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Types of Lipoproteins

Lipoproteins carry cholesterol through the bloodstream. Cholesterol produced by the liver is combined with protein in order to move the cholesterol throughout the body. There are four types of lipoproteins classified based on density: chylomicrons, VLDL, LDL and HDL. The density is based on the fat to protein ratio (lower density has a greater fat to protein content).

  1. Chylomicrons

    • Chylomicrons are the lowest density lipoproteins and are composed of as much as 90 percent fat, phospholipids, cholesterol and protein.

    VLDL

    • VLDL refers to very low density lipoproteins that are composed of a high ratio of fat, phospholipids, cholesterol and protein. The percentage of fat in VLDL makes this type of lipoprotein a negative component in the blood.

    LDL

    • LDL refers to low-density lipoproteins and is considered the "bad" lipoprotein and is unhealthy. LDL has a fraction of the fat of VLDL and double the protein. However, this lipoprotein is very high in cholesterol.

    HDL

    • HDl refers to high density lipoprotein and this is the healthiest lipoprotein. It is composed of a high percentage of protein, some cholesterol, phospholipids and a small portion of fat.

    Good Versus Bad

    • HDL is considered the good lipoprotein because it collects cholesterol and carries it to the liver, deposits it there, and then the liver excretes it from the body. This is called reverse cholesterol transport, and the cholesterol collected by HDL comes from the arterial wall and from tissue throughout the body. The other lipoproteins operate in the opposite manner, collecting cholesterol and depositing it into cells.

      HDL is an antioxidant that battles free radicals and is also an anti-inflammatory. HDL reduces the risk of stroke and heart attack by decreasing the blood's clotting ability. LDL is considered the worst lipoprotein because it circulates throughout the body, collecting cholesterol and depositing it into cells. VLDL is produced initially, and as it circulates, the fat content decreases and the cholesterol increases, changing VLDL to LDL. The greater amount of LDL in the blood, the greater the risk of heart disease.

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