The alphabet of a healthy heart: cholesterol

What is the difference between HDL and LDL cholesterol?

HDL, affectionately called the ‘good’ cholesterol, protects our arteries from arteriosclerosis. It absorbs excess cholesterol in our blood and transports it to our liver. Here, the transported cholesterol is modified into bile acid and then released from the body. The ‘evil’ cholesterol LDL, on the other hand, is one of the main causes of arteriosclerosis. The LDL transports cholesterol from the liver to peripheral tissues where it rests in the vascular system for several days. During this period, it can be oxidized by aggressive oxygen radicals. The oxLDL, which is created through this process, can then accumulate along the vascular walls and be digested by macrophages, the scavenger cells in our immune system. Macrophages normally ‘eat’ (phagocyting) pathogenic organisms, tumor cells and dead cell particles. If they take in large amounts of oxLDL, they can cause an infectious reaction within the vascular walls. This results in a reconstruction processes within the vascular walls, like the storage of fats, cholesterol, calcium, and further components. The resulting structural deformations in the vessels are stove-shaped and referred to as plaques. They can lead to a loss of elasticity within the vascular walls and narrowing vessels, which impedes blood flow.

During this process, plaques with a fatty core can develop. They  are not covered by the innermost vascular wall layer (endothelium). In the endothelium’s place, a thin connective tissue-like cap covers the plaque. When the cap tears, it produces physiological wound healing processes. The body tries to block this in the vascular system by accumulating thrombocytes and initiating an active coagulation. The generated blood clot, or thrombus, can block the artery completely. If this happens within the region that is responsible for supplying blood to the heart, a heart attack will most likely occur. The thrombus can also peel away from the vascular wall completely or in parts, and can be protracted throughout the blood. This causes blood clots in far away vessels, such as in the brain, which can lead to a stroke.

The numerical value of HDL and LDL is hardly significant. Relevant risk scores, such as the Scoring System of the European Society of Cardiology (ESC), don’t mention the LDL cholesterol as an independent risk factor. What matters is the ratio between HDL and LDL cholesterol. Someone with high amounts of HDL and low amounts of LDL in their system is less likely to suffer from cardiovascular diseases than a patient with the contrary circumstance.

How can cholesterol levels be influenced?

Only one third of the cholesterol in our body is determined from our nutrition, while the other two thirds are produced by our body. Only a very strong consumption of animal products, such as butter or eggs, can lead to an increased blood cholesterol. Despite the comparatively low impact of nutrition cholesterol, patients with a disrupted cholesterol metabolism should still aim to maintain a low cholesterol diet.

Arteriosclerosis occurs mostly with older patients. However, studies have shown that young adults can develop reversible vascular deformations as well. To prevent or delay arteriosclerosis, individual risk factors should be reduced. Risk factors include high blood pressure, increased blood fat levels, obesity and lack of physical exercise. A well-balanced and healthy lifestyle is also important for our blood cholesterol and vascular health. Products that are high in fiber, such as whole wheat bread, legumes, brown rice varieties, fruits, and vegetables are helpful for achieving good vascular health. Studies have shown that in small doses, even dark chocolate and red wine can lower LDL levels, protecting our cardiovascular system as well.

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