Why do you say there is "good" and "bad" cholesterol?

"You have too much cholesterol": one day or the other, one in five adults will receive this medical sentence and should from this moment "pay attention to his cholesterol". While until then, this molecule had not manifested itself, here it comes from the shadows and threatens your health. With the key, an increased risk of myocardial infarction, stroke or arteritis of the lower limbs. Yet cholesterol is a valuable service throughout our lives. This molecule of the family of lipids (fat, if you prefer) is responsible for several vital functions. So why are we talking about "good" and "bad" cholesterol?

In reality, these qualifiers do not refer to cholesterol itself but to its mode of transport. Cholesterol is a particle of fat, it does not support water. To be transported in the body via the blood, composed mainly of water, it must therefore help "vehicles" which themselves do not fear the water. These are proteins that can exist in many forms, the two main ones being low density lipoproteins (called "LDL") and high density lipoproteins ("HDL"). When he is on board an HDL protein, cholesterol is called "good" cholesterol. But when it takes place in an LDL protein, everything switches. This is called "bad" cholesterol.

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Excess LDL Cholesterol Degrades Blood Vessels

Why this distinction? To understand it, you have to take a closer look at the route taken by these two carriers. LDL proteins carry cholesterol from the liver to other cells in the body. It is indeed in the liver that most of the cholesterol is manufactured. The rest is brought by our food. Once the cells have received it, they mainly use it to make their membranes, but it also serves as a raw material for the production of vitamin D and certain hormones such as testosterone or cortisone. In the brain, cholesterol helps to form connections between neurons. Cholesterol is also one of the ingredients of bile, a fluid that helps digest fats.

When the LDL carrier delivers cholesterol to the cells that need it, it may lose some on the way. The cholesterol will then cling to the artery wall and, over time, accumulate, harden, thicken and gradually deteriorate the blood vessels: it is atherosclerosis. Excess "bad" cholesterol also promotes clot formation. A silent phenomenon that can eventually lead to brutal cardiovascular events. A study published in 2015 showed that in industrialized countries, one in four deaths is linked to arteries damaged by atheromatous plaques.

The HDL proteins do the opposite: they recover excess cholesterol from the cells and return it to the liver so that the accumulated surplus is eliminated. These carriers also have the role of preventing the formation of clusters of cholesterol (the famous plaques of atherosclerosis) on the wall of the arteries. Hence the nickname "good" cholesterol.

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A diet low in fat

Only excess LDL cholesterol is dangerous for health. It can have different origins, the main one being a diet too rich in saturated fats (dairy products, meats, eggs). Some people may also have the misfortune of having an unfavorable genetic terrain. This is called familial hypercholesterolemia. At home, LDL cholesterol is less well eliminated. In addition, there are a number of diseases that promote the production of "bad" cholesterol, such as diabetes, diseases affecting the kidneys, the liver or the thyroid. Finally, drugs like those used against acne, cortisone and some oral contraceptives can increase cholesterol levels, but this trend is reversible.

It is quite possible to control your cholesterol levels, first by having a physical activity and by following a diet: to limit its consumption of fats of animal origin, to avoid nibbling, to privilege the vegetable fats and the lightened products. With these simple measures, the cholesterol level can decrease up to 15%, as indicated by the French Federation of Cardiology. If necessary, there are effective drugs.