What Is Cholesterol?

Cholesterol is a type of lipid found in the cells of all body tissues. It is not considered essential because our body makes it in the liver. It is a fatty substance, but unlike fat, it does not provide you with energy. You can’t taste it or smell it, but it is in the food you eat, and your body needs it to function properly.

Every cell in your body contains cholesterol. Cholesterol carried in your bloodstream is called blood serum cholesterol. It is transported by blood plasma throughout the body and is used to make cell membranes, bile acids that allow us to digest fats, hormones, and vitamin D. Like so many things, too much cholesterol can be dangerous.

When it is in your food it is called dietary cholesterol. Found mainly in animals, you find lots of it in shrimp, egg yolks, dairy products, and meat.


Because fat does not dissolve in water, it is transported through the bloodstream by water-soluble proteins called lipoproteins. They wrap the cholesterol and triglycerides like a package and deliver it throughout the body. From the liver, triglycerides and cholesterol are secreted into plasma, where they are joined with low-density lipoprotein (LDL).

Termed the “bad cholesterol,” LDL is thought to increase the risk of heart disease, heart attacks, and stroke. Healthy blood has fairly few large particles of LDL. If too many accumulate, problems occur. When LDL accumulates on the walls of the arteries it can harden them and cause blockage. This is called arterial plaque. If blockage occurs in a main heart artery, a heart attack is the result. If blockage occurs in a major brain artery, stroke can result.

High-density lipoproteins (HDL) circulate in the blood, picking up cholesterol and excess plaque and transporting it back to the liver, where it is excreted as bile. For optimal health, levels of LDL should be low, and levels of HDL should be high. Your cholesterol levels can be determined by a blood test. Healthy ratios of total cholesterol to HDL should be below 5:1, with an optimal ratio of 3.5:1.

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