesterol levels (total cholesterol) and its fractions (HDL and LDL cholesterol) at regular intervals if medications (statins, ezetimibe) have been prescribed.
L'familial hypercholesterolemia it is a rare condition that occurs when the amount of cholesterol in the blood is very high and does not decrease after following a healthy diet, the abolition of smoking and practiced regular physical activity for at least six consecutive months. The ascertainment (diagnosis) of familial hypercholesterolemia requires specific tests and evaluation by the doctor who, after examining the results of the analyzes, will decide whether to prescribe drugs to be taken continuously to counteract the risk of heart disease occurring at a young age. a hereditary disease, familial hypercholesterolemia may also be present in other family members.
In general, the amount of cholesterol in the blood is lowered during the acute phase of an illness, for example immediately after a heart attack or in a period of stress (due to surgery, an accident, etc.). To have a correct measurement of cholesterol it is therefore necessary to wait at least six weeks after any illness. A low cholesterol content is often found in cases of malnutrition, liver disease or cancer. It has long been debated among scholars whether a cholesterol level far below normal can be harmful. In particular, if it favors impairments of cognitive ability.
Some drugs increase cholesterol levels, for example corticosteroids given by mouth (orally), beta blockers, oral contraceptives, thiazide diuretics, oral retinoids, and phenytoin.
In women, cholesterol increases during pregnancy and it is therefore necessary to wait at least six weeks after giving birth to undergo laboratory analysis.
The examination of cholesterolemia
The laboratory analysis to check total cholesterol levels consists of a blood sample to be performed fasting for at least 12 hours; it is preferable to always carry it out in the same laboratory in order to minimize variations due to the method used to determine it. Taking medications before undergoing the blood draw does not alter the cholesterol measurement.
The results of the measurement of total cholesterol in the blood must be seen and interpreted by the doctor who, based on the general health conditions, and the level of other risk factors, will indicate whether it is sufficient to resort to a healthy diet and physical activity regular, or if you need to take medications to lower cholesterol (statins, ezetimibe).
There is no "normal" or "abnormal" value for total cholesterol, as each value is associated with a risk, which is higher the greater the contribution of the set of risk factors (absolute global cardiovascular risk) but it is considered desirable to have a value of less than 200 milligrams per deciliter (mg / dL). The risk of cardiovascular disease decreases by maintaining cholesterol levels at desirable levels over the course of life.
If a cardiovascular event has already occurred, cholesterol-lowering drugs should be taken regularly, even when the cholesterol level is not high, according to the instructions of the treating physician.
Heart Project (ISS)