Sources of Cholesterol

CHAPTER 7

  

Sources of Cholesterol

PART 1

Cholesterol and Digestion

You need cholesterol in order to digest food. One of the other major uses of cholesterol is the production of bile acids (also known as bile salts) in the liver. Bile contains a number of ingredients, including water, cholesterol, and bile acids. Bile is necessary for the absorption of fats from fecal matter passing through the intestine. READ MORE

Bile secreted from the liver is stored in the gallbladder between meals. When you eat, bile is discharged from the gallbladder into the intestine. However, bile acids don’t simply pass out of your body with the feces. About 95% are reabsorbed from the lower intestine and recycled back to the liver.

Some of the bile acids are lost in this process, however, and to replace them (and meet other needs) the liver synthesizes about 1,500-2,000 mg of new cholesterol each day from the products of fat metabolism. LESS
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PART 2

LDL- and HDL-Cholesterol

What Are Pattern A and Pattern B?
Cholesterol, carried by lipoproteins, is constantly transported in the blood between the liver and all the tissues of your body.

HDL-Cholesterol
High-density lipoprotein (HDL) cholesterol helps clear excess cholesterol from your body by transporting it to your liver for excretion. That’s why HDL-cholesterol is often referred to as the “good” cholesterol. READ MORE

LDL-Cholesterol
About two thirds of your cholesterol is low-density lipoprotein (LDL) cholesterol, often referred to as the “bad” cholesterol. As LDL-cholesterol travels through your system, cells in need of cholesterol trap and ingest the LDLs. If the cells don’t need the LDL-cholesterol, it remains in the bloodstream.

So is LDL cholesterol “bad”? The answer is both yes and no, depending on the size of the LDL particle. LDL particles come in a range of sizes.

  • Pattern A particles are larger and less dense LDL particles.

  • Pattern B particles are smaller and more dense LDL particles.

Many experts feel that Pattern A particles are harmless. This means your LDL level may be high, but if the LDL particles are all Pattern A, you may be nevertheless be healthy.

Pattern B particles, however, are small enough to penetrate through the endothelium—the smooth, innermost layer of an artery—and into the intima, the layer of the vessel between the endothelium and the media, the inner layer of smooth muscle tissue. LESS
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PART 3

OxLDL: The Black Sheep

Sometimes small LDLs spend enough time in your bloodstream to lose the antioxidants they’re packaged with by the liver and become oxidized. These small, oxidized LDL particles are called oxidized LDL (oxLDL). Oxidized particles can cause major damage to the cells and tissues they come into contact with. READ MORE

It’s very possible that oxLDL plays a major role in atherosclerosis. Because of its small size, oxLDL can pass through injured areas of the endothelium and enter into the intima. Or, small, unoxidized LDL particles may enter into the intima and there become oxidized by the AGEs, ROS, and other inflammatory factors. When oxLDL enters the intima, it further damages the vessel wall by adding to inflammation and attracting more white blood cells, especially macrophages, to the lesion. LESS
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PART 4

Triglycerides

Triglycerides are fats that provide much of the energy your cells need to perform. Like cholesterol, triglycerides are manufactured by your body and also come from the food you eat, like butter and oils. When you consume more calories than you burn, the excess is converted into triglycerides, carried in your blood, and stored in fat cells throughout your body. READ MORE

Triglycerides are carried by your bloodstream by intermediate-density lipoprotein (IDL), very-low-density lipoprotein (VLDL), and chylomicrons (CM).

  • IDL is about 40% triglycerides. IDL circulates in your bloodstream and then returns to the liver, where it’s converted into LDL-cholesterol.

  • VLDL is about 50% triglycerides. VLDL is formed in the liver and then travels in your bloodstream, where it releases triglycerides to body cells. Having a high VLDL level can mean you’re at increased risk of atherosclerosis.

  • CM are formed in your intestine from dietary fat. They’re about 90% fat. As they enter the bloodstream, they gradually give up their triglycerides. These trigycerides may be stored in your body’s cells, used for energy, or returned to the liver. The liver uses what remains of the CM to build VLDL.

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