The abbreviation HDL stands for High Density Lipoprotein, which translates as “high density lipoprotein”. Lipoproteins are substances consisting of lipids (fats) and proteins. Since these form a ball in the blood, they can transport various substances.
Inside the sphere, the hydrophobic (i.e. water-insoluble) components of HDL point to the inside, while the hydrophilic (water-soluble) components form the envelope. In this way, lipoproteins can transport mainly water-insoluble substances inside the blood. As an antagonist of LDL (low density lipoprotein), HDL is the so-called “good” cholesterol, which protects the body from many cardiovascular diseases.
HDL has mainly positive effects on the body’s metabolism, therefore there is no fixed upper limit for the HDL value. Instead, a lower limit has been found below which there is an increased risk of heart attacks, atherosclerosis and other vascular diseases. This lower limit is generally 40 mg/dl.
However, slight differences in the risk profile for men and women are found, which is why the HDL level should not fall below 35 mg/dl in men. For women, it should be above 45 mg/dl. It is also known that a HDL level above 65 mg/dl has a particularly positive and protective effect on the cardiovascular system. Furthermore, the general rule of thumb is that an increase in HDL levels of 1 mg/dl reduces the risk of suffering a heart attack by about 1%.
What is HDL needed for?
The lipoprotein HDL is well suited to transport non-water-soluble (hydrophobic) substances in the blood. HDL forms small transport spheres, which are usually filled with fats or fat-soluble (lipophilic) substances. HDL is the “good” cholesterol.
It is responsible for transporting harmful cholesterol from the body cells back to the liver. As the antagonist of LDL, HDL protects the human body from the harmful effects of cholesterol. For example, cholesterol is deposited in the blood vessels, where it triggers local inflammatory reactions and leads to the accumulation of plaques.
This leads to calcification of the vessels (see: arteriosclerosis). This can particularly affect the vessels that supply the heart with nutrients (coronary arteries). Therefore, increased cholesterol increases the risk of suffering a heart attack.
HDL now ensures that as much of this harmful cholesterol as possible is transported from the blood vessels and other cells back to the liver, where it is broken down and excreted via the bile. Thus HDL has a protective effect on the heart and the vessels. Since HDL is called the “good” cholesterol and transports cholesterol from all body cells back to the liver, a high HDL value is considered positive.
The higher the HDL level, the better the vessels are protected from dangerous fat deposits. These fat deposits consist of cholesterol. They trigger inflammatory reactions on the vessel walls.
There, further cells are subsequently washed up, which also attach themselves to the vessel wall. As a result, the vessel becomes narrower and the blood flow behind the constriction is reduced. The deposits in the area of the coronary vessels are particularly dangerous.
These supply the heart muscles with oxygen and other nutrients. If the vessels are narrowed, the heart is not sufficiently supplied. This can lead to a heart attack.
These negative effects are mainly caused by the counterpart of HDL, LDL (low density lipoprotein). Simply increasing the HDL level protects the body from these negative effects. However, the HDL value should always be considered in conjunction with the LDL value. Only a simultaneously low LDL value promises a low overall risk of cardiovascular disease.